Re: PA50 jetting/performance questions

• Author: Jon (---.dhcp.nwtn.ct.charter.com)
• Verified User: therieldeal
• Date Posted: 05-14-08 07:05

the head was properly torqued, to 9 ft lbs.

i’ve been reusing the stock hobbit aluminum (?) head gasket, as it was in good shape. i had no compression leaks, but i definately had exhaust/air/fuel leaking out of that decompression hole (i could see/hear it). if you look at the picture of the spree head above, you can see how the sealing surface of the head isnt completely square… the decomp hole is left at least partially uncovered, creating the leak. the hobbit gasket does cover the hole completely, but the spree head does not clamp down over it.

when i get around to replacing that base gasket… am i going to need new rings and/or a cylinder hone to get things to seal properly when i reassemble? the cylinder walls appeared to be in excellent condition.. no scoring, and ports were not clogged at all.

as an aside, i must say that i’m having a lot of fun experimenting with this little two stroke. i have a fair bit of experience tuning high performance turbocharged/fuel injected 4 cylinders (in cars), and the simplicity of these mopeds makes things so much easier. you don’t get to do much trial and error sort of experimentation when you’re making 165hp per liter… things tend to blow up! nor can you swap the cylinder head three times within the course of a single afternoon to test various compression ratios :).