taco eater :
Alexander from Union Grove, WI United States
Black springs worked great for my FA50 with 60cc big bore, MLM sidebleed pipe, and a milled suzuki A80 high compression head. The black springs put the stall speed right on the cusp of the MLM pipe, vastly improving acceleration.
Installation isn't too difficult and took a little over an hour. Pay close attention to how everything comes apart and save yourself some time by not accidentally pulling out the kick start shaft and gear assembly when pulling the case cover off.