Look at Furry on the inside's posts about this, he taped up the case bore to catch the fillings and drilled the crank holes radially rather than take the case apart, this and a good flush after should work fine for a low percentage factor balance.
so can I drill from the top and I don't have to drill from the side is there a difference?
Im afraid that if you do not know this much, do not attempt to do this without someone more knowledgeable to help you out with the necessary mechanical and physics know how to accomplish this...I would hate to see you turn your motor into a rowboat anchor...DAMIEN
I was wondering about that, I guess you have to know how much the steel from the crank weighs by volume. The trick would be getting the holes in the right place.
Thats the guy. Thank you good sir.
No real difference in final results except that you won't know what the actual balance factor is, but if you drill 14mm dia and 14mm deep between the two factory holes on each side that should have it close to a 20% factor.
The first two holes are always at tdc and we know from repeated use of the process roughly what the factor percentage would be by the dia and depth of the holes. Notching can be done but it has adverse effects, first is that it adds case volume and lowers the cranking pressure (not wanted) next is it creates turbulence in the case as the webs push the charge around. When left full circle and case volume is an issue the holes can be filled with micro balloons and caped with devcon without adding much weight back, and this weight could be accounted for in the process.
