Bill, the Moki was used before on one of my grinders and I loved the way the engine ran. That motor never missed a beat. This grinder had about 675 square inches and wieghed 58 oz. The Moki 51 is as close to a four stroke as you can get. On a 2-4 break it would up the rpm about 300 rpm and the plane never wound up in the wind. It would do the pattern on 4 1/2 oz. of fuel and it ran great on synthetic fuel. I used Byrons fuel and added about 4 oz of caster to a gallon. I think the Bear presents itself as a bigger plane than it is. I am going to try and keep it under 58 oz. I also have a backup for this motor.