Modern Vespa

hello, recently purchased a bike. hooked up a new battery and it was struggling to crank.

sounded like a starter on its way out. purchased a new starter and installed but i am having the same issue with the new starter.

when it cranks, it struggles on 1 part of a stroke...

im assuming compression. but as soon as it gets to tdc it seems to losen up until it returns to what i am assuming is the compression stroke where it will struggle again.

anyone have any ideas what my issue could be?

i have been unable to crack the 19mm bolt that holds my variator cover in place so i can't turn the engine from there.

with spark plug removed, the engine spins freely when cranking.

How many miles on the scooter? I am wondering if a valve is tight? Have you checked them?

On the 19mm nut, have you tried an impact wrench?

That will be a valve clearance issue without doubt. Almost certainly the exhaust valve is far too loose a clearance, so the valve hardly opens which makes it very hard to turn over. Even the start-up decompression gizmo doesn't help. Just had one of these to fix. I reckon whoever set the clearances before had unwittingly had another feeler gauge stuck to the back of the 0.15mm one - easily done if you don't check for it!

what should stock valve clearance be?

i will have to get myself a gauge and try that.

the bike has 30k on the odometer.

and just sticking with the problem solving. say valves were good.

what else could cause these symptoms?

i would like to get to work on it tomorrow armed with a list of stuff to try until i hopefully find the issue.

went ahead and ordered myself a gauge... should be with me in a few days.

also, it seems that valves should be .10 intake, and .15 exhaust.

That seem right for the X8 - later models have slightly different numbers.

so after spending some time today fiddling with my valves, my issue still persists

managed to get my variator cover off so i can spin the engine over manually now.

anyone have any ideas?

TIA

Luke

Hi I'm having the same issue, do you get it sorted, if so what was at fault?

Cheers