Author Topic: Vincent Comet Gearbox Issue  (Read 6160 times)

Offline VintageBike

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Vincent Comet Gearbox Issue
« on: July 13, 2016, 09:59:54 PM »
Hope someone here can help me...

I have a Vincent Comet (with Burman gearbox).  All has been fine until....

1. A lot of slack suddenly appeared at the clutch lever (within a 1 mile journey).  Someone else was riding the bike at the time.  I adjusted the slack out by removing the small cover on the gearbox and adjusting the nut on the actuating lever fulcrum.  Clutch then seemed OK.  Not sure what brought this on, or whether it is relevant to the next issue....
 
2.Immediately after the clutch issue, when sitting with the engine running and  in neutral, I could here the sound of gears occasionally just catching each other, like the sound that you sometimes  get when in a false neutral.  Otherwise gears were fully functional and OK to ride home.  Further examination has confused the hell out of me.  With the bike on the rear stand, all gears (and neutral) can be selected.  However, as soon as the bike is taken off the stand and I sit on the saddle, the bike falls out of neutral.  It is then very hit and miss as to whether neutral can be selected.  As soon as the bike is back on the stand, or I dismount, then neutral is possible.

Has anyone any idea what I should be looking for when I strip down?

Thanks

Nigel

Offline chaterlea25

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Re: Vincent Comet Gearbox Issue
« Reply #1 on: July 13, 2016, 10:57:10 PM »
Hi Nigel,
It sounds as though the nut on the end of the gearbox mainshaft that holds the kickstart ratchet in place has come loose, allowing the mainshaft to drift towards the clutch
It should all become apparent when you remove the gearbox righthand cover

John

Offline VintageBike

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Re: Vincent Comet Gearbox Issue
« Reply #2 on: July 14, 2016, 05:52:21 AM »
Thanks for the reply John.  I'll update with my findings.  Thanks for taking the time to reply.

Cheers
Nigel

Offline chris mac

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Re: Vincent Comet Gearbox Issue
« Reply #3 on: July 18, 2016, 12:51:24 AM »
Nigel,  I'd also be checking the nuts holding the gearbox and mounting plates
Best,   Chris Mac

Offline VintageBike

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Re: Vincent Comet Gearbox Issue
« Reply #4 on: September 15, 2016, 07:06:15 AM »
Sorry for slow update.  John, you were spot on.  The mainshaft nut behind the kickstart cover was loose.  Tightened this up and (after many hours of trying to get the cove back on with the gears correctly synched!) all seems OK.

Thanks for your advice.

N

Offline chaterlea25

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Re: Vincent Comet Gearbox Issue
« Reply #5 on: September 15, 2016, 08:56:46 PM »
Hi Nigel,
Thanks for the feedback and glad you got it sorted   ;D

John


Offline VintageBike

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Re: Vincent Comet Gearbox Issue
« Reply #6 on: September 16, 2016, 09:39:53 AM »
yep, although it has proved to be one step forward and two steps back.... Took the bike to the IoM for the Manx, and after the first day developed a very nasty whining from the gearbox under load.  The clutch centre splines are on the point of giving out totally, and the pushrod has worn an end toatlly.  So will be rebuilding all that before looking elsewhere..  Good time on the Island though!
N