OK so I opened the breather orifice up to 3/16" but the box still leaks like a drunken sailor with a prostrate problem.
M
Burman Gearbox Leak
- Thread starter Martyn Goodwin
- Start date
OK so I opened the breather orifice up to 3/16" but the box still leaks like a drunken sailor with a prostrate problem.
M
Hi Martyn, I have had experience with 3 Burmans , each of which were totally torn down, new bearings was all that was needed. With the first gear boxes, it was stressed by advisors that a mixture of grease and oil was needed, so that is what was done. Custom mixed grease and oil were stirred up and sloppily inserted. This seems to work well but leaked out the kick start , shift levers, even cover studs /nuts. Cleaning was required every time you rode 100 miles. So finally, on the last Burman, my own, I had the outer case bored to receive a lip seal at the kick starter. An easy job for a machinist and the machinist ordered the seal from a local source. Back together this Buman did not leak at the kick start, still using a vintage Vincent mix, but the shift shafts still weeped as usual. So I lamented about not oringing the shift shafts. I had shift problems, so this Burman came apart several times for parts replacement, this time I filled with engine oil, so the Burman still weeped, even when at rest.
Recently the Comet Burman outer case gasket was pulled to the interior with a kick start stop rubber wiping the inside of the cases and pulling it in , major leak! Regasketed the outer cover, installed new bump rubber, squeezed in some Castrol 000 grease and the leaks have gone away! I cant believe it!
To insert the Castrol 000 grease, first the grease is ladled into a quart plastic bag, cut corner off bag and squeeze the grease into the Burman fill port, like using a cake decorator.
Cheers
Craig
PS I think the clutch cable hole allows enough breathing for a Burman
Recently the Comet Burman outer case gasket was pulled to the interior with a kick start stop rubber wiping the inside of the cases and pulling it in , major leak! Regasketed the outer cover, installed new bump rubber, squeezed in some Castrol 000 grease and the leaks have gone away! I cant believe it!
To insert the Castrol 000 grease, first the grease is ladled into a quart plastic bag, cut corner off bag and squeeze the grease into the Burman fill port, like using a cake decorator.
Cheers
Craig
PS I think the clutch cable hole allows enough breathing for a Burman
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Can someone kindly explain how a gearbox of this design gets "pressurized"?
Blowed if I know! There is a substantial "hole" where the clutch cable enters the gearbox, plus in my case a 1/8" hole thru the center of the inspection cap.
BUT
Despite all my efforts with felt washers and o rings a small quantity of grease still seeps out from around the outside of the gear change shaft. No enough to require a gearbox top up, but sufficient to stain the exhaust!
I figure the next step will be to remove the gearbox cover and try to get some form of seal onto the inside, but it will be a very messy job. I am wondering if there should be a felt seal in that location, around the gear change shaft, squashed between the spring box and the outer cover - any ideas??
Just noticed I have the perfect excuse to strip the Burman box to fix the grease ozze from the gearchange shaft. After a run today I noticed a new oil stain towards the back of the bike - crawling around on the floor I discovered a slight weep from the gearbox gasket - the one between the main gearbox body and the inner cover. Bugger. Have a run scheduled this weekend and insufficient time before then to fix it. Will still be on the run, but a gearbox "fix" will be on the books starting late next week.
At least these bikes stop us from becoming bored!!
Martyn
At least these bikes stop us from becoming bored!!
Martyn
What the heck - in the morning I am going to drain the fluids then lay the bike on its side and get stuck into replacing the offending gasket in the gearbox. I always new the crash bars would come in handy 
M
M
Two of my C Comet Burman boxes had leather collars/seals fitted snugly over the projecting gearchange bush on the outer cover which are then squashed slightly by the gear pedal when fitted. I don't know how effective they are but I have left them in situ. Both boxes have had internal oil seals fitted to the kick start and gearchange shafts. I don't know how this was done as I have never opened up the boxes to see. However if one uses oil only it leaks from the clutch adjuster cover. It is difficult to see how this could be sealed satisfactorily. I reckon trying to make a Burman gearbox oil tight is like trying to stop oil drips on Stephenson's Rocket.
Take the cover off, remove the block, then you can fit a couple of O-rings there to cure your problems.