piston hitting head

Andy /

Feb 10, 2009 10:23PM

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

Eric Sabatino /

Go to branch

erics

Feb 10, 2009 10:45PM

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

Andy /

akpasta OP

Feb 11, 2009 01:20AM

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

leee /

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zach

Feb 11, 2009 03:05AM

sabatino and sabat are two different people.

Re: piston hitting head

Grande Deluxe /

dccracing

Feb 11, 2009 10:26AM

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.