It is impossible to completely balance a crankshaft. The unbalanced forces acting upon it also don't help.
Ryan
My post was mainly intended to keep newbies from trashing their engines by trying to duplicate other experimenters. The main gains to be had on a sport engine are on the sleeve and crank window. Keep the dremel away from the connecting rod.
FYI- most of the Italian built engines already have good porting. The cheaper sport engines are the ones who gain the most from port work.
But...to make things clear to those who browse this board, being as I am a third generation dragracer(our legacy began in the 1950's), I believe I know just a bit about porting and balancing an engine. And yes you CAN balance/rebalance a crankshaft. That's what the counterweights are on there for in the first place. However I don't recommend the home porter to attempt to do so.
And... we have been tuning RC nitro glow engines since the early 1980's.
My intent is not to come on here for arguments sake, but I'd be amiss if I didn't share some wisdom from years of engine tuning and building. Good useful information abounds on the net concerning this hobby and I'm just glad to be a part of it.
Everyone have a great weekend and be sure and introduce someone new to RC!