Scooterotica

rebuilding a vespa 90 engine
change to a 4 speed box
going ok [if a little fiddly, i am used to working on lambretta engines]
but when the cases are together, the kickstart pinion is not being pushed far enough towards the clutch, so is clicking on first gear...
compared the original 3-speed cluster, measures up the same.
it seems like the quadrant either is not over far enough, or doesn't have enough metal on it to retain the pinion out of the way... if the kickstart shaft is pulled outwards it clears, but that will just move back in...
I could change the quadrant maybe? or weld a bit on the existing one ??
or have i missed a trick ?
the spring behind the pinion goes straight onto the bearing ? with the dished washer on top of that ??
edit ~ sorry ^ meant other way round, washer first - concave side towards the bearing ? - then the spring

solved!
it was the kickstart shaft...
it was bent which meant the quadrant wasn't pushing the pinion in enough.
the old 3-speed cluster was worn to suit, whereas the new 4-speed one was catching...

now all i can hope is that the rear hub fits with the 16mm nut on the axle...

byron wrote:solved!
i.

Glad we helped you get to the bottom of that problem mate

About to do some fettlin on a wee 90 myself, I am going to fit a kit to it and convert to 12v, will a pk electronic ignition fit on the original crank or is the diameter/taper different?

Your 90 has a 19/20 crank with small taper for flywheel. Most of pk ignitions are for 20/20 crank witk large taper for flywheel. The pk50s and pk125s have the small taper cranks and their ignitions are bolt on solutions for the v90. Also a et3 ignition will be a direct swap, even cable colours ahould match. Et3 is only 6volts.

The et3 and pks ignitions are rareish compared to the later ones from pkxl and pkxl2. So I´d go the route of replacing the crank for a 20/20 one.

Anyway if you are kitting it a stronger crank is the way to go, piaggio didnt strenghten the cranks for fun, lots of stories out there bout flywheels passing scoots cause of snapped cranks.