(sorry for necro posting, just alot of confusing jargon, came from Google search) why couldnt you just balance the entire crank assembly (crank, rod, piston) on a flat, level surface (like say two perfectly level levels), and drill until the crank stays in whatever position you set it in? essentially making the whole crank neutrally balanced. Maybe I didnt read the posts clearly enough but not only does it sound like I need equipment I dont have access to, but alot of stuff I didnt quite understand (placing weights in the rod journal??) I suppose what I'm asking is for a translation for noobs.
EDIT: thought about it a bit more and I realized... the piston is heavier the faster it goes, thats why you need to balance for specific RPM's... at 8000 RPM the piston and rod weigh roughly twice as much (I'm not about to go into peak speeds, I just quickly calculated average speed) as normal so that would throw the crank out of balance
EDIT2: So... I suppose I have to ask, seeing as how my noobiness is getting the better of me... how would I balance the crank for an average speed of 50kph (~30mph) on my 66cc? I have a 36T sprocket meaning I'd be running around 6k RPM