Third gear CP box

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bazajay
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Posts: 29
Joined: Wed Dec 04, 2013 7:42 am
Location: SWITZERLAND

Third gear CP box

Post by bazajay »

Hello All
I have a problem with my CP box, gears select fine but when driving in third it is very noisy and after a few hundred yards just drops out. I have rebuilt it, new bearings bushes and everything seemed fine. All the other gears are fine.
Before I take it apart (and can I take the clusters out without dismantling the clutch etc?) is there anything I should be looking for? The selector forks also seemed ok.
Any tips would be appreciated!
Thanks all, stay safe and virus free!!
Zen and the Art of Motorcycle Maintenance -Logic is like a bulldozer, it is slow but it will get you through any problem!
oldandsmelly
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Posts: 114
Joined: Tue Aug 30, 2011 4:35 pm
Location: DEVON UK

Re: Third gear CP box

Post by oldandsmelly »

Hi

I'm assuming the selector spring rocker is aligned correctly with the '0' mark lined up; it probably is OK as you've only a problem with third gear. My money would be on the mainshaft third gear having bad wear. I've stripped a few CP boxes and it's this gear that seems to often suffer the most wear to the internal dogs that engage the mainshaft sliding gear. These internal dogs can wear to be little more than raised bumps which when combined with their tendency to wear to points at the engaging end leads to the sliding gear being pushed out of engagement under load.

I always been lucky enough to work on gearboxes off the bike, but you should be able to remove the inner cover in situ and examine the third gear which is the outer one on the mainshaft.
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