Originally Posted by
grizz1
Run the new GX-7R or MG66 in your buggy and you won't look back. Just as powerful and probably smoother than what you have tried before - and much more affordable.
The later model (black case) motor will be a Gen 5.5. The 5.5 motors came out with a modified crank that had better balance and tolerances, plus a larger crank pin. Also comes with the newer 21-0600 Pro con rod to match the crank pin. Gen 5.5 carbs were also improved over previous models.
I need to correct myself here.
The Gen 5.5 (std) and GX Series (coated) cranks came out with a tolerance change only. No extra balance work.
The MG66 is the only motor with both the tolerance change and the balance work done on the coated crank, which explains why it rev's it's little head off and won't stop winding out
