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The Patina Flip Special - 1975 CB750F

169K views 1K replies 67 participants last post by  jaguar 
#1 ·
As part of the initiative for Jag and I to put good things back into this forum, I figured I would start this project thread. There are a lot of interesting projects in the archive and current that show the talents of some great experienced motorcycle people, but there really isn't one done by someone where a newbie could look at it and really get a sense of how to start where to look so that the sawsall is not the first tool they grab. My goal is to rehab this bike into running condition for a flip sale in March/April so that I may fund a more interesting and fun project I will be working on with Jag at a later date. Some of the many topics I want to discuss here are work-space, tools, project evaluation, project planning, all the basics that in the real life we had to learn the hard way. Hopefully, when a newbie comes to start and ask questions, we can send him this link and it gets him or her on the right track.

So Lets Begin!!!!!


Prologue:

Let me introduce you to our subject bike, a 1975 CB750F supersport:










Back in 2011 Jag and I bought a bulk collection of bikes from a guy in Flushing who needed to clean out his garage....



Jag and I purchased the 1975 CB750F, the 1972 CB350F, and the CBX. Jag got the CBX while I took the CB750F and the 350F. We left the Suzuki GT there because the guy wanted another $1000 on top of what we were paying for it and it just wasn't worth it to either of us.


I sold the 350 after a day getting it running and instantly turned this into a profitable venture. I won't disclose how much was paid until after the cb750F is sold just so a) this thread won't taint any potential sales, and b) I plan to document the costs associated with just getting a bike running and for sale for a flip.


So Let's talk about the bike. At the time I purchased it I needed another CB750 like I needed an asshole where my elbow is, but there were a couple of things that were instantly attractive to me. For starters, the bike carried a 1990 NYS bike inspection tag, indicating it was last legal for rode use back when I was still in high School. Back then bikes like these were just used 15 year old motorcycles that could be had for a couple hundred bucks at most and there wasn't any special collect-ability for 1969 K0's, or odd stock colors, or JDM imports. The most valuable had speed parts on them because in the race replica sport bike explosion that was still happening in the early 90's, go-fast was all that mattered. All I could afford back then were old 70's bikes and I got made fun of plenty for them. They were called "grandpa motorcycles" and "pedophile bikes" because they only other people that still rode them were older lecherous degenerates for whom the 70's had not ended and would hit on high school girls that hung out on plandome road despite being well into their late 30's/early 40's. Still there were a few of us who couldn't afford the latest greatest used death machine and we had to ride whatever 60's and 70's crap we could find in our friend's father's garages. This included old triumphs and other brit bikes by the way, not just the jap stuff but the jap stuff was truely worthless where as a triumph or a norton could still pull a grand or two. So what does that have to do with this bike? To me it was a time capsule, a look at what a used bike from the early 90's looked like in an era when I thought almost all those original ones would be gone. The only difference is back then this one would have still been running.

The other thing that was attractive to me is that this is what I remember a "cafe racer" being in that era. I mean we call it cafe racer but you could easily substitute hot rod, street racer, etc...in there. To the eyes of those looking 20 years later it probably doesn't look it, but trust me, this was a mildly hot bike back in the 1970's/80's and even in the 90's it would have been somewhat desirable. The biggest thing for me were the Shelby-Dowd wheels, which up until I purchased this bike I had only seen pictures of:


For those that don't know, sometime in the mid 1970's Carroll Shelby teamed up with Al Dowd, a longtime mechanic and racer with Shelby American to offer motorcycle wheels. Supposedly there is a really good chapter in Shelby's Authorized biography but I haven't read it. They only offered these wheels in a few sizes (all of them narrow even by 70's lester/Morris standards) and they carried a pattern similar to Henry Abe and wheels only in a 6 spoke instead of 5 or 7. Because even I hadn't see a set in real life I asked the seller what they were and he told me they were GS750 wheels - which goes to show you, even sellers do not always know what they have. I assumed them to be Henry Abe at first, of which I had seen plenty, but it was only after I got them home and inspected them that I realized what they were. Most cafe kids now would probably throw them in the trash for spokes, but I have to say having a set of wheels that marks these famous racing's legends only foray into motorcycle parts makes me kind of happy.

But other interesting parts are the exhaust which does not appear to be the standard cheap mac affair, but is beat to hell. If I had to guess I would say it is a motad or RC street system. Oddly enough I have a matching chrome pipe in my collection in way better condition that I also don't know the maker of, what are the odds? Also the bike has a Martek 440 ignition which was state of the art electronic iggy conversion when bell bottoms and 'ludes were still a thing, but were surpassed with the Dyna-S ignitons of the 1980's.

Finally the Lacquer paint job just drives me crazy. It is Candy black lacquer over small silver flake, over the original candy blue (without primer!!!! bold move even for the 70's). It is def showing it's age with numerous chips revealing the original blue below, as well as many cracks, spiderwebs, and other age related damage. At one point someone really cared about this bike but then it went through 20 years of neglect it developed a character that I loathe to destroy, even though I have an original candy blue body set for this bike with excellent amount of character. The seat is trashed but it was one of those 2 up "cafe racer" seats that has a bucket for extra rider support while keeping the passenger seat, and are often mistaken for King and queen chopper seats, Ironically I have one of those as well with only a small rip in it that I have contemplated using. The bars are the US stock bars but are tilted back to give the rider extra leverage, this was also a common practice since clubmans to fit the cb750 went the way of the dodo after the 1970's, and anyway they weren't comfortable to ride with and few guys I remember using them for bikes they rode everyday in the 90's. This practice has almost all disappeared since, it looks kinda dumb, but it worked and you could get awesome leverage when you leaned forward through the bar's rise. It also has the NYC FIAMM horn mod - if you rode in NYC back in the day this was as close as you could get to air horns, and was really popular before the NYPD started handing out tickets to people who use their horn.

Condition wise, this bike sat closest to the door, and as a result it has some ugly corrosion to it as well.




but the brakes still work, as does the electrical and it's still pretty clean for something that looks like it was ridden hard and put away wet for 32K miles.

So, Like I said, we are going to take a beginner's approach to this bike and talk about the basics. I am going to update once a week but I encourage other members to add to this thread if they have a tip or trick or something they do differently than I do and would be helpful for a beginner.

Cheers and Happy New Years!!!!!
 
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10
#2 ·
A few more things I wanted to add:

why is this called the patina special? Well part of my rehab is going to show how to selectively preserve patina so that the bike looks used and has character without looking like junk. This is something that appeals to younger generations and quirky oddballs like me, all the guts in my parents generation usually look at less than perfect stuff and wonder why it isn't prefectly restored, but to me I like bikes that have an age and character because I don't feel like I can't use them in every day situations, and I like that my own scratches and general carelessness will add to the bike's character and story. The patina is basically the authenticity of this bike since I lack paperwork as to its history, and it took so long to create why destroy the beautiful parts of it? However there are ugly parts too, mostly in the form of red oxidizing rust that just make the bike look mechanically shabby when it may not be. So this is a lesson in selective preservation as much as it is rehabilitation.

Also, there are a few things I suspect about this bike, that I will discuss in greater detail when I get to project evaluation. For instance, the engine has obviously been out of the frame and at least partially torn down. The valve cover is chrome and the engine block is painted a slightly different shade of black from the head indicating it may have been off the bike as well. Lots of money was spent on this bike back when it was newish, so it wouldn't surprise me if I find that there is something other than stock engine internals. Cb750f's of this vintage (75-76) normally have silver engines and the fact that this one is painted black and appears to have been done properly (I.e. Not painted as a complete unit) so I'm kinda giddy about what I might find. I also might find broken shit too so it's all part of the adventure.
 
#7 ·
I'm with your parents on this one. I've always felt that "patina" was a cop out for not putting in the time, and effort into cleaning/painting/polishing a bike as well as you can.
 
#3 ·
So happy to see this bike being worked on.
Maybe we can talk about the smallish differences the super sports(f) have vs the K bikes more people come across.
 
#4 ·
We will get into the differences between the K and F in the evaluation section this weekend. It should be easy since I have a same year 75 K parked next to it in running condition. Part of knowing where you stand with a bike and knowing how to proceed is knowing how it should be in the first place.

This is going to cover a lot of basic stuff so I expect full audience participation. The next three sections slated for this weekend are "workspace", tools, and project eval.
 
#6 · (Edited)
So very, very, glad you are doing this Bike, I'll be following this one very closely because I have a black engine "F" lurking in the Shed waiting for a rebuild.
I was actually going to ask you for advice once I got started.
Thanks in advance.
 
#8 ·
The Factory black engine F's (1977-1978) are almost a completely different animal, sharing almost no internal parts with previous years. The pistons, cam, valves, head, block, trans ratios, and output shafts are all different and they even run a different chain and sprockets (630 instead of 530). Still they are a SOHC and the basics are the basics. I haven't decided how far into the engine I want to go yet. CB750's have notoriously high oil pressure and volume so it is extremely rare for the bottom ends (shell bearings) to even be marginally worn unless the PO was dumping the clutch at redline at every stoplight (and even then the chain and cases would give up the ghost first). There is a "surprise" which requires me to go into this engine but I'll talk more about that later on.

Even the chassis on those bikes are a little different. Remind me when we are talking about the differences in K vs F and I'll talk about the later F's as well. Frames, suspension, and fiddly bits are all different enough to cause headaches, but honestly of all the F's I prefer them. They are the fastest, most refined model of the SOHC species and the ones most easy to bring up to semi modern spec in the braking and suspension department.
 
#10 ·
Geeto...Certainly wasn't my intention to knock what you and Jag are doing. Different strokes for different folks I guess.
In your last paragraph you mention "fake patina", that's what I don't get. I've seen a few bikes with tanks resprayed to look very old, and rusty, what's that all about?
Showing my age I suppose:(
 
#12 ·
I didn't take it as an insult.

Fake patina, where to start? Oddly enough I have been reading Robert Williams' book on hot rods and there is a section that discusses this very thing. In the 50's hot rods and bikes were thrown together trash for the most part, but as the hobby progressed through the 60's uber clean shiny toys replaced the juvenile delinquent daily driver rattle traps. Then in the 70's guys like Williams and Pete Eastwood started building cars like they had been doing in the 50's - rough raw hot rods that could be daily driven. For some reason this was seized by the next gen hot rodders and became the rat rod movement.

So basically fake patina is creating something that never was so a bunch of kids can pretend they are in an era they totally missed.

real patina or survivor patina is preserving what was already there as a monument to how things were.
 
#13 ·
Geeto, thanks for making this thread.
I'm not new to riding motorcycles, but I am fairly new to modification, restoration, and working on bikes in general.
I prefer bikes older than 1985, for various reasons, but from this forum I've learned more about the actual idea behind a cafe
racer, more than taking the fenders off and putting checkered tape on the gas tank, and from this I have been able to actually improve my motorcycles, rather than just doing shit that will make hipster think they look cool.
But as such, I've found myself riding bikes that look mostly stock, but handle and stop better, and might have a little done to improve the acceleration. My new/old cb350 is going to remain stock other than some new avons, progressive springs and shocks, and whatever I can afford to improve the engine.
Since you are the first to tell people their bike could never be a cafe racer, and that people's attempts at turning sub-par shit into even more mediocre piles of dog vomit look like shit or whatever, I'm looking forward to seeing what is acceptable to you when it comes to putting an old garage find bike back on the road or track. This forum, including this thread has been very educational for me, and I look forward to learning even more about how to keep a 40 year old Jap bike from sucking.
Thanks!
-Eric
 
#14 ·
I don't just slam people for the sake of slamming them, there is a method to my madness. The issue I have with a lot of the newbies who start off on the wrong foot is that they make too many assumptions and forego the existing knowledge base and inadvertently set themselves for failure rather than success. Hopefully I'll be able to contribute to correcting some if this with a primer on how to go from a non-running pile to the point where useful modifications can be made. I'm going to be frank here and say if you are expecting me to do a lit of mods to this bike you may be disappointed, my goal is really to cover the beginning steps so that the bike is a bike and not yard furniture.
 
#15 ·
I get that, man. Every bike I've ever had other than my r1 track bike have been some barn find waiting to be scrapped, and even if they weren't something that fit in as a cafe or whatever, I'd still rather fix an old bike and ride it than watch it rust.
I think of my bike finds, and your current 750 project as a resurrection or salvation from a shittier death than being ridden to death or god forbid, actually being worn out. I've only ever ridden a couple of bikes I didn't enjoy, and they were both chopper style cruisers (Harley and a virago). So it takes a special kind of suck to keep me from wanting to pull one out of the dust and do what I must to get to blast down the road on it, and in the Case of my xs850 that can't be a track bike because it's shaft drive(or whatever the fuck, lol, I see bimmers and guzzis on the track all the time), I enjoyed it for a while, and now I have a buyer for it, and I'm doubling my input, so it wasn't a bad venture after all...
 
#16 ·
Interesting thread! And have thought about (and been asked to) doing similar in the past and more recently on three bikes I am working with at the moment namely 56 Manx, 57 T140 Triton, 62 Norton 88ss - from GP racer to café racer sort of thing, all old style type projects and just about to start the builds all at the same time.

I always end up at the same point and ask myself a question, (Geeto) how do you find the time to write this stuff? Sort of envious that you can as I cannot.......

Apologies in advance just in case you have mentioned this above somewhere, what are you going to build, soft tuned and pretty or all out 350lbs and +90hp?
 
#17 ·
Between the kid and the hobby it's tough, which is why most of my posts are one liners. I have an English degree and have worked as a writer so I just get the conversation going in my head and let it come out my hands, but I don't proofread and put very little thought into it beforehand which is why my posts are rife with errors.

Its going to remain mostly stock weight, I'm probably going to do the usual changes that I do to these bikes that makes my riding expirence better (superbike bars, bar end mirrors, GT grips, etc), but I am not reinventing the wheel here. As far as the engine goes, haven't decided the state of tune yet, and that all depends on what I find inside the engine. As I mentioned before, the engine has obviously been out of the frame and apart so I'm kind of excited to see what's inside. I have a decent amount of speed parts but am reluctant to use them because they are worth more as sold parts than inside the bike. I'm also on the fence about some of the other stuff I have, I have collected some rare Supersport only 1970's speed parts (like rear sets) and am debating on whether to put them on the bike or wait for a bike I don't intend to sell.

The real goal is to be a primer for newbies who have already bought the non running bike and to show them how to proceed without taking the bike completely apart, which is usually a death sentence for their projects. Too many of them snowball into bad decision making one after the other till the bike they once had is worthless. We talk all the time about the proper way for the newbies to proceed but maybe it's time to show them as well and why.
 
#18 ·
And jalsteve, I am way more envious of you and all the cool race bike stuff you do because I lack the training and tools. I'm am literally reduced to working with hand tools only as everything from the blasting cabinet to the drill press is in NY.
 
#19 ·
Blasting cabinet in a build shop? No way as too much crud gets thrown around = Two workshops one with all the cutting tools and one for assembly. In years past one workshop was my bedroom and the other was the kitchen (no blast cabinet though), it helped that dad was a petrol head and mum had buggered off.

Off piste a bit, a little bike just in for full rebuild. Ridden by Alex Criville in 1989 to win the World 125cc Championship. Land vehicle Vehicle Sports Racing Grand prix motorcycle racing
Land vehicle Vehicle Motorcycle Motor vehicle Car
 
#20 ·
My father and I setup his garage as our primary work shop. Single lift, oxy torches, 220v compressor. Blasting cabinet was on wheels, rolled it out the door, closed the door, and then blasted. We have the usually vices, drill press, grinder, buffer, etc. two workbenches also. Used to be able to get a car in, now it's so filled with blown apart motorbikes, I can't even get to the second work bench and the first one is filled to the brim with norton parts.

That 125 is teh sex. Even love the Marlboro livery.
 
#24 ·
It was a 380 I think and it was pretty raunch. It had been sitting equally as long as the other bikes and didn't really inspire confidence in the crank seals. It had nice paint, but the pipes had dipples of rust all over them. It was pretty low mile at 10K and change, but he was solid firm at $1K for that bike and neither of us saw any value in it. If he had dropped to $500 I might have done it, but remember we were originally buying for a flip and $1K was high retail on a small bore suzuki two stroke triple of questionable engine integrity. Had it been a 750 I would have given him the money on the spot.

it's the third bike in the background of this pic:
 
#23 ·
That is excellent work.

I'm getting around to the nortons. There are two problems to them, 1) they are 9 hours away in NY, and 2) we are still researching them. The one is an original 1972 Dunstall 810 MkII, which as far as I can tell my father and I are the second owners on. The problem is that although it has a race history here in the states, the bike came with spotty paperwork. Trying to piece it's history together now, but some of that involves contacting the archives in england and waiting months for a response.

Just in case you weren't here when I posted about the find a couple of years ago, here are the pics I took of the bike sitting in the seller's living room:



The bike itself is a pretty proper bit of race kit, as it came with a Quaiffe 5 speed trans, and all sorts of strange markings on the engine cases including one that said production racer. I've run the vin and the bike is not an actual factory proddy racer converted to a dunstall. If you zoom in on this pic it is on the pad on the bottom most portion of the engine:


I don't know if you can see it here but on top of the dunstall work to the head the bike has had extensive port work:


As far as we can tell the bike was one of the few MKIIs delivered without the dunstall fairing or clipons (it has a euro bar and standard headlight, at least according to the 1972 pic of have of it at the New York Harbor coming off the ship). So far the only pieces we know are missing are the 18" borrani alloy rims (we have the hubs and spokes, but no rims), the sidecovers, and the seat. we were able to pick up a correct yellow seat and another body set in orange (repainted over the red).

Since I have your attention JALsteve, what do you think of this neck tag:


I have had four norton "experts" tell me it's the real deal, and then one dipshit try to tell me that it could be easily faked since those tags are common and I don't have the paperwork to back it up (same dipshit also made a lowball "serious" offer to buy after saying then and me telling him not for sale).

As it is a 1972 this is the year before Dunstall started importing his bikes to the states. This bike was personally imported by the "first" American owner. I phrase it that way because the bike came with an english license plate mounted to the dunstall forks (not as a ped slicer) and it could have lived a life before being imported. I know nothing about english road licensing, but could this be traced?

The other norton is basically a carcass left over from the dunstall spares. Included in the boxes was a set of 850 engine cases, barrel, and head, a commando 4 speed gear box, and a complete stock disc brake front end sans wheel. At mid ohio I picked up a 1971 commando frame with dubious racing origin (frame was braced and the rear hoop was hacked to fit a bumpstop seat), and an interstate tank. The dunstall came with 3 different carb setups (mukuni, stock amals, and Amal GPs) so whatever I don't use for the dunstall will go on the engine.

We also got this 650SS engine and tranny in the deal as well, but other than polishing it and putting it in my father's study as a piece of art we have no plans...yet:


The Dunstall is a father and son project, though my pop is turning 71 this year and is really hot to get on the project since he is about to retire. However we still need to get through my ironhead (needs, a battery, finish the front end dual disc conversion, and paint) and his BMW (basic service after sitting). I'm going to clean out some of my honda stuff, and get some of the projects off my plate and hopefully this year sees at least one norton return to the road.
 
#31 ·
Hey Kevin,

Thread Hijacks are common around here. Ironically enough I have a body set painted those exact colors and scheme. I'll post a pic later tonight.

You have either a 1977 F1 or 1978 F2. What's toast about the engine? The only factory issue I am aware of is that honda dropped big valves and a high lift cam into those heads without beefing up the valve guides so they tend to wear the guides and smoke like a chimney at around 25-35K miles. Bike still has the stock 4-1 and the stock carbs on it. Aribox is missing and because of the change in carbs to those years it is a 77-78 piece only.

I don't know what your exchange rate is like but dynoman is about the only place that had engine parts for these bikes:
DYNOMAN PERFORMANCE - Austin, Texas

Jag is about to do a thread in the tips and tricks section about brake upgrades to those forks (dual piston), and I can tell you the wheel setups to get it handling better (hint, 18" boomerang comstar front, and VFR dymag copy rear).

I don't know why your bike has DOHC cb750F front blinkers and interceptor rear blinkers, maybe it was laid down? Otherwise looks like a solid start to a project.
 
#36 · (Edited)
All to do with moving the oil scavenge arrangement on the mk2 (72/73 models). The early commando was basically an atlas tilted forward for the mark 2 Norton dispensed with domi style scavenge and altered the scavenge position but it didn't work well and the engine would wet sump at high speed.

The breather accesses the upper gallery, is there a none return valve in the breather?

TCed your right, interesting stuff though.
 
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