G: Gearbox (Single - Burman) Burman Gearbox advice needed.

nkt267

Well Known and Active Forum User
VOC Member
I think i would go for wiggling the box out through G50/1 as once the inner case is off the RFM looses it's support as does the engine. you are almost all the way to splitting the bike..good chance to practise your Anglo saxon if you go this route but it is not impossible..i've done it a few times now..
 

highbury731

Well Known and Active Forum User
VOC Member
The engine shocker will have to come
Off. I would use a chain wrench to stop the engine turning while undoing the nut.
I put the chain wrench around the body of the shocker.
If I have to remove the ESA nut, or otherwise lock the engine, I find a rope down the plug-hole works well. Just make sure the valves are closed, or you will not be happy....
Paul
 

Robert Watson

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VOC Member
I have had EXACTLY that problem, not once, but twice with my Comet. Gearbox drive sprockets had NOT been hardened.

Also can be caused by the drive sprocket nut not being securely tightened allowing it to move ever so slightly then 'worrying' away at the splines on the sprocket. Can even damage the splines on the gearbox output gear shaft.

The give away is that you can kick start the motor, you can change gears but nothing happens at the back wheel - its just like a broken drive chain - till you wake up that the drive chain is intact.
Or the rear drum breaks just on the step down from the from the rim to the hub, and neatly enough that the sprocket and drum look just fine. There you are well south of Perth in the Margaret river wine area and quite a few miles from anywhere and it's 11 in the morning and starting to get rather warm. Thinking the worst (this on a twin) about what has failed in the gearbox. with the rear mudguard flap up and on the rear stand you just happen to give the back tire a spin, and hesitate. Did that chain really not move. Do it again. Say Eureka out loud, assure the wife you will be mobile in 20 minutes, tell the guy that pulls up in the Mustang that you are good to go, Turn the back tire around having had the foresight to run the same size sprocket on both sides so no sprocket changing required, And shortly head off to Adelaide where a new rear sprocket will be waiting. Tell me on what other motorbike that is possible?
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Vincent's are great things to have. had the same in NZ at Christchurch, but I had assistance from Russle Byfield that I spent three days with him and the two guys that ran a bike shop, swapped the steel brake drums around as bolt holes were slotted. Alan bolts were fitted (into new holes) from inside to out as radius of steed pressed drums hexagon bolts didn't fit squarely enough, spring washer and nylocks and it just clears the brake torque arms. Harvey shipped the bikes home after he toured NZ in 2019 since then the rear wheel has been put on the "A" Comet and a new wheel built for the twin with WM4 x 21"!!? the same as the front with SPEET T.L.S.brakes.
 

timetraveller

Well Known and Active Forum User
VOC Member
Thanks guys but it is not the rear wheel, a brake drum or anything at that end. I checked all that. Jason is busy this weekend so next week we should find out what the problem is. Had a long talk to Clive Smith this evening who phoned me about another matter. He has a Comet as well as a twin so it was useful to exchange some ideas.
 
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