The K&B 61 is really nice old motor. Ball bearing. Different carbs over the years. Just remember that it's not a Schuerle screamer. Run it at a nice slow pace, not over 10-11,000 rpm. Be sure to run some castor oil in the fuel, maybe Sig 50/50 syn/castor, 5-10% nitro. Parts aren't too hard to find-they made a lot of them.