Originally Posted by EdwardN

Sure you can ask any quetions-this is why we came here in forum to learn, share etc.
Number 51% came from many years of trials and it is our numbers, it doesn't mean everybody use the same numbers. It is target number but not always can be easy reach.
BTW, try to make 100%-you won't be able to do that, regardless how much tungsten you will put there. It is doesn't metter how much you can lightening piston assembly-you can go just to reasonble limit where parts will be strong enough to don't brake under the load while motor is running 40+ K RPM. Ones you will make them srong enough they will have some weight.
One of the reason why in air models (there is space to do it) some people try and do carb on opposite side, but we don't have that luxery. Tehere is way to make better way to do balancing-use rear induction-you can locate induction position that it will help achive best balancing with minimum unbalanced rotating mass ( way lesss then we use front induction), but again it is depend of aplication-some place is possible, some not. Please see the pics of samples.
Balancing is whole hell of controversial ideas and theories and people stick with something they find work better for them.
BTW, look the pic of sleeve-it is art of work!!!!