RE: New Radical 621T .21 Off-Road Engine
I have an OPS, 2 RB Mods Novarossi's, 2 OS engines and 2 Collari's.
By far the easiest to tune has been the OPS. I bought it used and it has been pinched twice already . I put about 5 gallons throught it and pinched again. Now it has about another 4 gallons and is going strong. It has almost as much power as my nova P5 but is way smoother. I get incredible run times with it 2. It is my favorite motor.
The only people who criticize these motors are people who have not owned one.