Cota 349 weird clutch (gearbox?) issue

[turbofurball]

So, my White Wonder is experiencing an odd clutch issue following an engine rebuild (done by someone very experienced, it had new seals and mains, the clutch and gearbox looked fine so just went back in as-is).

 

When cold everything works as expected, but when it's thoroughly warmed up there's a clunk or two as you pull away.  It happens in any gear, and you can hear it as well as feel it through the frame - it's like something isn't quite engaging until the wheels are in motion, or as if the chain had excessive slack.  Once moving it feels fine both on and off the throttle.

Does anyone have any ideas?  I hope we don't have to split the engine again

[feetupfun]

Next time when you put it into 1st gear from neutral with the motor running, while your foot is still holding the shifter down, let the clutch out a little bit and you will probably find that the shift lever drops a little bit further (and there is a clunk). That is signalling that it is fully engaged in that gear.

The clunk you have described with your 349 is the bike finally going fully into gear and is a fairly normal thing with 348 and 349 Cotas. If you can select all the gears and it stays in a gear once fully in gear, your mechanic has done a great job.

 

[turbofurball]

Thanks, I'm relieved that I'm not shredding the gearbox!

It's odd that it wasn't doing this before, but I'll give that a go next time it's out (currently having ignition issues ...)

[section swept]

Some things to check, even the best of us make mistakes. Is the gearbox output sprocket secure? Engine dead and in any gear push the bike back and forth, does it make a similar clunk? If your bike didn’t do it before the strip then why is it doing it now? I know you want answers but that’s the question you need to be asking your mechanic. Hope it’s an easy remeady?

[turbofurball]

Those are smart questions, I'll give it a push next time I've got it up to operating temperature (it's tight as a nut when cold)

As for what's changed, when the engine wasn't running it would drop into first gear while being pushed, IIRC the spring pressure for the shifter cam thingy was upped a little bit so it didn't do that

[samwisemcg]

On 9/11/2018 at 11:00 AM, turbofurball said:

So, my White Wonder is experiencing an odd clutch issue following an engine rebuild (done by someone very experienced, it had new seals and mains, the clutch and gearbox looked fine so just went back in as-is).

 

When cold everything works as expected, but when it's thoroughly warmed up there's a clunk or two as you pull away.  It happens in any gear, and you can hear it as well as feel it through the frame - it's like something isn't quite engaging until the wheels are in motion, or as if the chain had excessive slack.  Once moving it feels fine both on and off the throttle.

Does anyone have any ideas?  I hope we don't have to split the engine again

Turbofurball, when you had your engine rebuilt, was it done by a friend or by a professional you didn't know?

The reason I ask is I have a 348 that could do with an engine rebuild and I don't know anyone in the south who will work on a Montesa.  

Thanks,
Sam

[turbofurball]

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