P2 running rough

[rosscla]

Won't hurt

[stonerosesmod]

Well it fired up after a cpl of kicks and revved clean with choke out.Put choke in and got the same dying effect when throttling off idle and had to turn tickover higher to keep it running.Sprayed soapy water over casings where I could but no bubbles.Turned off and drained gear oil,plenty in there but don't think there was any fuel in there.Might whip engine out and try and rig up a leak test with an old inner tube and spray soapy water over casings again and flywheel seal,barrel etc.Then might have to crack casings open again

[ducksta]

Drive side seal, had same myself

[stonerosesmod]

When I got the engine just before winter,I stripped and rebuilt it as it was an unknown runner.Was all good inside but I changed bearings and seals anyway.It smoked bad and I stripped it again to find the main seal had been nipped,possibly when I installed crank first time.So I opened engine again and fitted another metal one and made sure it was ok when I pulled crank back in with the tool.Just wondering if it is the seal again then why? I've rebuilt a few p range engines for mates which have ran ok so I've either been lucky or somethings up with mine! Doesn't smoke though so maybe an air leak test first then I'll open the b@5t@rd up again

[gaz_powell]

If it's had a few seals in and out -I would use a blue fully rubber coated corteco one with a smear of yamabond.

[mick1]

In Theory
If you get a cloth and block the exhaust when running it should die.....if it doesn't it points to one of the seals (flywheel/main) leaking......in theory

[stonerosesmod]

Update!
Finally got in the garage and stripped the engine.No visible cracks in the casings or damage.Some gear oil in the barrel and crankcase mouth.Removed the crank and main seal is intact,but the rubber is egg shaped in one area,plus it has rubbed on the rear of the metal seal on the bearing. I'm guessing as its the second metal seal I've fitted,the crank must be out of balance or worn out as I can't think of what else it might be?

[stonerosesmod]

Well looks like I've found the problem,turns out the main bearing is a performance one and the centre is slightly wider than a standard bearing and had been rubbing on the rear of the oil seal distorting it.Ordered a new standard 8 ball bearing and metal seal,will try again!

[rosscla]

I recently fitted a metal malossi seal an for some reason when fully home it was still catching the crank web when the crank was fully home, to the point the crank was locked up. I took it out and fitted a genuine Vespa one and it's fine.