Burman Clutch

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
FWIW I stripped down the clutch (Burman) on my Comet to try to resolve the mongrel intermittent sticking clutch- crashing gears issue I was plagued with.

Having removed all of the clutch components from the bike - that lock washer in the clutch centre is a Orwellian nightmare - I was able to inspect it with some care.

What I found was that the slots in the clutch drum had developed distinct "valleys" where the fingers of the friction plates bore on it. On the central drum, I found simmilar valleys in the splines that engage with the pressure plates. It is no wonder that these plates were reluctant to move or separate when I attempted to engage the clutch.

With a suitable fine tooth file I have removed the valleys - I guess what I really did was flatten the mountain peaks.

Reassembly of the clutch has been completed but road testing will be a week of so away as I am also working on the global warming oil consumption issue I have and as a consequence, I have the top end of the motor currently spread across my workshop.

Martyn
 

chankly bore

Well Known and Active Forum User
Non-VOC Member
Martyn, the valve guides with "O" rings are a good wheeze if you are prepared to go ALL THE WAY to lessen atmosphere lubrication!!!
 

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
"O" ring - more correctly "X" ring seals obtained from messrs Kemp are being fitted to the lower valve guides right now. Likewise the cast iron oil ring (omega piston) was consigned to god and is being replaced by a modern 3 piece ring that will retain its tension.

Concurrent with all this I am also installing the "improved" version of ET100 with the much smaller holes in it

Martyn
 

stumpy lord

Well Known and Active Forum User
Non-VOC Member
To reduce the risk of the valve picking up your new lower oil seals and damaging them when fitting the valves to your heads, turn up a tube that is the same external diameter as the lower part of the valve, and with a taper at the top. Fit the lightly oiled tube over the valve stem,and insert the valve into the lower valve guid. the taper on the tool will ease the valve past the seal without any risk of damage being caused to the oil seal, the remove the tube.
stumpy lord.
 

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
I'm getting very concerned about applying lubricants toshafts entering orifices – or is my mind really wandering as I dream of one dayowing a lathe – or even more erotic – a mill!

Martyn

 

Matty

Well Known and Active Forum User
VOC Member
Hi
I have found that an apparantly sticking clutch on a Comet can be caused by the movement being limited by the clutch adjustment on the gearbox being set so that the push rod is not able to be moved fully in. When this happens, the clutch seems to be able to be adjusted by the cable adjuster but I have found that the handlebar lever can not be quite pulled back fully to the handlebar, so the clutch does not fully disengage.

The answer is to take up more clutch adjustment on the gearbox and then slacken off the cable adjuster to get the correct amount of slack again.

Be careful if you do this that the clutch lever the cable fits into inside the gearbox does not foul onto the alloy gearbox filler and cause clutch slip !!

Matty
 

redbloke1956

Well Known and Active Forum User
Non-VOC Member
FWIW I stripped down the clutch (Burman) on my Comet to try to resolve the mongrel intermittent sticking clutch- crashing gears issue I was plagued with.

Having removed all of the clutch components from the bike - that lock washer in the clutch centre is a Orwellian nightmare - I was able to inspect it with some care.

What I found was that the slots in the clutch drum had developed distinct "valleys" where the fingers of the friction plates bore on it. On the central drum, I found simmilar valleys in the splines that engage with the pressure plates. It is no wonder that these plates were reluctant to move or separate when I attempted to engage the clutch.

With a suitable fine tooth file I have removed the valleys - I guess what I really did was flatten the mountain peaks.

Reassembly of the clutch has been completed but road testing will be a week of so away as I am also working on the global warming oil consumption issue I have and as a consequence, I have the top end of the motor currently spread across my workshop.

Martyn
Hi Martyn, as you probably already know the clutch centre nut on a Burman Box, no matter what breed of bike, is renowned for coming undone...even with the lockwasher in place.
I drilled and tapped a small hole about 10mm out from the edge of the nut (into the Clutch centre hub) inserted a small bolt and tacked it in place so it wouldn't come out.
The bolt was cross drilled across the head before fitment and so was the Clutch Centre Nut, I can now safety lockwire the nut and be certain it will not come undone.

Regards
Kevin
 

Matty

Well Known and Active Forum User
VOC Member
Hi All

A couple of years ago I had occasion to take the clutch apart on my Comet and found that the clutch centre had been "working" on the splined gearbox mainshaft. The was because the centre nut had worked a little loose the splines at the centre of the clutch centre were now worn down to less than half their size, so I had to replace the centre for about £100.

The gearbox shaft was fine, but I feel that the arrangement is far from sound mechanically and unless one is lucky, is bound to work looe in time - all I was able to do was to hammer up the centre nut very tightly onto the TAB washer and hope.

Have looked at it a short while ago when rebuilding the gearbox and it still seems to be OK.

Matty
 
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