I am in the same boat that you are. I picked up a Giant Stinger from a buddy that had a US41 in it. I am replacing it with a Sachs 51cc conversion. It takes 1.5lbs of lead to balance on the money. I ended up replacing the aluminum standoffs on my engine with longer ones made of Brass. It added the needed weight while shifting the weight of the engine farther forward. I ended up adding about .75lbs instead of the origional 1.5lbs it took.