Modern Vespa

Just about finished the rebuild of the PX, with only a few jobs remaining, one of which being the ignition timing.

I've installed a Jasil 'Super' Crankshaft (Stroke 57mm / Conrod Length 105mm), with Jasil stating a timing setting of 123 deg, OR 6 deg after TDC. Never having done this before, is the method below correct, or have I missed something and gotten the wrong end of the stick?

1)
Find piston TDC (I can determine TDC using a calibrated depth gauge that screws into the plug socket), as I don't have a piston stop.

2)
Mark flywheel and channel to correspond with TDC as indicated.

3)
Mount a length of electrical wire at one of the flywheel cover studs, then loosely pop a timing disc onto the tapered shaft and set it to 0 deg where the wire and the 0 deg mark on the disc meet. Gently secure the timing disc on the shaft using the flywheel nut.

4)
Rotate the flywheel clockwise/past TDC to the point where the wire and 6 deg mark on the timing disc correspond, then mark the flywheel and channel accordingly.

5)
Remove wire and disc, secure flywheel, start engine and view timing marks on flywheel and channel using a strobe.

6)
If marks appear out of line, advance/retard ignition as required via stator plate and repeat the strobe/measuring process until both of the marks align at the 6 deg after TDC point

Sound OK, or have I gotten it all very wrong?

Thanks again, in advance (excuse the pun!).

Assuming your timing was at the IT mark (18 degrees BTDC), I would leave it at that. The change of crank should not make a difference, but sometimes aftermarket cranks will put the timing marks in a different place. Best to use a timing gun to be sure.

The 123/6 info refers to the inlet timing, not the ignition timing.

Ahhh, thanks again SWA45.

I'll run with your suggestion, but use a timing gun for accuracy. Does my method (for checking the timing), make sense... obviously now working to the 18 deg figure?

Step 4 is wrong.

Mark TDC on the flywheel and case, then rotate the flywheel counter-clockwise 18 degrees and mark that on the case only. That's where the spark should fire.

The only mark you need on the flywheel is TDC.

Thanks SoCalGuy... very helpful.

Really appreciate the guidance.

Happy to help