I have an 85/86 LT250R and I was thinking about raising the compression level since my buddie works at a machine shop so he can re-face my head edges for free. How many thousands can/should I remove from the metal surface where the gasket goes? Is there anything else that needs to be done when raising the compression level/ratio??

 

You need to check your squish first. It needs to be .050 +or- .04. Only surface head to repair defects. If squish needs to be reduced you might consider installing thinner base gaskets.

 

Is checking squish done with clay?

 

Solder usually.
If your head gasket is like a TRX250R, you can separate the gasket pieces and use the thinner pieces.
Ya know...More comp means more octane ($$).

 

Really? Drip melted solder into the cylinder??

No my gasket can not be separated unfortunately but I heard a home made paper base gasket would do the trick, but I figured I could get even more from shaving the head.

I thought octane only applies to larger automobile engines that can "knock" I was told these engines do not experience knocking so higher octane does nothing?

 

No..Not liquid solder.
You undwind some and stick it in the plug hole and turn the motor over. It'll squish the solder and you measure that.
I'd shave the head .010 to start with.

OK higher octane::: Your statement is with stock stuff (auto or atv). Once modified and compression is raised, you use higher octane (auto or atv).
Will a 2 stroke knock? Yes. What you are (or would be) hearing is detonation (improper timing of the fuel charge explosion). A car motor will ping and run crappy. A 2 stroke motor will just melt a big hole in the piston.
Compression dictates octane.

 

Ohhh the solder thing makes since I thought there was a lot more space when being compressed then that!

Thanks for the octane information, so should I run it on my stock 2-stroke engine or would that be a waste of money? Would it help my piston run cooler?

 

Sorry about that should of been a little clearer. You need to remove the head and put a piece of solder across the top of piston edge to edge when it is near TDC. Then reinstall head and gasket and torque down head and carefully rotate motor slightly to compress the solder make sure piston stays near TDC so solder doesnt fall into a port. Remove head and measure the ends of the solder that will tell you your squish.

 

Modeling clay can also be used in this same manor to measure the space.