piston hitting head

Peugeot 103. Just threw on a 70cc cast-iron polini kit, vintage italian import (thanks kirk for the deal), and I bolted on my mildly decked stock 50cc head and the piston seems to be hitting the head and not turning over. I didn't have this problem with the other one. I even threw two aluminum gaskets on, to no avail.

I'm cutting several more gaskets now to raise it a bit more. Does anyone have experience with 70cc pistons interfering with a decked 50cc head?

fyi- I tried putting a 50cc high comp head on my stock 50cc cylinder once, and the piston hit that too.... is it possible I've got some other problem?

thanks!

Re: piston hitting head

It's hitting the outer ridge where the diameter of the 50 is smaller.

You'll have to cut it out, or get a 70 head.

Re: piston hitting head

Sabat, that was the 'DUH' in this situation. and the further 'duh' was that my gaskets were also 50cc diameter. I cut four new gaskets and used those, it doesn't hit anymore....

with all four aluminum can gaskets the compression is ~130psi cold, the port work on this kit is very mild, so I'm anticipating I won't need more compression to sustain decent low end.... we'll see.

Re: piston hitting head

sabatino and sabat are two different people.

Re: piston hitting head

if you are cutting new gaskets, cut them to the size of the cylinder, not the head. if you cut it with the size of the head, the piston will hit the gasket.

Re: piston hitting head

lol

I did the same thing first time around with my old Airsal--Talk about confused.

Re: piston hitting head

make your own squish like i did.

Re: piston hitting head

Nice work for a done by hand w/o a machine.

Re: piston hitting head

thanks. trace, dremel, sand, polish, mill head to tolerance, done. 1-2 hours of work.

tested with crushed solder for tolerance, within bell's ideal specs. stoked.

Re: piston hitting head

Peter rockin a beard... I like it.

Re: piston hitting head

dude its rare for me not to have a beard! its long right now though. winter.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account