Sideswipe's '81 CB900 Bol d'Or

Sideswipe

Active Member
So time to finally put my bike up and start the build thread!!

a couple of months ago I went out to a place called Gulgong (aka the middle of buttfuck nowhere) with this wierdo who calls his bike 'lola' (has his own thread) to pick up a bike, and here she is!!

When we originally picked it up it was a trailer job, it had been sitting on a farm for a while and needs a bit of TLC.. the electrics had been flooded at least once, the engine runs rough as guts, the brakes need a looking at, the wheel bearings are shot, and the seat looks like its been the victim of a bad repair job or two.. so all in all its like new! lol
 

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Made a bit of progress last fortnite, got the front fairing off and the indicators, aswell as started working out where everything runs
 

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Got a bit more down last week, dismantling it as best i can.. got stuck fighting with the handlebars and a few other bits for a while before giving up on progress for the day (since resolved, thanks bikeboy!!)
 

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Hooked into it over the weekend got the battery out and carbs along with many other bits and bobs. Have since made more progress but no photos yet - here's the latest
 

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So remember how I said it was running pretty rough?

I think I MIGHT have found a POSSIBLE cause.. You know im not really sure, never been good with all this mechanical stuff :p
 

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'Tis mearly a scratch... who needs chokes these days :)
Nice bike, they were the "Top Dog" back in their day.
That vacuum diaphram to the right of your index finder is the real POS. It's a safety fuel cut off for when the engine is not running. In otherwords no fuel flows until you build enough vacuum when cranking it to start it. So prone to headaches it's nicknamed the "Spawn of Satan" or SOS for short. By-pass it and throw it in the dustbin.
 
That vacuum diaphram is a Honda safety thing from the early '80s, like the vacuum petcock on the Suzukis from the same period. A new rack of CR's won't have it. But like Swivel said, unless you do other performamce upgrades, I doubt you would see the benefit from them.
I get optical-colonitis when it comes to spending that much... I can't see my ass doin it.
 
If you haven't heard from enough people how badly the vacuum petcocks suck, consider this; I was trying to get a Nighthawk with a dodgy charging system home with a serious summer thunderstorm chasing me. As I was zipping along keeping the revs over 3k to keep enough power going to the coils, the vacuum line popped off the petcock, and the bike stalled out. I was stuck by the side of the road (across from a church on Sunday morning no less!) without enough power to spin the motor over and with empty carb float bowls due to the petcock shutting off the fuel. I must have ran a quarter of a mile to get that bike push started and still got soaked. Screw those "safety" features.

Also, awesome bike! I am totally on board for this one. I found a set of choke plates and shafts on ebay for $20 that I think fit your carb; don't know if you need anything more to get the carbs working.

http://www.ebay.com/itm/HONDA-CB900-CB-900-CARB-CARBURETOR-BODY-VB43-CHOKE-LINKAGE-RETURN-SPRING-/370677383613?pt=Motorcycles_Parts_Accessories&hash=item564e1801bd&vxp=mtr
 
I don't like the original carbs on these bikes. To run properly they need to have the stock airfilter and the ugly air filter box. I put Mikuni smooth bores on mine (with other mods) and not only was the bike a lot faster but it started much easier on colder mornings. I think that 33mm carbs with pods and a free flowing exhaust might work but you won't get all the potential of them without head work, cam, big bore etc.
 
Here's where she's at right now.

Pretty much all to come out is the engine and box, and front and rear wheels and suspension (with tree etc.) so almost all apart.

Ive got a mate to be over on friday to give a hand with the engine - and then work starts on fixing her up!!

Re: CR31- the carb is going on for Blue Slip (safety check here in NSW, Australia) and registration, which the local mechanic is fine with. Once it's registered, a performance exhaust and probably hot cam will be going in, so it will be beneficial :)
 

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Had a mate come over the other day and finished disassembly of the bike! :) below is the engine, and my mate 'dancing' with the frame
 

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Yeh I know hey man Ive been cleaning out the garage. I had to reclaim the workbench so I could get all the smaller components worked on before I start reassembly (liek rebuilding the carbs and brakes etc. etc.)
 
Got a delivery for some parts today, huzzah!

Just waiting on some oil seals and a filter and ill start the tear down and cleanup on the engine

Hoping I don't need new rings or any other engine internals beyond this!!
 

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Trying to locate some Torque ratchets to start the engine rebuild - can anyone recommend any? I am low on dosh so I can't get snap-on. does anyone know if the pittsburgh brand are reasonable?
 
If you want a ratcheting "click" type, Protos are a decent brand for fair price. Just because I am an old school auto mechanic. I have a couple Snap-on torque wrench, but the ratcheting one is 1/2" drive and range is from 30 - 250 ft/lbs WAY to big for bike engines. Then I have a Snap-on 1/4" drive dial type, 10-50 in/lbs WAY too small. Any good Snap-On guy will tell you they need to be sent out for calibration on a regular basis to remain accurate.
For my bike engines I went to the local Napa store and bought a 3/8 drive old fashioned Beam type. My instructors way back when taught me these are more accurate that a "click" type when used properly. Steady pull to the correct torque, no jerking. If it needs calibrating you simply bend the indicator arm until its pointer reads zero on the scale and it's good.
Precise as it flexes the main bean and not the indicator with the torque. If you screw up on a pull and run out of room, loosen it, move your socket one flat and try again. Lube the fasteners threads and the bottom of the washer... smooth and steady pull. It ain't rocket science and these have been around since the dawn of machines.

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