Modern Vespa

Greeting all!

Got new points and a condenser and am trying to set the timing according to videos like below

However, according to reference material, I have found the correct placement is 28º. In most videos, the rotations are discussed in terms of Before Top Dead Center (BTDC), and one would rotate the flywheel in a specific direction to achieve that adjustment.

If I do that however the flywheel goes the wrong direction and the adjustment prts (holes) in the flywheel are nowhere near where they should be. Again, as I understand it, I rotated to 28º AFDC (After). At this rotation, the ports align, I am able to adjust, and the gap is set at about .46mm (the closest my feeler gauge gets).

She starts up and runs, seems pretty consistent, but still off by about 10-15º from my reckoning. At this point I simply should rotate the stator plate counter clockwise, correct?

My Vespa's Timing under a strobe:
https://rumble.com/v3ir21w-timing-issues-on-vintage-vespa.html

Setting Timing:

So if your marks are correct, you would need to rotate your stator counter clockwise for the marks to match. If the timing windows of the flywheel dont match, I'd wonder if thats the correctly flywheel or stator.

If you pull the spark plug, stick a screwdriver into the spark plug hole and rotate the piston to TDC, the screwdriver should be sticking up as far as it can. Then if you rotate counter clockwise, you should see the screwdriver fall down and your marks should be close. The screwdriver doesnt lie. If your marks arent close, your math is off.

If your math and marks are correct, and you cant move the stator any further counter clockwise/ flywheel window off, then I'd say its the wrong combo of parts and you'll need to modify them or replace them. Report back

Last edited by MJRally on Mon, 18 Sep 2023 16:25:58 +0000; edited 1 time

If his profile reflects the bike he's working on, it's a motovespa and they have that oddball stator setup. It could very well be a mismatch of parts.

I used a piston stop and a degree wheel. Should be accurate to within 2º... ish.

The stator was replaced using the marks placed prior to changing points and condenser, they look like factory marks. At any rate, there is some rotation available in the stater for sure. I can try that. Thanks!

Short answer: Yes, if that mark on your crankcase is 28° BTDC, it's firing too late. Stator needs to be rotated counterclockwise.

Don't worry where the "inspection hole" is relative to TDC. The important thing is to get the gap set correctly.

0.46mm is at the far end of the adjustment. The gap should be 0.30mm to 0.50mm. Get a smaller feeler gauge and you should be good to go.

Had to go through the process twice, but finally nailed it!

https://rumble.com/v3lusdh-vespa-timing-nailed-it.html