Modern Vespa

The proverbial rabbit hole continues...

Below are pictures of the crank, piston, jug and head from the scooter I recently purchased. It looks like it has had a lot of issues including an overheating cycle that caused some pad scratches.

Also below are pictures of another setup from a motor that I did not use (With a Mazo crank). It looks to be in better condition that the setup from the original. But the piston shows signs of slap.

The first pictures are of the old setup followed by the new setup.

Question is should I use the second setup? Can I mix parts? What should I do?

Check if your scratched crank is true. Being out of true and bearing failure could both cause scoring like that.

You can mix and match the parts but keep the piston and cylinder as a pair. I'd be more worries about the condition of your sealing pad.

I agree about the rotary pad being the biggest concern. The unscuffed crank is probably the most promising. The scuffed crank might be ok and could be cleaned up, but may be out of true. One p and c looks to be in better condition and probably be fine with new rings and a hone. Check ring gap. Neither shows particularly bad damage.

There is nothing I can do about the pad. The scoring is not finger nail catching. There are no deep gouges. JB weld will have nothing to adhere to. I will check the gap between the pad and the crank once it is all back together but I cannot fix it. Worst thing is I get some blow by and lose some compression. This is not a daily and may do 500 miles a year.

After I posted I realized the old crank is from a PX. It is missing the sleeve on the fly side bearing. Are the cranks different?

How do you check if the crank is true without buying some sort of testing rig??

Thanks for the help.

Sounds like your rotary pad is fine. Depending on how far you want to take it, you could make some V blocks out of wood and check it with a cheap dial indicator. Or just eyeball it. Check for smooth rotation as you assemble the case. Use your best crank. You could just go over your cylinder walls with some sandpaper, check the ring gap, etc. Replace your rings if you like. I've run worse and it didn't seem to make a damn bit of difference to how it went down the road.