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After seeing the underside of the tank, with all the press marks and the tank mounts, I think it's a genuine Honda CB1100R one.
You should put it on eBay and see what someone might pay for it, you may be surprized. You could put that cash towards a much better bike to rebuild or modify. I think this one is a very borderline example, taking into account of what it's going to cost to get it running half right.

Sand blasting ally is not a very good idea for many reasons, it rips the crap out of the aluminium for one. Don't sand blast bike parts, it's usually way too savage. If you sand blast your cylinder head, the chances are you will ruin it, like into a throw away item. Don't sand blast your carbs!

Repairing ally tanks is really a job for pros.

Danger, is my business.
 

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After seeing the underside of the tank, with all the press marks and the tank mounts, I think it's a genuine Honda CB1100R one.
You should put it on eBay and see what someone might pay for it, you may be surprized. You could put that cash towards a much better bike to rebuild or modify. I think this one is a very borderline example, taking into account of what it's going to cost to get it running half right.

Sand blasting ally is not a very good idea for many reasons, it rips the crap out of the aluminium for one. Don't sand blast bike parts, it's usually way too savage. If you sand blast your cylinder head, the chances are you will ruin it, like into a throw away item. Don't sand blast your carbs!

Repairing ally tanks is really a job for pros.

Danger, is my business.
My alloy TR2 tank had been blasted at some point in it's life. It made me want to cry. It has now been repaired, but I wouldn't trust it. Another thing with blasting, if the media is full of crap, you might have fun trying to tig weld the thing. That tank looks like it was blasted with something really aggressive, so how thin and brittle is it now. Also, wonder what the story is behind the hole in the bottom?
 

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My alloy TR2 tank had been blasted at some point in it's life. It made me want to cry. It has now been repaired, but I wouldn't trust it. Another thing with blasting, if the media is full of crap, you might have fun trying to tig weld the thing. That tank looks like it was blasted with something really aggressive, so how thin and brittle is it now. Also, wonder what the story is behind the hole in the bottom?
Yeah, like I've alluded to; blasting ally tanks with sand can heat the ally up in spots and distort it. If the blast media is sand or contaminated, it can cause problems contaminating paint and welds. Even polishing an ally tank with sand grit embedded in the surface can be a hassle.

There is no reason to blast ally tanks. Paint strippers are much better suited to the purpose.

I can only think of two pros who could work out if this tank can be recovered, ones dead, and the other one I haven't seen in decades.

Danger, is my business.
 

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Discussion Starter #84
Sandblasting tanks, wont do that again. Pity I had not yet joined the forum earlier. Oh well.... Witworth you need not worry about further sandblasting, will not be doing anything to the engine in this regard.

The cool thing about the weekend was that I did get some new second hand parts for the bike. Whilst chatting to the guys at the bike salvage yard, they said to me that I better look of this bike, as they are getting nicked for parts. Apparently, lots of 900c's locally, but not too many F's. In sourcing the a new vacuum cylinder (Top Cap), at the salvage yard, I was shown to a bin with over 200 top caps in, and after looking through about 30% of them, I can confirm not a single one had any lining inside. Also got a float bowl, as you will recall one had been mangled a bit.

New old bits.jpg
 

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Discussion Starter #85
Carbs Carbs and more Carbs. After 12 hours of cleaning, replacing jets etc etc. I am at this point. Carbs are looking much cleaner and almost together.

Carb cleaning half way.jpg Carbs Almost together.jpg

Somethings I noticed along the way was the secondary jet size was 98 which is smaller than the standard jetsize of 105 for this bike. Also because the main jet size is 68, secondary and primary jets seemed to have gotton mixed up by previous owner/s.

Cleaning not complete though as I have decided that before I put in more effort, I want to see if I could get the bike to run properly. Build plans for this weekend, is to finish carbs, flush engine.... hopefully get the bike running.
 

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Big improvement on the carbs. Another job worth thinking about is removing the sump and cleaning the oil strainer.
 

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Discussion Starter #87
Big improvement on the carbs. Another job worth thinking about is removing the sump and cleaning the oil strainer.
Thanks SteveO... tried them on the bike yesterday, only to notice that fuel was leaking from float bowls 1 and 2. Next time I am going to feed them fuel before putting them on the bike to check for leaks.... Man that airbox with rubber boots can get in the way. So first port of call will be to double check that the overflow tubes are not cracked, that the float valve seat is even cleaner than before and then try again.

Cheers
 

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Check the old oil for water contamination. It won't help the bearings or crank any when you fire it up.

Danger, is my business.
 

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Discussion Starter #89
Thanks for the advice Witworth. My idea of an engine flush, is to first flush with new oil, then to add an engine flush after that. Oil really is amazing stuff am always amazed at how it traps particles holds them in suspension, so that when you drain the all those particles come out. Oil that was drained, was incredibly dirty, so I am interested to see what it looks like after the flush again.

Sorted out the carbs last night.... Could have kicked myself a little here, my float bowl drain screws were not properly seated. As far as the tank goes, my brother did an amazing job of cutting the bottom off, even being able to not cut through the overlap metal around the base of the welds. Unfortunately, his involvement on the tank stops here for now as he severed some tendons in his right hand about a year ago so I am taking over the panel beating as it is just too painful for him to wield a mallet. Look forward to this little bit of work coming up.

The Tank.jpg
 

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If I had a CB1100R tank in two parts like that I'd be taking a GRP mould of it before tacking it back together.

By the way you don't polish ally tanks if you want to paint them. Just a gentle light treatment with a abrasive wheel of some kind. It helps spray putty or paint stick.

Be careful with the tank tap thread.

Any ally tank needs to be gently pressure tested with soapy water after welding or repairs. With a very low pressure. I've seen 30psi blow steel tanks up like mushrooms.

Danger, is my business.
 

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Discussion Starter #92 (Edited)
Why did you cut the tank in half?
Maybe its not that evident in other pics of the tank, put this tank has suffered some serious beatings in the past. It is clear that it came down on its left side at some stage, and is ever so slightly twisted. A poor repair job was originally made as it looks like the tank has been peppered with golf balls at close range on the left, as someone tried to push the dents outs. The main tank creases on the left side are much sharper than on the right. After consulting two engineering firms, two panel beaters and one precision welding firm the only hope for this tank was to open her up, so that we can get properly inside and improve the shape of the metal, with soft mallet, sandbag and some heat, or cut a hole from the opposite side and try and work it like that.

Cutting it just along the welds, was recommended by the welder, giving him more to weld against I assume. I took is word for it seeing it was a 30 year old father and son welding enterprise, with the best reputation in the area.
 

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Discussion Starter #93
If I had a CB1100R tank in two parts like that I'd be taking a GRP mould of it before tacking it back together.
[/I]
I am taking orders :) I could actually, my part of the world has some renowned GRP guys, partly because in this neck of the woods, we host the countries single biggest 3 day canoe marathon.
 

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Discussion Starter #94 (Edited)
and lastly..... The beast roared into live last night. After struggling for 10 mins on a cold evening, we got her running only to notice that she was running on the number 2 and 3 cylinders. Poked around a bit more and some wiring had come loose of the ignition coil ? for cylinder 1 and 4. After sorting that out. She started on the button, every time which was very encouraging. The afterburn/pop on deceleration is gone, but have a slight misfire on occasion when revving her up. Still need to synchronise the carbs on the bike though, which should get her running smoother. The slight misfire on acceleration is most probably due to the faulty air cut off valve's, mine where poked so will most likely just bypass these.

Will run her again today, drain the oil again and put some new oil in. Also noticed that I had the most peculiar sump plug. Its a spark plug with ceramic section cut off :rolleyes:
 

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Forget running the bike with those worn out and rusty cams. They will just wreck everything and probably end up trashing the head and cam journals. Like "throw away head style".

GRP is O.K. for tanks, but forget some guy who gets all excited about using Carbonfibre. It conducts electricity. I'd much prefer GRP.

Get some good shocks like Hagons, gas-charged Progressives or Icons. Forget the shiny reservoir junk shocks on eBay.

Danger, is my business.
 

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Wow it's odd that I had never noticed this thread before. Does anybody know of any more current updates? I'd love to see more progress, 'cause the end product - or at least the original, before it sat outside for 15-20yrs of bad weather, seems very similar to what I'M trying to do. With my "CB900K0 Bol Bomber" project. Similar enough that I could definitely understand if the project had hit some SNAGS along the way, maybe languishing in need of $$$ as much as answers, solutions, never mind time & effort spent working on it.

DAMN, it's funny how predictable the responses from our faithful leaders are. What a bunch of shit advice! (Wouldn't be at all surprised if the builder set up their build-thread ELSEWHERE, due to all of the snide negativity noobs are subjected to.)

Seriously though: A beautiful period-correct DOHC-4 Cafe, or "Special", "Street-Racer", what-have-you; expressing clear intent to RESTORE the thing - and yet the advice, straight off the bat from the PEANUT GALLERY, was to build it into the cookie-cutter "Super-'F" from the www.cb1100f.net 'F-orum. What I've come to call an "OREO" 'cause all of the cream's in the middle - with a whole front end from any random Gixxer and the Gixxy-er the better - typically monoshock conversion on the rear end, and heavy assed 17" mag wheels with fat tires aren't such a great answer either, especially given what they do to the whole profile of the bike especially on the rear! Incidentally, www.cb1100f.net is my main forum and my only 'F-orum by the way - I love that site. But there sure are a heck of a lot of hideous chachi crotch-rocket-wannabe bikes over there - built by folks who spend too much time looking at the modern shit - the ZRX1200 or GSX1300 type of shit. Funny how nobody even says "WHOAH - stop right now!" when people talk about doing all of THAT garbage to a classic bike, but ya'll jump down somebody's neck when they talk about a classy cafe racer conversion - and they're really only talking about a clubman bar and some rear-sets whey they say that, so why assume they're talking about the shit we've all seen on the bike-burn sites?

And always with the "Get some Keihin CR's" deal - Well I would've bought a set by now, if I'd ever heard from just ONE owner of a DOHC-4 running Keihin CR's, as to the FUEL ECONOMY after the switch. Too much emphasis on "bigger, faster" etc - When some of us are looking at these bikes for long-range touring & reliability, well - I'd really rather not piss a bunch of unburnt hydrocarbons into the atmosphere in the first place, but if it's gonna affect my fuel costs over a long-distance tour? Yep, that'd be a no.

Don't give people shit for taking the tank apart, either. I've got one of these same tanks on hand, and they're notoriously difficult to hammer back into shape, even very small dents. Well it's definitely odd that this specimen doesn't have the internal baffling, but mine does at any rate. That internal baffling might be there to resist fuel sloshing around, back before folks figured out the open-cell FOAM trick - It might well be in there to strengthen the panels I dunno - But what it definitely DOES is block any "Spoon" type tools, which you might want to insert through the filler spout, for backing up the dent while hammering away with a "Hardwood Slapper" type of panel beater tool. With a couple of purpose built spoons and slappers, one might well hammer out a lot of dents from a tank like this. OR, one might say needing to cut a hole in the bottom of the tank for dent repairs could be the perfect excuse for converting to EFI with a large ring mount underneath for running a fuel pump etc. Then again, the way these things fit to the frame where the heck would you PUT the damn pump? Wouldn't work well, not without having to use a siphon tube inside, so as to suck fuel from a low point along one side or the other.

These tanks aren't really all that expensive yanno. You'd pay more for an NOS tank or even well restored specimen off of the "lesser" DOHC-4 models - now that I've GOT one I feel less uneasy saying that more DOHC people should grab these things where and when they can. But at SOME point I'd like to make a mould or better yet SCAN the thing somehow. 'Cause IMHO the way to do it would be to "flow-form" the panels into a hard-wood "BUCK" mould.

Something else I find very interesting about the above tank, is that top panel seems to be all one piece? Mine's got a seam along the top center-line. I looked all up inside of the thing with a chopped-up webcam taped to a coat-hanger. I should dig up some pics sometime. One of the most wonderful things about an Aluminum tank is being able to rinse the thing out with hot soapy water - anybody restoring an old steel tank should take into account all of the crap they've gotta buy from the rust removers & sealants to the paint etc. Of course, it'll never add up to what I've spent on various grits of sand-paper, Aluminum polish, buffing pads etc. But if you're happy not polishing the damn thing, an Aluminum tank can be a good purchase, provided you're not buying from the hand-made boutique outlets - This is why I'd only go after a project like replica tanks with the moulds & flow-forming etc. Batch production would make a heck of a difference in final price. "Economies of Scale" & all that.

As for welding the thing back together, heck the original welding on the bottoms seams of these things is such a mess you'd HAVE to be an inexperienced welder to replicate the same effect. This is no "Row of Dimes" quality welding. This is a main reason why I believe they were torch & stick braze-welded with "Aerobraze" type rod.

There was also something said already about the taps on the petcock bung - Well I'D suggest that you cut the damn thing off as well, weld the hole shut, & find a NEW location for the thing! 'Cause there's a very narrow gap for this petcock between the valve cover and the carbs - And the differences in frame geometry between CB1100R and CB900F mean that to get that petcock to sit in the right spot, not to grind away on the valve cover, you've got to leave this huge long "turtle-neck poking out" (to paraphrase the Fat Bastard, 'cause it really does look like shit!) I've measured the distance from steering stem center to the vent hole in the center of my gas cap, (with the tank sitting in the only workable position on the CB900F frame) then asked CB1100R owners for the same measurement on their bikes, and found a discrepancy of something like an inch and a half. I checked the same measurement on a CB750F frame I've got on hand, and the distance was similar to the CB900F - the CB1100R chassis is just different from either of these two. And that's not just in terms of the tank mount, because the limitation being that petcock bumping up against the valve cover. It's probably an accumulation of factors, such as the CB1100R engine being mounted slightly forward in the frame, the steering stem angle, and the steering stem itself being "tucked in" further back, closer to the engine etc. Probably a half inch of this, a half inch of the other. The point being, however - that these are elements of frame geometry which you either "can't" change, or if you can well - you should just build an entirely new frame from scratch! Something infinitely BETTER - and you know, that would probably be easier than moving/tilting the engine & steering stem etc. - And for what? For the bung on that tank??? Ha-ha.

So - to mount the tank on YOUR frame:

You wind up having to either drill a hole in the frame's back-bone for a new through-bolt to hold the tank mount bungs, OR far preferably - make oblong tank mount rubbers up front (made mind with hockey pucks) AND fabricate a special mount for the rear of the tank or drill out either the tank or the frame - SOME "fabricators" over on the DOHC-4 sites have made one fuck of a mess back there, grinding away on both the tank AND the frame, leaving pointy shards of sheet-metal pointing this way & that. Their bikes look great with the tank and the seat on 'em but as soon as you scratch the surface ... well more like it'll scratch YOUR surface if you're not careful ha-ha. I've got some thin Aluminum plate (or thick Aluminum sheet?) which will incorporate TWO bolts, one to the frame, one to the tank - and then there will have to be two thinner sheets of rubber for vibration dampening etc. It's a lot of pissing around, yes - But I'd really rather not mess with the whole ... "pudenda" at the rear end of the tank. It's just so picturesque!


Definitely wouldn't want anybody to say that I'd "Reamed It Out" ha-ha. Not with all of the stories I've told on the 'F-orum, about taking long hot soapy showers with the thing clutched to my chest, rubbing it's back with a loofa gourd/sponge to "exfoliate" the sticky epoxy-based sculpting/filler primer which the P.O. had used to gel over the underlying Aluminum for that glossy paint job everybody seems to like so much.

Another one I don't understand, is how many CB1100R owners & CB1100R tank users have gone to the plastic caps with the lock & key - While on the one hand, I suppose somebody might steal your gas, heck I'D be more worried about somebody stealing your BIKE ha-ha. A far better security system needs to be put on these bikes, the type where you'd never need a tank lock or a helmet lock or a steering lock ever again! Yeah, THAT'S something to weld inside of your tank alright - a GPS locator! I'm going for one of these "ARMED GUARD" type systems with the pager/cellular-telephone caller, even better than a loud alarm heck I'd rather get there while the fuckers are still trying to dick with my bike. Of course, it goes without saying that a few remote disable switches should be par for the course. ANYWAY my point being about the gas caps - Yeah, it's hard enough to find a good used let alone NOS gas cap for the CB1100R tank. Same deal with the petcock. Well the exact same black powder-coated CAP is off of the XL500 & there are several other versions of it in silver etc from the XL250 or XL185, even some alternate versions that'll still fit. I got mine as an NOS XL500 item but I should just as well have grabbed a beat-up silver one, 'cause I sanded away the powder-coat and polished the living hell out of it with 3000-"grit" grade paper/foam, then some "Mother's" alumimum & mag wheel polish - This stuff works better on the STAINLESS STEEL that all of these gas caps are made out of, better than it works on the Aluminum it's recommended for. Guess I should grab some stainless polish for the tank itself. Polished up my old CB1100R petcock too, but it doesn't vacuum seal perfectly between the reserve tank and regular tank flow. "OFF" works great, but I just don't wanna get stuck out in the middle of nowhere 'cause my reserve ran dry! Then again, it's only a slight "leak" - and only under vaccum/pressure at that. Might not leak at all. However, there ARE other bikes which this tap came off of. One of 'em was a DOHC-4 750 but I forget which. It's either an 'F or a 'K and I think it's either '79 or '80 vintage. But they're out there in numbers. I've done some searching for an alternative petcock which points it's hose barb at a 90-degree angle from the valve switch/lever, 'cause then it could be rotated such that the lever points to the rear while the barb & hose points inward toward the carbs. As the OEM switch sits, the barb points to the rear of the switch lever. As such, you can't really rotate the thing around to avoid contact with the valve cover. With the valve rotated that 1/4-turn and the barb still pointing inwards, this should be able to "buy" an extra INCH of forward movement of the tank. OR, conversely, perhaps a PINGEL fuel valve could be fitted. Ideally, with an L-bend pipe fitting, so as to move the valve itself toward the rear. I don't know whether it would still be feasible to use a RESERVE stand-pipe, but one supposes a few brass pieces could be brazed together with a bent stand-pipe after they'd been threaded together - with braze on the pipe threads etc so as to create a seal which wouldn't need rebuilding, such that the whole assembly could thenceforth be treated as one single part with no need to rebuild it. MAYBE this would work - If there's a valve with a removable stand-pipe with an O-ring seal of some sort, maybe THAT could be built, disassbled for cleaning & rebuilt, with a bent stand-pipe threaded through a threaded L-bend fitting. MAYBE. But of course, if you're going to go to all this trouble? Might as well cut off the damn bung and fit another one! Might get around to doing that somewhere down the line.

So it looks like a good bunch of the cool period-correct mods have already been done to this bike. The key would be to FINISH the job, only better than it was done originally. The fairing isn't stock, by the way. I'd love to see a few more pics so as to identify the thing. It MIGHT be worth some $$$ - The CB1100R seat definitley is. The builder here probably ran into the same stuff that's stymied ME on my own conversion - the CB900F with CB1100R tank can no longer use it's regular side-covers, 'cause the front top bung for the covers is on the OEM tank, so the bike now needs either DIY or alternative OEM covers. And then you'd need a different seat too, I tried to get this here Corbin "Gunfighter & Lady" (what a hideous name for a hideous seat!) from the donor bike's original "Freddie Spencer Replica" styling - but it won't fit correctly with the CB1100R gas tank. So ALL of the existing bodywork gets ditched from the original - that's why you see 'em all here together - and the fairing too, no doubt because of that "neck sticking out" thing at the front end, makes the "naked" style look really funny. I've wound up making a DIY seat from fiberglass, to be covered with the CB750K0 Sand-Cast "Duck-Tail" cover (to match with the wire-spoke rims, the "toaster-tank" polish on the alloy tank's sides, the whole "CB900K0 Bol Bomber" schtick - being an "Homage" to the '65 CB450K0 Black Bomber - the bike benefits from as many retro-fried flourishes as you could throw at it, & of those which would stick) It's just been a pain in the butt finding a seat-cover maker who can offer this particular seat cover in another COLOUR. The "25 colours & patterns" people seem to do every single OTHER Honda seat cover, just not this one. And they tell me they need an entire OEM seat from the Sand-Cast in order to make one. Sheesh! Now THAT ain't cheap! Well whatever - I'm just sayin' - there are all sorts of other options for fitting the CB1100R tank and making it play nice with the SEAT - but that existing piece of fiberglass you've already got has the best odds of working.

(I'd also point out that THIS is the reason nobody here could figure out whether the seat pan was "real" or not - whether or not it's real isn't the point, it's whether any of the OEM mounting hardware for the CB1100R itself, would be of any use to you when you're fitting the thing onto an 'F-bike! Right?)

HMMMM - looking back at your pics, seems to me you've got a CB750F frame under there. Which is GOOD - I was just going to suggest it! The CB900F frame isn't anywhere near as stiff due to the rubber mounted engine - And what's worse is the CB900F frame was built with thicker heavier tubes, but without giving any stiffer of a frame! I've got an old fire-damaged CB750F frame still kicking around. Sadly, the bare frame which I had brought indoors for all the chassis modifications & then an engine swap from the bike outside, well - it was heated up by the house burning down around it and then the roof fell down on top of it and nearly flattened the frame. Its been three years and I still haven't been able to bring myself to take that frame to the crusher, being that it was my first CB750F and I'm sentimental that way - Gonna have to cut out the steering stem in case I ever want to build a modified EGLI style frame and still keep the original registration number - Hey, a bit of a cheat to be sure, but if all of those dudes out there are getting away with raked-out steering stems and hard-tail mods on THEIR frames? Well, I should think it makes even MORE sense to be able to register a frame with an open cradle or perimeter-frame type mods done to it - Ha-ha. No really though - If I kept the rear engine mounts and swing-arm pivot, would that make it any MORE legitimate? Ha-ha. And it goes without saying - this proposed EGLI style "spine-frame" with the huge backbone tube etc - It would be fitted with all the same OEM bodywork, so as to fly "stealth" under the radar! IMHO, it's a worthy project. Yeah I really ought to cut those bits out of that frame, stick 'em on a plaque on the wall like a pair of antlers ha-ha. Meanwhile, what I'm GETTING at here, is I'm hoping that the left side solid-loop frame rail could be chopped off from the one side of that damaged frame, and then welded onto the OTHER frame.

Then again, there are folks like Jim-Jam "JJAM" from the www.cb1100f.net 'F-orum, selling kits of donor parts to convert a CB750F frame to more of a CB1100R or BETTER specification. Cross tubes to weld above the swing-arm pivot and in behind the headers etc - and an insert to close up that right-hand-side open loop with a solid rail. the difference being, I guess you've got to remove your sump & oil path plate from the bottom, and the valve cover from the top, whenever you need to remove the engine from the frame or put it back in. Oddly enough, you need the engine in place while welding the whole thing shut. Makes you wonder - why not just make a frame that needs to be CUT when you remove the engine? Ha-ha. For all the times it'll have to be done, IMHO it might as well have a new tube welded in whenever the engine is done. I mean - for a street-bike it seems to make sense. I'm really not keen on the idea of those removable rails from the BACKBONE I mean wow - I'd rather have the backbone reinforced with one massive thick tube, and then have both of the bottom rails bolt out and the whole engine & bottom half stay on the stand while the rolling chassis stays in one piece. There was definitely a better way to do these frames, proven time and again by the likes of Magni, Egli, Bimota, Harris, Christian Fior, Moto Martin, Bakker - am I forgetting anybody?

THAT'S what I find so laughable about the comment "Leave the bars the way they were, they were put there by a Honda engineer"!!! Is that SARCASM? Ha-ha. I mean - WTF. These OEM clamp-on bars shouldn't even be referenced as a "Clip-On" bar, 'cause they sure as shit don't improve the ergonomics any. There were some really good OEM adjustable clip-on bars from the CB1100R & VF1000R & maybe some others - which used a "Hirth Spline" washer in between the bar & clamp. But functionally speaking, some cheapo Chinese clip-on bars should work just fine, only put a bar with a slight bend in 'em so you can pivot the bar in the clamp and get the correct ergonomics you're after - more to the point clearance around the fairing if you're gonna stick with it.

Oh - but I'm not saying you should stick clip-on bars with THOSE forks! That fin down the front & rear of the fork indicates it's a '79 vintage - as do your non-reverse type COMSTAR wheels which I'll get to in a minute. The '79 fork from CB750F was only 35mm, a European market CB900FZ would've had 37mm forks but I think that might have even come later, that in fact it was the '80 or '81 which had the 37mm, and that the '79 model still had only the 35mm forks. Either way, I wouldn't even recommend going to the 39mm forks as from the '82 CB900F OR for that matter the 39mm TRAC anti-dive forks from the '82 CB1100RC / '83 CB1100RD - Though there ARE some very good ROTORS on the CB1100RB '81 only, which are now available as a reproduction from METALGEAR AUSTRALIA
That's THIS one

As compared to
SOHC

Early DOHC

Later DOHC

Or any of the several other 276mm 5-bolt front rotors, such as CB1100F - yes the CB1100F even, only 276mm front discs!

It's a bit of squinting but it ain't just the black paint in the middle, or longer spokes/arms etc - the latter three images are scaled up a wee bit - So if you squint you'll see the center hole is smaller in the 1st image - it's a 296mm rotor whereas the latter three are only 276mm.

(((296mm and the same spacing side-to-side actually matches up to all sorts of Honda forks all the way through to the middle of the CBR929RR, up through the ST1100's - there are probably a few current-year Honda models with the same brake diameter. Which means this one, formerly 24-carat "UNOBTAINIUM", reproduction rotor - now gives you a TON of options while still keeping that same OEM look & matching to the Comstar rim, etc. AWESOME stuff.)))

Well HERE's the link to the CB1100RB reproduction rotors:

MGear Brake Disc Front L/R at Metalgear


You can search by the model AND by the rotor dimensions on their site, by the bolt-circle, by the center-hole diameter, by the number of bolt holes. VERY useful stuff. Too bad it doesn't back-track to give you the model names, otherwise I'd use it to verify old 2nd-hand stuff off of eBay!

There are ALSO the heavy vented CB1100R '82-'83 type rotors in 296mm, also from the GL1100A Aspencade & "pro-link" (monoshock) CBX six from '81-'82 - I wish to heck I'd known before I went out & bought mine. Of course, MINE were always slated for the wire-spoke rims I'm swapping over to, so the 9-rivet center carrier seemed like a good idea - well, NOW I'm thinking I'd like to re-drill the '81 version, dished, one-piece disc - with 6-holes for the GL1000 front hub. The '81 '82 '83 type twin-pot calipers can be slung from the OEM forks from GL1000, CB750F, CB900F, non-TRAC versions of GL1100, & the SOHC CB750F2 '77-'78 with it's spindly 35mm forks - which look practically identical to the 39mm CB900FC forks anyhow, so why KEEP them - with the caliper-hangers from the pro-link CBX - OR the gold painted version of the same part, which was used on the '81 CB1100RB - Somehow I'd been looking at pics of these bikes for YEARS and never realized - I had assumed it was an 18" front wheel with 276mm rotors.

ANYWAY, there are other forks which would be useful for these bikes - and going for the "Period-Correct" angle, I feel the TRAC anti-dive is such essential early-'80s Honda tech - it's like... Well the SOHC guys don't like to give up that swinging front caliper, you know what I mean? If THAT'S so essential to a correct looking 1969 through 1978 'K bike, well us DOHC-4 nuts should appreciate what all WE had, just as much.

One possible fork swap I've been contemplating a lot lately (up until I found a GL1500 front end locally sourced, picking it up next week) would be a 43mm TRAC fork - just like the NSR500's etc had. But the only 43mm TRAC fork on a STREET-bike, was from the '96+ ST1100-ABS model, and only on the right-hand-side. So - you'd have to have to figure out a custom caliper hanger for the left-hand-side leg. But at least the OEM caliper on the right side is already set up for the 296mm rotors. 43mm is the thickest fork allowed in AHRMA "Forgotten Era" racing -And the precedent was set by the Harris Magnum, itself a CB900F based kit-frame special, originating as far back as '81 or '82 - So if you want the bike to come off as either a contemporary racer OR one awesome period-correct special, 43mm is about as big as it comes either way.

Damn though - the ST1100-ABS fork with ONE TRAC unit could be pretty good too, though I'd really rather have the earlier calipers on it - The best most awesome front brake set-up would involve custom caliper hangers for the finned Lockheed opposed-piston calipers - at which point, if you're building special hangers AND you're willing to go that extra mile for the TRAC anti-dive - like say, if you were gonna fit calipers like that to a CB1100R 39mm TRAC fork let's say - well at that point it might as well be the ST1100-ABS 43mm fork, with two right-hand-side legs on it. 'Cause the caliper hangers are gonna be one gnarly bear of a project anyhow. Might as well go "full bore"!

There are are also two really choice options for a slightly less beefy yet all the more period-correct of a TRAC fork - The GL1500 is a 1988+ bike, yes - However it's 41mm TRAC forks are a near identical match to the works team forks from the '82 "CB750F" bikes which Freddie Spencer & Mike Baldwin & many others raced in the AMA Superbike series. A member over on the www.cb1100f.net 'F-orum has a good set of the original works forks, some great pics up over there of his restored forks on his 1123cc 140HP racer which currently races in New Zealand in competitions such as the Phillip Island Classic etc. Of course, there are also a few builds on the 'F-orum showcasing the GL1500 fork being used on other "Freddie Spencer Replica" builds. But I'D suggest using one on a CB1100R replica as well! Heck paint the thing RED or GOLD if that floats your boat - This is a 41mm TRAC fork with 296mm rotors and a 20mm axle, integral fork brace etc. Of course if you're worried about the front bearing swap from the 15mm OEM axle to the 20mm size, the GL1200 fork is also a 41mm TRAC anti-dive fork with 296mm rotors on most versions -AND it's from 1984- but it's got the same 15mm axle as the CB750F, CB900F ... and the '65 CB72 Hawk 250cc while we're on the subject of KEEPING that 15mm axle!

Personally, I feel that ALL of these old Honda bikes should be looking at an upgrade from the 15mm OEM axle to a 20mm replacement. Even if it means having the hubs milled out for bigger bearing pockets. (I think like that 'cause of these spoke hubs, but hey it should be done on a Comstar hub too, not if but WHEN you disassemble & rebuild your Comstar wheels!) It's not a cheap mod beefing up the front axle, but let's say IF you're all about the period-correct look, then you'd rather not swap out the OEM fork so you're capped out at 39mm forks, then yeah this is a HUGE deal, between a beefier axle and a fork-brace, the thinner lighter forks might just work far far better than a thicker beefier fork without 'em! - And the 20mm axle needn't be obvious from the exterior, either. You'd really need to bring out the vernier calipers & stuff, to figure out that it's been done. If you're not "allowed" to do anything else, then wtf, since it's a huge upgrade for a stiffer front end and better handling. If you check out the "Eurospares" photo album site, full of all those awesome vintage racers - There are bits in there all about beefy front axle upgrades for the period LAVERDA and other such "competition" on the Endurance Racing scene. which the CB900F is born from, hence the name "BOL D'OR - from the annual race in Belgium & France -

DOH! And while we're on the subject of European ENDURANCE racing, if you're already turned on to the idea of a CB1100R replica? Then you need to check out the RCB & RS1000!




http://www.honda-museum.com/wp-content/uploads/2015/01/1976_Honda_RCB1000-1-1024x683.jpg









So yeah - Like I was saying before about the pics of CB1100R and getting confused about the size of those rotors & rims, 'cause of the bigger rotor on a bigger rim well, they seem about the same PROPORTION to one another. These RACE bikes create similar illusions, 'cause THEIR brakes can be quite a mix-up, not only from model to model or year to year, but even between races - that, and there were several riders on these bikes in practically every race so you wind up with all sorts of personal touches in terms of rear-sets, perches & bars, dry sumps vs regular wet sumps vs DEEP sumps holding several Liters of extra oil - the front rim diameter or the rear rim width, AND the brake rotor diameters or the calipers they were paired with. It's a HUGE mix up, but IMHO makes allowances for anything YOU or I might like to do with our OWN builds. As for the brakes themselves, the AMA Superbikes had 310mm front rotors on some versions, 330mm on others from the same year (usually 310mm on 16" front rims & 330mm on the 18" fronts) and sometimes the RS1000 wound up with the bigger 310mm rotors on 'em, as when Mike Baldwin ran the RS1000 at Daytona. The RS1000 & later year RCB's had various sizes of rear rotors as well, all the way down to something like 210mm or 220mm on up through 296mm like the OEM rotors from '75 CB750F1 & GL1000 on through to the CB1100F etc - However, I THINK when you're looking at all of the early RCB models from the '70s etc, I THINK those are just 296mm front rotors, same size as the CR750 used as far back as 1970. There's really a lot of SQUINTING to be done, when one is considering a replica of this type! And of course, lots of research & asking questions etc. SFAIK, there weren't ay 19" front rims on these guys, though I might be mistaken. It's possible that some of the '81 AMA Superbikes might have used a 19" version of their MORRIS 7-spoke cast-Magnesium wheels. So too, there MIGHT have been a 19" front on the odd early RCB - I don't THINK so, but there might have been? I've squinted at literally hundreds of pics of these things, ruler in hand, comparing rims & tires to forks & rotors, rear rims etc. So far none of 'em have indicated a 19" front rim, and that's what I've heard from the RCB replica builders out there. Hence all of the early Silver non-reverse Comstar rims they're always building in 2.50x18" - That, and it's better for the steering, handling, weight bias, ALL of that geometry etc.

What I'm saying is that YOU should look at all of the options out there before you decide what to do with YOUR wheels, 'cause I really do love the look of those non-reverse "Silver" type Comstar rims, from the '79 only DOHC-4 bikes. Awesome stuff - Just look at the RCB & RS1000 pictured above - see anything familar? YEAH. Silver Comstars are awesome.

However the "Silver" non-Reverse Comstar wheels on THAT bike, which this THREAD is principally concerned with, would be 1.85x19" front & 2.15x18" rear. Which isn't very awesome. Same sizes as the '69 CB750K0 Sand-Cast. Notable that they'd "fixed it" by 1970, at least in the form of the CR750 RACE-bike. Should've done the same with the Street-bikes but WTF that's Honda for you!

More than anything else, this somewhat limits your tire selection. Don't throw 'em out just yet though! There ARE ways of dealing with 'em. Ways to make 'em AWESOME like I say.

Whereas if you'll squint you'll notice that those RCB & RS1000 wheels are 18" front and rear, probably 3.50x18" in the rear (from my best eye-ball guess, (an "educated" guess, what with having rear rims to look at for comparison here in the room with me, in 2.50x18", 3.00x18", 3.50x18" & 4.25x18") And from what I can TELL, from what I've heard, that's a 2.50x18" up front.

Well, that's what RCB replica builders use, a CB900F or CB750F rear rim on the CB400T etc 18" "spokes", maybe even the CB900F front hub if any differences are found) and the REAR wheels on those factory racers are very very different. I'd recommend looking at FACEBOOK of all places, at the "Caillou Bedier Racing" page where they're restoring a '76 RCB, plus another one I think it's "Classic Motorcycle Spares" in the Netherlands, aka "CMSNL" who are restoring the RS1000 - they've both got detailed pics of the rear wheels & the different hubs & stuff involved in each version. But I'm not gonna just SHOW 'em to you, 'cause there's waaaaay more awesome stuff to be found while digging through their photo albums!!!

Now, there IS a 2.50x18" front wheel from DOHC-4, not only the "Boomerang" front wheels from CB1100F, CB1100R '82-'83, the CBX750F & VF1000F "Bol D'Or" models, but ALSO one of the "Reverse" type: the front Comstar from the '81 GL1100 Gold Wing. However the "Silver" type wheel necessitates the wheel either be "weld-widened" or rebuilt with a replacement rim. Depending on which method, which replacement rim you use, that could either make the wheel very heavy OR - it could improve things immensely by lightening that rim a great deal. IF you can find the type of rims I'm suggesting.

DAMN it bugs me that I never noticed those dished, one-piece type 296mm front rotors from the CB1100RB! I guess I'd read all the stats always saying it's a 2.50x18" front wheel on the CB1100R - which was obviously referring to the BOOMERANG rims on CB1100R C/D models (Which are heavy as shit by the way!) Turns out the CB1100RB front wheel is actually a match to the CBX pro-link version of odd-ball sized "Reverse" Comstar rims - it's a 2.50x19", (wider than the 2.15x19" standard on most other DOHC-4 models of 1980 or '81 through '82 vintage.) And the REAR CB1100RB wheel was the gold painted version of the 2.75x18" reverse Comstar which can be found in black & silver form from the CBX pro-link '81-'82 -

I also feel it's worth mentioning - while the 2.50x17" rear boomerang from the CB1100F seems to demand premium $$$ from those who seek to upgrade their DOHC-4 to CB1100F standards, there was also the Silver boomerang rear in 3.00x18" from CB900F2 (fairing model) and both gold and black versions in 3.00x18" from CBX750F, VF1000F, VF750F, etc etc - The CB1100R C/D rear wheel is only 3.00x18" and the purported 3.50x18" rear was only ever fitted to the works team racers like Ron Haslam & others raced in 82 & '83 - IF ya'll think the CB1100F 2.50x17" looked cool at that diameter, or if you wanted to widen the thing - well the VF1000F & CBX750F "Bol D'Or" aka VF1000F2 & CBX750F2 etc - they had a black painted Boomerang rim in 3.50x17" - plus there's a D.I.D. center-flange rim in 4.00x17" off of a much more recent Yamaha Super-Tenere dual-sport or Adventure-bike etc. Still heavy as shit. Just sayin' though - IF a person were interested in a 17" rear wheel, it's also feasible to use the "spokes" the star plates etc - from the CB750A Hondamatic or GL1000 non-reverse Silver Comstar rear wheels, they've got the same size of hub & bolt-circle diameter, but they adapt the hub to a 17" rim. I really don't think even that 4.00x17" rim is worth it though. Not when it's gotta be one heavy damn boat-anchor of a rim!

NO - what you want are the AKRONT "NERVI" rims - they're no longer in production, but NOS specimens still exist and Marvic magnesium rims have 'em bolted up - There are later versions of the Marvic rims which use a NON-flange center rim, just a plain old un-dimpled Akront wire-spoke type rim - Well, I'd be curious about taking an existing 18" Marvic set, and spinning 'em down to the correct dimensions to bolt up to a 17" rim of that type, then the "NERVI" rims could go on the Comstar wheels, and the Marvic would be immensely improved for the type of applications we always see 'em on - crotch-rockets of the '90s, late '80s Ducati stuff, etc. Seriously - IF this mod could work, IMHO it would be a "Win-Win" for all parts (parties) involved.

Here's a CBX from The Netherlands, with Akront "NERVI" rims installed - an even more balsy move was that they stuck an 18" rim on a 19" wheel, when they didn't even have to - I guess they figured the '81 GL1100 front wheel, or even a later year CB400T, CM400 etc, wasn't worth the trouble?






LOOKS like around 2.75x18" with 3.50x18" rear or maybe even 4.25x18" rear? Very tough to say - I should scan 'em really large & see if the script can be read on the right-hand-side of the rims. They're stamped the same way as all other Akront & Morad rims - and at least it's the conventional fashion to align the script on the right. I don't think it'll ruin your wheel ha-ha, but it's the conventional way of doing it! I've seen a few wire-spoke rims laced up "backwards" by DIY-ers, here on this very forum IIRC.....

What's truly mind-blowing, is how the Akront "NERVI" were produced in all the same widths & diameters as the rest of the Akront range. Passed over the purchase of a 5.75x18" - should've bought it. But this means they had 'em that wide in 17" as well - between the GL1000 & CB750A & DOHC CB750K etc rear wheels in 17", plus the clear evidence that you can stick an 18" on a 19" rim - clearly, one should have no trouble building a set of Comstar wheels in 3.50x17" & 5.75x17" possibly even 6.50x17" - For CROTCH-ROCKET RUBBER. Heck I'd love to see that set of wheels on a modern CBR never mind what all it could do for a classic Superbike! Boomerangs on a VF1000R perhaps? WOW. I'm getting a CHUBBY for these hypothetical Comstar wheels.....

(Well, I mean at this point it should be obvious I've got an unnatural fixation with motorcycle wheels. But hey, I don't JUST look at the bike-porn - I google other types of porn, maybe ... 0.1% of the time!)

Here are some pics I've dug up of the "NERVI" cross-sectional profiles - I'd have to check the fine print 'cause the place I downloaded 'em from had 'em all mixed up, as such their stated weights from that site might be less accurate as well. Tough to say, it might just be a couple of pic files out of place.

But IF I've got 'em all right, here are some suggestions of 2.50", 3.00", 3.50" & 4.25" - I don't have the profiles for the "NERVI" types in larger sizes, however I've got the profiles for the regular Akront rims too - and the "NERVI" and regular profiles seem to match up either identically or close enough in the smaller sizes - So I would assume that even the Akront "NERVI" 5.75x18" which I passed over on eBay last year (having been unaware of the new 18" diameter Crotch-Rocket tires in 180/55ZR18, assuming instead that I'd be stuck with huge DRAG racing tires - ugh) was probably very similar to the profile of a regular Akront rim in the same 5.75" size. ANYWAY - check 'em out.



I've also got some slices from OEM Comstar wheels' D.I.D. brand rims, from the half-melted wheels from my 2013 house-fire. I'll have to dig 'em up, photograph 'em & measure 'em with a vernier caliper. One which is of considerable interest to me personally, is a slice from a 3.50x16" NOS "Super-Akront" (at that time intended for the "KZ440LOL") which I lost in the fire. 'Cause I've got another NOS in the same size for a FRONT wheel on my Bol Bomber, (plus another 3.50x16" drilled for a rear wheel) and a 3.50x18" drilled for a rear wheel which will wind up paired with a 2.50x18" Borrani up front, both of which set me back all of $50ea being used - I'll have to put 'em on a "Budget Build" project! Truly though - those 3.50" "Super-Akront" rims have gotta be the most light-weight rims I've ever held in my hand. They've gotta be a lot thinner than equivalent, later production, Akront rims. (Got a 3.50x16" from a '90s Triumph Hurricane, originally intended for the "KZ440LOL", for direct comparison between the two types.)

Well I'm sure if you take the time to look into the - I'm HOPING that the MORAD company, the new name-brand for Akront, presumably after some type of bankruptcy or some such? Well - I've written to 'em to beg 'em to haul their old "NERVI" tooling out of mothballs. I'll have to post up a thread about it, and post the e-mail addy, so that OTHER "Comstar Enthusiast" Honda fans out there might lend weight to the request? The Ducati F1 Montjuich/SantaMonica/LagunaSeca people seem to be crying out for more Akront "NERVI" rims for their OEM Marvic wheels - I'm sure they'd be looking for greater widths and possibly 17" diameter to replace their 16" versions too.

Consider if you will - I've got a couple of 4.25x18" wire-spoke type Akront alloy rims for my "CB900K0 Bol Bomber" project here, and I've weighed 'em up - And they come up identical (on my bathroom scale at least) to the 2.50x18" OEM rims, D.I.D. brand, from a disassembled CB750F/CB900F rear wheel. So following that logic, one could probably upgrade to a 3.00x18" front and 4.25x18" rear in Akront "NERVI" rims, and pay no weight penalty whatsoever. Furthermore, a 2.15x18" to 2.50x18" up front, with a 2.75", 3.00" or 3.50x18" rear wheel? Is gonna perform BETTER than the OEM wheels.

Especially if you use a 2nd front wheel in the back, with a bolt-up cush-drive etc. This is a really common mod racers used on SOHC wire-spoke wheels, plus if you look at the '76 RCB, it's got a bolt-up cush too. I'm planning to swap out the SOHC CB750F1 rear wire-spoke disc hub for a "Front Hub Trick" at some point. I'd actually like to put a DRUM on the 900 at some point.

Well - one decent upgrade for the rear brake which can be done relatively easily, would be to cut the dished one-piece rotor you've got, down from 296mm to 276mm, and use the rear caliper & hanger from the CBR1000F Hurricane. Conversely, one could also cross-drill the existing rear rotor & shave some weight. Like THIS one, available ready-made from those same METALGEAR people, listed for the GL1000 etc but will fit the REAR carrier also:


As an alternative to THIS:

or even THIS:


Well - the 276mm smaller rotor mod would be far more relevant when using the composite rotors with the alloy 9-rivet center carrier & the much thicker heavier outer rotor etc. Like on the SOHC CB750F1 wire-spoke, the CB900F & CB1100F etc with their slotted rear discs - Well the Metalgear AU people have a service for that one too, where they rebuild your disc with the new outer rotor plate, powder-coat the carrier, balance the assembly, etc. What interests ME is the 276mm discs from the FRONT brakes, GL1000 & CB550 etc, same 9-rivet pattern & same size of center hole etc (there are a couple of different sizes in these carriers, so not ALL of 'em match up, sad to say) and to order one with the zillion cross-drill holes crammed into it - now THAT could wind up looking "period-correct" for the wire-spoke hubs, and yet at the same time shave a ton of weight. Truly though, the dished one-piece discs are already that much lighter in the first place. So to cut THAT down, cross-drill it etc. With the "Front Hub Trick" rear wheel, to do it with one of the front rotors in 276mm, this could wind up weighing probably HALF that of the original SOHC rear disc hub - maybe even less?

Well the weights are pretty much the same, the disc hub & the Comstar hub - with the Comstar bolts they're about the same. I've got disassembled Comstar hubs from both front and rear wheels, and heck even WITH a bolt-up cush on the thing, it should still shave a ton of weight off that rear wheel. Furthermore, the FRONT Comstar has even smaller rotors available to IT - like the 240mm disc from certain GL500 & CX500 models - now THAT'S a truly modern compact rear disc brake. There's a five-bolt cush from modern DUCATI rear wheels which is just about as compact as the front Comstar hub itself - and all of this would hide behind the wheel's sprocket, so it shouldn't look TOO funny having modern parts back there.

Just sayin' - if you're gonna go to some trouble reducing the RIMS' weights, you might as well go after the rear wheel HUB weight while you're at it!

The trick being, when you're trying to do this with the WIRE-SPOKE rims, well there's a wire-spoke front FIVE-BOLT hub, from the CB750K DOHC models - but it's only set up for the one rotor. No holes on the other side. That, and it's got the really spindly center. Well, there's also the CB750P7 Police bike - which had the 'F2 '77-'78 fork & rotors, IT'S got the dual-rotor 5-bolt wire-spoke hub. But it's uber-unobtainium. Just doesn't exist out there - practically every country which the CB750P7 was exported to, they used the COMSTAR wheel. Canada insisted on wire-spoke, and SFAIK there were some in the Philippines also. VERY rare stuff.

So I suppose the "front hub trick" is better set-up with the 6-bolt hub anyhow, and use the cush cut out of a fire-damaged KZ750B conical rear hub that I've got on hand, drill the dished Comstar type rotor with the 5 extra bolt holes. Interestingly enough, the front Comstar rotors also bolt up to that same KZ750B/KZ1000A conical rear hub, it's just a FOUR-bolt hub and a 5-bolt rotor. Center hole and one bolt lines up, just like the rear discs from the Comstar & 6-bolt SOHC wire-spoke rear hubs, too.

There are a few other wire-spoke rear hubs that could work, maybe even a "Weld-Up Hub" mod, but heck I don't even want to talk you into a wire-spoke wheel swap. I'd really rather see a pair of top-shelf, competition-spec COMSTAR wheels. I mean, I've got a good 9 or 10 pairs of aluminum wire-spoke wheels to build here at some point or another, some really weird but awesome combinations - but I don't think I'll build 'em all before I try and build the COMSTAR version of which. Two pairs in particular - THREE pairs I guess - a 2.50x18" Borrani paired with a 3.50x18" Super-Akront which will get a DRUM rear hub for best weight savings, then a 3.50x16" Super-Akront with a 4.25x18" Akront around standard CB750F1 SOHC era triple-disc hubs, then a 3.00x18" that I wanna stuff a wire-spoke conversion of the GL1500 front brake into, paired up with another 4.25x18" Akront which is drilled for a Harley rear hub so it gets the "Front Hub Trick" - I suppose the big fake 4LS drum, "Faux-Leading-Shoe" would best be paired with a DRUM rear hub, but I think it'll wind up where the more compact two hubs wind up together and the two really huge hubs go together. Would be cool to use a CBX550F REAR hub with the wire-spoke conversion back there but it's VERY HEAVY. I could see something like, a skimmed out SOHC drum with the CBX550F 230mm disc stuffed inside of IT, if it's at all feasible. I dunno. A really compact & clean rear disc hub with a huge 4LS drum? Sounds like a Harley XRTT - Definitely not cool on a Honda. I've always figured on using the 4.25x18" with the huge rear hub on a V65 Magna/Sabre based tribute to the "CZ Type 860", OR a GL1200 ENDURANCE 'Wing, pseudo-replica of the "DLF-1000" GL1000-based racer from the '76 Bol D'Or & IOM-TT etc. Now either of THOSE would be a good use for the rear hub, but the V65 requires the 16" front rim, for the whole Interceptor vibe of it. So, maybe I'd wind up mixing 'em all around this way and that, but wind up with the "SKINNY" rims on the CB900K0 Bol Bomber in the end?

Well EITHER way - I've been hunting around for just the right Akront "NERVI" rims, to build an identical pair to EITHER of these other wire-spoke pairings. Such that not only the tires, but the brake rotors & calipers as well, could match up between wire-spoke & Comstar versions. That way, they could make for a really cool set of TRACK DAY wheels - for wet weather tires & dry weather tires. Or they could swap back & forth on tire changes on the street too, one season to the next, etc. I dunno what's gonna FEEL like the best possible set-up on the DOHC-4, but I suspect it'll be the "SKINNY" rims with the rear drum, as they'll be the same sizes as the CB1100R factory racers' Boomerang rims, probably the RCB/RS1000 rim sizes too - and they'd be the lightest of the whole bunch, too. Sadly, the "Super-Akront" in 16" from one pair and 18" on the other, can't be sealed up tubeless with aquarium silicone. They're very light rims though, so it probably more than makes up for the tube weight. Which only points out how awesome the lightweight "NERVI" version Comstar rims could be.

There's a really cool CB750FZ '79 Super-Sport on the 'F-orum (www.cb1100f.net) with a TURBO set-up, old's-cool skinny Silver non-reverse Comstar rims of the '79 style, however they appear to BOTH be off of a CB400T or thereabouts. I'd have to verify the size of the front though IIRC it looked like an 18" - but the REAR wheel is the true odd-ball. He's using the SMALLER rear drum hub version. Not just a CB750K sized drum, but a CB400T rear drum. Now - if one were to do a plug-type rear disc conversion, or stuff a lump of billet back there, or a carved up hub/core from a cast/mag wheel of some sort - that could be a really cool rear disc wheel. Personally, I'm leaning toward the "Front Hub Trick" with a period-correct cush-drive bolted to it, 5-lug type to suit the five rotor bolts through from side-to-side, maybe even a cush cut out of an actual rear Comstar disc hub. More like a damaged late-model CBR rear wheel. 240mm CX500/GL500 dished & slotted disc, to match the 296mm CB1100RB front rotors. This is the same set-up to use on ANY Super-Sport from ''77 through '82, though if it's upwards of 900cc's like my purportedly 985cc's re-built '82 engine, well then maybe you beef 'em up one more step maybe try & put a little more rubber down to match the weight? Tough to say. Maybe the 3.50x18" Silver rear wheel with a compact hub & disc is suitable for ANY Super-Sport all the way up through the CB1100F & CB1100R??? Depends on how you feel about period-correct tire sizes. Personally, I feel there's some serious wiggle-room there. And being that the old '81 through '83 1100 engine still blows away the NEW 2010+ "CB1100"? I figure the 3.00x18" & 4.25x18" is appropriate, given those are stock sizes on the new model - And yeah, I'm gonna ignore the "Type-2" entirely, with it's 17" cast/mag wheels. Looks like a cheezy custom job. IIRC, the first year, 2010 version, had a set-up something like 2.75x18" with 3.50x18" - So either way. It's not a HUGE difference in tire sizes, but I'd rather have the same tires relaxed with a straighter side-wall, than see 'em pinched in with a triangular profile that's gonna "cup" the treads etc.

This all depends on what sizes of Akront "NERVI" rims actually pop up on the market. This far I've passed over on 3.50x16" & 5.75x18", and missed out on a 3.00x18" 'cause I was too slow on the trigger. MIGHT be able to score a 2.50x18" right now, we'll see. It's not an improvement size-wise, but if the weight savings is substantial then it'll be worthwhile.

Like I say, it's my HOPE that Morad will be willing to run off another batch. But for that to happen, there'd need to be some consensus on what sizes EVERYBODY was gonna order. I should think this conservative size or close to it, would be the best to ask for. Maybe 2.75x18" & 3.50x18" would appeal to everybody on the DOHC as well as SOHC Super-Sport market? We'd likely have the CB1100R people on board as well as the RCB/RS1000 folk, a good chunk of the SOHC CB750F2, innumerable others perhaps even CX650T's could use the same rim-set? I'd bet we'd hear from a good chunk of the GL1000 & GL1100 crowd as well. Once they'd realize it's possible? Of course, it might be posssible to run off the same widths in alternate diameters, too - But I think the best way to go about it, would be to propose just the two different sizes of rims. Barring that, just the one - for rear wheels only. Heck, it's tempting to get a bank loan and just order 'em all myself. Of course, the best way to go about THAT would be to set up an on-exchange basis COMSTAR REBUILD SERVICE. Which would be a huge deal. I'd really rather just order some rims and sell 'em off, let people be responsible for their OWN wheel rebuilds. The cost to the end user would be substantially better that way.

Now as an absolute last-ditch option, I'm thinking of having a flange welded into some regular old Akront wire-spoke rims, un-dimpled type. They'd be slightly heavier for the weld material, and theoretically not quite as strong. Perhaps a beveled outer edge and a fillet type weld, then the air-gap between the two rings of welding should be minimalized. And of course, the flange would have to be made extra beefy so it could be machined down to the correct thickness and perfectly concentric to the rim beads themselves. A pretty big chore, to be sure. If anybody were able to pull it off successfully, they should whip up a whole batch of the things.

Seen a couple of the old composite Technomagnesio rims, it might have been a DIY job - they were of a type to be bolted to a "NERVI" rim, but were stuffed into a regular Akront rim instead. They had five little do-dads, "angled Aluminum channel" sorta thing, each of which was held to the rim itself with rivets or screws. Ridonculous method, surely they'd just come up empty-handed and fudged up their own DIY "NERVI" substitute. It's inspiring, yet at the same time a cautionary tale. There's also an Italian company making something similar out of CARBON FIBER - but I doubt they'd fit the way we'd like. Worth looking into, though I doubt they're even remotely affordable.

Now, if I could get a bank-loan for it, I'd order the whole damn batch from MORAD & sell 'em myself, one-by-one - A heck of a commitment, but not as bad it say, everybody wanted you to rebuild their wheels FOR 'em, with the powder-coat and the hardware & everything. At that rate, the costs would absolutely sky-rocket. Which is why I feel it should stay as a DIY thing.

If it's at all possible to avoid having to invest a butt-load of $$$ into it, to avoid becoming the "middle-man", then IMHO the way to proceed is with a PLEBISCITE or a CHAIN-LETTER if you will - I'll have to post a thread about it on all of the 'F-orums & Four-ums everybody with a SOHC 'F2 through DOHC CB1100R, CB900C etc - all of the GL1000 '78-79 & GL1100 '80-'83, a good chunk of the GL1200 folk as well, I should think at least SOME of 'em would consider rims in 18"/18" but if they could be made in other diameters and especially even greater widths then no doubt about it the 'Wing nuts would be on board - & CX people would go for this first proposed pair of 2.75" & 3.50", and the CMX450 people well SOME of 'em should be interested - there were also some early '80s MX-ers which used a wire-spoke tubeless rim-set with hubs similar to the CMX - and then there are the Yamaha Super Tenere crowd, plus the specials like ZED's & FZR's MARVIC rims, and the DUCATISTI - if they ALL get on board then MAYBE we could convince the Morad people. Could take a long time to garner all that interest so this whole plan has to get off the ground SOON!

COUGH - Well, in the MEAN-TIME, if your restoration's coming along nicely, then it would make sense to run a different pair of Comstar wheels. Nobody values these wheels at all, even the rare types will always be cheaper than aftermarket Cast/Mag boat-anchors, or wire-spoke wheels - SO if one were ambitious about it, yet not as patient as I am & you wouldn't want to wait around for the "NERVI" rims to magically reappear, it would be reasonably inexpensive to rebuild some Silver non-reverse early Comstar rims in 18/18 off of a CB400T or CM400 etc, using the '81 GL1100 2.50x18" OR for that matter a rim taken off of a later-year rear CB750F/CB900F etc wheel, plus the 2.75x18" from the '81-'82 Pro-Link CBX six - OR there are the $$$ Gold or cheaper Silver or Black BOOMERANG rims, 2.50x18" front & 3.00x18" - a smaller lighter rear Boomerang from XBR500 could be rebuilt, adapting a smaller hub like I was saying before. It's just that those D.I.D. rims are gonna cost you a serious weight penalty.

I HOPE to hell this bike's finished by now, or at least still in process, stuck in limbo at the very worst. Too many great projects go uncompleted 'cause people get their priorities mixed up, they let B.S. like career & family & health get in the way ... let alone finances....


-Sigh.
 

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Which pic links didn't display? AHA. Thanks for the heads up!

Well TRUST me - I should think, at least IF you've got some remote interest in CB900F or CB1100R, CBX, any other DOHC, or the SOHC CB750F2 for that matter, CX - COMSTAR wheels dammit - then you will find THESE well worth clicking on my links even if they DON'T display properly!

Like I was saying before, HERE'S one very interesting yet period-correct CBX with Akront "NERVI" rebuilt Comstar wheels, from The Netherlands (Holland)


http://i458.photobucket.com/albums/...ms rebuilt kosman comstar 225_zpsxrusox2g.jpg


Note the cut-down "spokes" here - a 19" Comstar wheel rebuilt as an 18"-er - from my collection of profile diagrams, I believe THIS to be a 3.00x18" front wheel:

http://i458.photobucket.com/albums/...sman Comstar akront nervi 230_zps9prrrztl.jpg

WOW!!! Though, perhaps this mod needn't have gone so far as a "two-fer"? I mean the cut-down spokes that is. Entirely unnecessary when the '81 GL1100 was 2.50x18" - but it DOES go to show you that an 18" front comstar COULD also be cut-down to a 17" diameter! Paired with the spokes from the DOHC CB750K or GL1000 17" rear Comstar wheels, and say a disc-brake/chain-drive HUB from a CB750F/CB900F etc, and of course the requisite Akront "NERVI" rims - one could concieveably construct a pair of 3.50x17" & 6.50x17" Comstar wheels!!! Heck you might not even need the relatively uncommon 17" rear spokes, maybe not even the 18" front - perhaps it's feasible to cut-down ANY of the reverse-type Comstar wheels to a much much smaller diameter? IIRC, the NON-reverse Comstar "spokes" might present some issues, but then again who's to say? Looking at the grinding at the tips of those "spokes" or "star blades" "Comstar Petals" if you will, perhaps even the '77-'78 CB750F2 SOHC early type Silver Non-Reverse Comstar wheels, complete with their plastic rivet protectors, could ALSO be changed in diameter. Of course, there are already 1.60x18" or 1.85x18", IIRC even 2.15x18" front wheels of this sub-category, coming from the CM400 & CB400T etc....
















Additionally, an Akront "NERVI" rim that I passed over on eBay a while back - 'cause it was too wide. 5.75x18" - At the time I was unaware of the new crotch-rocket tires in 18", 180/55ZR18 -


Here are some MARVIC wheels of the Akront "NERVI" type. I believe this set to be of the 18" variety and just that damn wide - conversely they might be 17" or even 16" - the point is, you've got options. ALL of the options if we can convince MORAD RIMS to get back onboard with this concept! I found these babies on eBay but couldn't rationalize the $$$ ... at the time:


http://i458.photobucket.com/albums/...nt 5.5x17 3.5x17 akront nervi_zps9pe2t9hz.jpg

-S.
 

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