Another Noob from Canada - Ground floor of CM400 Project
Close

Another Noob from Canada - Ground floor of CM400 Project

This is a discussion on Another Noob from Canada - Ground floor of CM400 Project within the NEW MEMBERS READ HERE! forums, part of the Caferacer.net Forums category; Hi all. I'm a young guy looking for some knowledge as I embark upon taking a running, safetied 1981 CM400T and turning it into a ...

Page 1 of 5 123 ... LastLast
Results 1 to 10 of 47
Like Tree14Likes

Thread: Another Noob from Canada - Ground floor of CM400 Project

  1. #1
    Junior Member YoungSonOfaGun's Avatar
    Join Date
    Apr 2017
    Location
    Quebec, BC bound 2017
    Posts
    17

    Another Noob from Canada - Ground floor of CM400 Project

    Hi all. I'm a young guy looking for some knowledge as I embark upon taking a running, safetied 1981 CM400T and turning it into a cafe. 32,000km/20,000miles on it. Bike Runs ok, not burning/leaking oil, starts everytime, but its running a tad lean and feels quite sluggish (mostly at lower speeds so, pilot jet?). Spark plugs show white, backfires lightly when slowing down. Throttle response is a joke compared to my CRF250r (yes thats a race bike so not the same but still, the 400 twin should have more guts than it does). Guy I got if off was a geography teacher. Nice guy, tho not mechanically inclined. Bike hasn't seen a carb clean/tune in at least a year (when he got it) but the somewhat neglected condition it's in, my guess is years. Bike has had numerous owners.
    First order of business, I want to order k&n filters to replace the air box and a new exhaust so when I tackle the carbs, I'll be dialing them in to the right setup. Thats what makes sense to me, enlighten me if I'm wrong. Oh, I brought a comp tester to the sale, spot on 150psi both cylinders, figured that was pretty damn fair for an 81 with 32k. Getting quoted for a big bore kit but it will likely be out of my budget. We'll see. Oh, ya, I'm on a budget with this bike so bear with me! Picked it up for 800. Ballpark is another 1.5-2k on top of that as budget for now (yeah.. big bore is more of a dream at the moment)

    Thats the bike. About me. My old man is a hell of a good shit in the long run and an even better millwright/welder/fabricator. Before that, he was a mechanic, heavy equipment, mining/underground, etc. This is where my know how comes from. First car was a 1990 Crown Vic, 5.0L (302). Bought it half a year before I got my license and worked on it. We sanded the whole car down for a friend/body man to paint (couldn't have picked a bigger soab to do that to). With fresh paint, suspension, police interceptor trans, the 5L singing out of dual straight pipes from the mani, I'll never love another vehicle to the same degree, or debatably a woman for that matter.
    First bike was an old dirt scoot, 79 185xr. Still have it but thats another project for another day. The CRF gives me my fix for off road for now. This winter I stripped a 77GP440 sled to the frame and had to cut and weld half it's weight back on to restore the rotten rusted busted thing. The motor was mostly good and I didn't know how bad it was till I dug down, if you wanna ask why the eff I took the time. Was god time spent on the mig. Anyways. So thats a dumbed down quick shpeel about my experience. Mechanically inclined amateur mechanic, and "professional grinder, amateur welder." More experience on cars and trucks than bikes (87 ranger current daily). With an old man helping me out along the way in a shop we built together 2016/17.

    Why Cafe racer? Well, the bike has to be 400cc and lower for affordability of insurance/registration. And I like cafe's. Why do I like them? Grew up next to the coolest neighbour any guy could ask for. A gun collector, and a motorcycle collector who built and raced vintage bikes. Brian built his 2 450's from bottom up (my dad fabbed bars for him and the frame to a static bump starting system he dreamt up) with one thing in mind - to be the fastest sob on the track at Mosport. Where he still holds records. He raced those 450's in the 500 vintage class and often won. They were of his own design and they look like cafe RACERS.

    1st things I'm planning for the CM400T:
    Airbox - gone, K&N's to replace
    New black Exhaust
    Carb kit, clean, play with jetting and synchronization (I'm going to be doing some learning here, for instance, my carbs read "VB22 D B T B" see pic. Read that "1980/81 CB400T uses VB22B with 70/110 jetting". Does my ID# stand for VB22B's? Theres a box around the first letter B so I think thats the ticket but I cant find anything online to concrete it)

    Thats enough for now. Afterall, this is supposed to just be an intro. Here are picsName:  IMG_20170418_201308.jpg
Views: 159
Size:  112.2 KBName:  DSCN1406.JPG
Views: 164
Size:  153.6 KBName:  Bike Pass.jpg
Views: 161
Size:  146.5 KB

    Let me know what you guys think. And my bad if I should have put some of this under a different category.
    Cheers

  2. #2
    Senior Member hillsy's Avatar
    Join Date
    Oct 2008
    Location
    Brisbane, QLD, Australia.
    Posts
    6,242
    Good luck ditching the airbox - those carbs are notorious for running like crap with pods. No amount of re-jetting will fix them either because it's to do with the air jets (which cant be changed like the fuel jets).

  3. #3
    Junior Member YoungSonOfaGun's Avatar
    Join Date
    Apr 2017
    Location
    Quebec, BC bound 2017
    Posts
    17
    Alright well, in search of making sure these Keihin's are VB22B's I found this tidbit from the noob nemesis:

    4th: throw your brand new carb kit away. They are a red herring for newbies to buy shit parts and in the end they cause more frustration than they fix bikes. you basically bought it for the rubber goods. Order the right OEM parts.

    5th: Don't try to mod anything. Put it back to stock and attempt to get it to run. If you are being a dipshit and putting pods on it, save that for after you get the bike running right with the stock airbox. trying to jet a bike that isn't running right is just stupid.

    Alrighty then. I'll focus on taking the carbs off as is and getting it running mint first thing. And then I'll put my dipshit pods on! Really though, what can I do to get the fat airbox out of there? My top 2 priorities are reliability/performance and practicality - I'll be driving this bike. All the cafe's I've found online, and I've been looking pretty obsessively, the majority use pods. To the point where I was under the impression that removing the airbox is cafe 101. That said I haven't been searching for cafes from 40-50 years ago. Shed some light here plz, what are my options?


    EDIT: Saw your reply hillsy after I finished writing mine. VB22B's no good, any idea of what I could replace them with? I found some mikuni VM32mm's brand new at $190/each CDN. Be nice to find something a little cheaper, or the same ones used. Any idea if they'll work with no airbox?
    And can you confirm if that code is indeed for VB22b carb?
    Thanks
    Last edited by YoungSonOfaGun; 04-18-2017 at 10:54 PM.
    1981 CM400T - Cafe Project
    2006 CRF250R
    1979 185XR - I'll fix it in my next life

  4. Remove Advertisements
    CafeRacer.net
    Advertisements
     

  5. #4
    Senior Member hillsy's Avatar
    Join Date
    Oct 2008
    Location
    Brisbane, QLD, Australia.
    Posts
    6,242
    The factories didn't spend all that time and money on creating airboxes because they didn't work. They make the bike run well. Period.

    Just because you see a bunch of photos of clowns pulling off airboxes doesn't mean those bikes run well. They do that for a "look" in most cases and it is well documented that the CM carbs run like crap with even really good quality pods.

    If you really want to run pods you might want to look at VM carbs instead of the CV carbs you have now, but you'll have to open your wallet and play around with jetting for the next 12 months.

  6. #5
    Senior Member Stephen J's Avatar
    Join Date
    Jul 2015
    Location
    Ontario Canada
    Posts
    908
    Ya know with everybody yanking off the airbox to pod it up you'd be doing something original and different by leaving it there. To top it off your bike will run better than the pod squad. Win win..... Besides the right paint scheme can make anything look good.
    YoungSonOfaGun likes this.
    If you can't pick it back up, don't ride it.

  7. #6
    Junior Member YoungSonOfaGun's Avatar
    Join Date
    Apr 2017
    Location
    Quebec, BC bound 2017
    Posts
    17
    Alright, I'm considering what you're saying here. Keeping stock carbs = difficult to ditch airbox. Burning $450 on mikuni's is a serious chunk out of the budget. I'll keep an eye out for a better deal but for now, I'm going to clean these Keihin's and get the bike running mint.
    Thanks
    1981 CM400T - Cafe Project
    2006 CRF250R
    1979 185XR - I'll fix it in my next life

  8. #7
    Senior Member Geeto67's Avatar
    Join Date
    Oct 2005
    Location
    Columbus, Ohio
    Posts
    22,739
    Here is some food for thought:

    - I honestly think these are kind of terrible bikes to make into a racer, but every time I say that Farmer John posts pics of a bunch of weirdos in california who used to race cb400T hawks in the 70's and 80's. Why are they terrible? well the aftermarket for them dried up long ago, there isn't really a current knowledge base to work off of for how to race prep one, and they are one of honda's weird experiments that I will discuss further in a moment. A lot of newbies buy them because they are cheap, but they are cheap for a reason. What they are really great at is being plucky little commuters that you rack up serious miles on while getting 40-60 mpg and learning not to be killed by some dipshit in an SUV on his phone. Anything custom you want to do to this bike - you are probably going to have to fabricate.

    - the honda diamond frame: ick. The frame on your bike is called the diamond frame design. This was one of honda's early attempts at a stressed member frame in a mass production motorcycle, and while it was a pioneer and lead to a lot of more common stressed members elements (and a bunch of not what to do) later on, nearly EVERYTHING on the frame or that attaches to the frame is structural. So when you see those dipshits that hack the back shock mounts off and mono-shock it with the original swingarm - they are actually building a less structurally sound motorcycle than it was stock (and probably worse handling too). The frame was used on cb/cm400s, cb/cm 450s, hondamatics, and the cx500/650. There is an evolution to the diamond frame.

    This is what your frame looks like bare:
    Name:  honda-cb400ti-1978-canada-frame-body_bigma000111f29_e178.gif
Views: 142
Size:  142.3 KB

    and this is a fiche of the 1982 cx500 turbo (and euro sport model)
    Name:  honda-cx500t-turbo-1982-c-usa-frame_bighu0185f7c31_37f6.gif
Views: 148
Size:  136.7 KB

    See all the reinforcements and design changes they made to strengthen the frame once honda converted to monoshock (called pro-link) and decided to actually make the thing handle? Its a lot different right? Pay special attention to the swingarm pivot reinforcement and the subframe connectors that went from curved steel to welded joints with gusset plates.

    I mention all of this because I get the feeling you have the angle grinder already buzzing in your hand and you are read to just hack off the rear subframe to fit your way too cool cafe racer seat. But I want you to take a long hard look at what's going on here and realize that for everything you "cut out" of your frame you have to have a plan to put back in to maintain the structural rigidity.

    I will tell you that in the US we got the GL500 silverwing (and the cx500 turbo) which is a good donor if you want to convert your cm400 to a monoshock using factory parts. Just remember that the CX/GL500 engine is shaft drive so the swingarm a) will not work with your cm400, and b) is way beefier than a stock cm400 arm.


    - Bolt on upgrades: Just because you own one of the most worthless and unloved boring commuter bikes ever made doesn't mean you are SOL when it comes to upgrades. Honda did a lot of parts sharing back then and it's possible to pillage some of the stuff if you do your homework. One of the areas these bikes could use a serious upgrade in is the brakes department. Meet the cx500 european sport model:


    Name:  IT2J6579-01.jpg
Views: 138
Size:  249.3 KB

    See that beautiful dual disc front end with silver boomerang comstar and dual piston calipers? I am fairly certain you could use that whole thing stem to tire on your little cm. The problem becomes where to find one? I suppose you could look for a cx500 turbo being parted out and buy that front end but I betcha that will cost ya. Or you can figure out what other models used the same calipers, forks, etc...and piece it together with much more common stuff. Partsfish.com has a neat function where you can look up all the applications by part number, so when you get the part number for something you can figure out the cheapest source for it. dual piston caliper dual disc brakes with an 18" comstar wheel would be a pretty great setup for your little cm - you might even be able to out-stop that Honda Odyssey minivan that just cut you off.
    YoungSonOfaGun likes this.
    Ever tried. Ever failed. No matter. Try Again. Fail again. Fail better.

  9. #8
    Senior Member drgonzo's Avatar
    Join Date
    Feb 2008
    Location
    Rome, GA, USA.
    Posts
    1,167
    Just put some superbike bars on it and some good tires and ride the snot out of it.
    Geeto67 and YoungSonOfaGun like this.

  10. #9
    Junior Member YoungSonOfaGun's Avatar
    Join Date
    Apr 2017
    Location
    Quebec, BC bound 2017
    Posts
    17
    Thanks a lot for the feedback Geeto. I was talking with my old man about the stressed member frame(s) while looking at the ad(s). He's never been a big fan of them but I found a schematic like the one you attached and we figured alright, its manageable. Perhaps you'll cringe to hear I just missed a deal before I picked up the CM on a 1984 GS400s that had less miles and looked mint for the same price (800). I dug the frame on it and the larger tank as well as the gear driven counterbalancers. Some bad reviews on the anti dive unit Suzuki introduced on the front fork that year but I'm not racing it so I was willing to live with it/remove it if poss. Enough about the white buffalo. I did find a pic of a CM400 cafe that reassured me this bike can actually be something other than a geography teacher scooter (I was sceptical at 1st of the curved subframe connectors). I have plan A and B plan right now for when I get there, depending on what happens with the airbox. I'd be comfortable in leaving it mostly as is, trimming up the tail ends a bit behind the shock mounts, fabricating a cable tray for under the new seat to hold electrical. And the seat itself.. can wait right now, I haven't decided on going with the traditional racer seat or having the option of a passenger for short scoots, leaning towards the latter. Other option is fabricating custom subframe like you say, gussets were brought up to me by my dad as well. I'd be comfortable fabricating it, with him giving me a hand, it'll be as strong or better than stock. Option B there might make my life easier with the cable tray and hiding a dry battery but like I said, lets just see what happens with the airbox first!
    Found a youtube video of a cafe by 2 guys in Brazil where they built a CB400 into a mono without reinforcing/replacing the stock swingarm. Beauty looking bike they built but one good pothole and I dunno.. never been to brazil but I'd be a little scared to drive that thing where I live (Quebec = worst roads in Canada). The stock duals take the impact at the axle and transfer that energy straight into the shocks. Makes sense. The mono they had looked sketchy requiring the swingarm to standup to stress it wasn't designed for with no (negative) mechanical advantage and no reinforcement. The mono idea was scratched from the list pretty early on the drawing board, I'll be alright with the duals. It also had no rear fender combo'd with.. screen pods? (see pic, i dunno what those are called). Though the kawi GTR USD forks front end they put on it and upgraded brakes w/spoked rims are pretty legit, and the rearsets with those bars. How about the high profile tires? Not sure what to think there.

    Brazilian.. cafe cocktail:

    Name:  cb400 brazil.jpg
Views: 126
Size:  160.3 KB

    Also, I got a private message about a pair of used Mikuni VM32's off a Suzuki T500. Are they compatible? Looks like I'd have some tinkering with the choke lever being on the carb than the plunger next to the speedo but I'd consider just removing plunger/cable. One less thing as Forrest Gump would say. I'm thinking mikuni's would be an improvement after a phone call with my old neighbour today and from what hillsy said. And does my stock throttle function via cables? I read something strange (to me) about vacuum throttle lines instead of direct cables. Pic:
    Name:  VM32's.jpg
Views: 119
Size:  753.2 KB

    Let me know what you think and thanks for the replies. It's late now, I'll have a look into a different front end tomorrow for the drawing board.
    Cheers
    Last edited by YoungSonOfaGun; 04-20-2017 at 12:24 AM. Reason: Added wrong pic
    1981 CM400T - Cafe Project
    2006 CRF250R
    1979 185XR - I'll fix it in my next life

  11. #10
    Senior Member hillsy's Avatar
    Join Date
    Oct 2008
    Location
    Brisbane, QLD, Australia.
    Posts
    6,242
    OMG that Brazilian thing....if it doesn't shake itself to death with the unbraced swing arm it will probably shoot the rear shock up you ass with such a flimsy top mount.

    Then again, it probably doesn't get ridden......
    YoungSonOfaGun likes this.

Page 1 of 5 123 ... LastLast

Sponsored Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Similar Threads

  1. First cm400 project what do you think?
    By PA J in forum Project Builds
    Replies: 14
    Last Post: 02-03-2015, 01:57 PM
  2. 1980 cm400 Cafe project.
    By bigman664 in forum Project Builds
    Replies: 8
    Last Post: 07-29-2012, 07:28 PM
  3. New Project - CM400
    By theteacher95 in forum Project Builds
    Replies: 0
    Last Post: 06-21-2010, 10:15 PM
  4. Project II: Honda CM400
    By 2smokeTyler in forum General
    Replies: 0
    Last Post: 04-23-2008, 12:59 PM
  5. Garage floor paint
    By ahracer1 in forum General
    Replies: 9
    Last Post: 04-14-2008, 10:18 PM