[stegl]

I believe that a 4 stroke needs a higher pitch due to lower max rpm's vs, a 2 stroke as the 2 stroke develops it's max power at a much higher speed. That's another thing I like about Electrics as they develop gobs of torque at any rpm; not just a narrow band at the top end.

[mrrandyman]

I would just stick with the recommended engine for that plane. I like the Saito or OS engines myself.
They last many years if maintained properly.
Just stick to the basics until you've flown the plane to a point of where you want to upgrade to something else.
Trust me you will change your mind a hundred times in one season before deciding on your next project and that big engine you want to buy may not fit the bill for any of them.

[Ed Smith]

Surprised about the ASP having an issue but that could have been one of twenty thousand motors or more motors.

ASP stands for "All Sorts of Problems"

Stay with O.S.

Ed S

[williame3590]

Good one Ed.

Bill

[OLD PRAIRIE RED NECK]

Originally Posted by Nazair

Thanks for the suggestion. I looked at the Saito prop size page and no 5" pitch prop is recommended for the 91, would you have a suggestion?

True, the 14 x 6 is the lowest pitch they list. Normally if you go down one inch on pitch you need to go up one inch on diameter to keep the engine in the same RPM range. That would make it a 15 x 5 prop. I suspect ground clearance problems with that diameter and trike gear. You may get away with a 14 x 5 prop if you watch that the engine RPMs don't exceed the manufacturer's specs. A 3 blade prop may work in a smaller diameter but I think 6" pitch is the lowest I have seen.

I am running an APC 14 x 4 wide on an OS .90 4 stroke but it puts out much less power than a Saito.

[TomGSMackay]

You can't go wrong with a Saito 82 or 91 in a 60-size trainer. Not experienced with the ASP's, but OS and Saito have both been good to me.
Save the 120 for another airplane. In trainers, as in all airplanes, lighter planes simply fly better.