Vespa P2 jumping gear

[elvislives]

have just built a P2 engine and have done 200 miles on it trouble free then bang starts jumping out of gear in 2/3 when gouing through the rev range- brand new everything so cant understand why.

i have tryed a few other selector boxes with no joy.

any idears before i strip and look at the gears.....

[dDUBlya]

The old cruciform problem.
Replaced about half a dozen of these many moons ago. They never seem to stay good for long.

[elvislives]

The old cruciform problem.
Replaced about half a dozen of these many moons ago. They never seem to stay good for long.

it was brand new with the new build and it was geniun- never had one go that wuick before 200 mile in. :fb:

[tomdavid1988]

cables

[goldeneye]

cables too tight or snagging (the outer can melt where it goes past the exhaust down pipe and jam the inner) cruciform loose on selector rod, selector box pawl worn, gearbox shimming incorrect. ive got a young lad coming down next week to do his gearbox on his 1981 px125...he"s had 8 cruciforms in a year! something wrong there methinks!

[elvislives]

cables too tight or snagging (the outer can melt where it goes past the exhaust down pipe and jam the inner) cruciform loose on selector rod, selector box pawl worn, gearbox shimming incorrect. ive got a young lad coming down next week to do his gearbox on his 1981 px125...he"s had 8 cruciforms in a year! something wrong there methinks!

sussed it, inner face on the gears is a bit worn on 2nd and 3rd - but build the engine from scratch so would have made sure they were in good nick, they have done in the cruciform- so on the look out for a full set of p2 gears if you hear of any.


cheers :fb: