new to this myself , i find it quite interesting , i built several race bikes in the 1980's , a saw motor is basically the same , except it looks like you pretty much have to make your own parts , it would be nice if you could buy a wiesco forged racing piston , i looked at the dirt bike pistons you might be able to find one the right mm's and then modify the skirt and the wrist pin to fit your crank and cylinder , port and polish the jug , bore it and install a steel sleeve or have it re-plated , lighten and polish the crank and rod , add a bigger carb and a modified muffler or a race bike pipe , well this is what i was thinking for myself , they also run a stock class , a few mods might make the old mac competitive , be careful though , i hear it's as addictive as crack ..