If 60cc kit increases comp 20% over the stock, is it bad idea to run hi-comp head?

I plan to go to a 60cc piston vs the stock 49cc. woul dit be a bad idea to run the hi-comp head with the bigger piston?

Re: If 60cc kit increases comp 20% over the stock, is it bad idea to run hi-comp head?

If you are putting on a whole new cylinder the port timing will likely be different than stock so a direct comparison of displacement to compression increase would be foiled. I have never seen a stock cylinder or any cylinder for that matter that couldn't survive a little more compression than the stock figure. Get a compression tester then you can dremel out the combustion area in the head (use the sanding roller drums) to suit your needs. People talk about squish on here a lot but to get the compression low enough I usually have to carve out about half of the squish area anyway so don't get too hung up on that. 140 psi is very safe. At 180 psi you better have some good tuning skills, this is with a big pipe. the higher the compression and the harder the pipe hits the more fine the jetting must be where at some point you wish you had jets in half sizes. But at that level you are probably going to blow up as you ride your bike into a pocket of cold air. Good luck and enjoy the learning process

Re: If 60cc kit increases comp 20% over the stock, is it bad idea to run hi-comp head?

oh yeah, it is for sure a process. i seized the motor on my FA, i followed the performance wiki. hi-comp head, cooler plug and 50:1. i am going to bore the stock cyl to 45mm and i am trying to figure out if i should ditch the hi-comp cyl head. i can compensate for the head milling by adding a spacer to the base, also there by exposing the ports by another 20% at bdc.

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