Well since you havent had it bored before i would just take the cylinder to the shop or just look at it and make sure it is not badly damaged and get it ported, bored and buy a new piston if you just want to increase power. Porting is a way better bang for your buck. As far as you burning a hole in your piston you are definately running lean, if you are running considerably lean on a 2 stroke it only takes a couple good hard runs through the gears before the piston gets excessively hot and starts to melt. You might have an air leak somewhere, most suspected areas are intake boots, carb caps and crank seal. If you suspect you might be running lean stop and check your spark plug, the electrode on your spark plug will usually start melting off before you severly damage your piston and cylinder. Ok if you installed the jet which you did and you dont hear an exhaust leak then its not bad enough to be an issue I dont think because if it was leaking where it comes out of the jug then you would hear it and there would be oil and sut where it is leaking. Since you took that carb off to put the jet in I would check to make sure the carb cap is on good, make sure you got the carb back in the boot good and the clamp tight, and make sure that your intake boot is not torn or dry rotted and cracked. Ummm thats all I can think of hope it helps.

 

well there were no leaks or anything i brought it in the yamaha dealer and the mechanic thinks the pipe was made and tested in california and the air down there is very different then here im at the right elevation but the air is very dry here\
anyway i was looking on project blaster and the guys from they say that the firebeather 240 kit is really good and the most reliable how reliable are these kits anyway?

 

If I got the firebreather kit i would need to run 108-110 octane race gas does anybody know where i could get this gas.