i am wondering if a os 25 fx will pull a 11x 3, i used a norvell revlite 25 and it overheats and stops after a minute of running, I dont have a cowl around it so cooling is not issue.
I appreciate any advise.
Thanks Hayk

Your .25 engine should be OK with an 11x3 prop. Someone on the tach forum got 12,500 rpm with a 10x4 on a Mag .25. Of course, it will get hot and stop if it is too lean . Put on a 10x4 or 9x6 and see if that will run ok. Use a tach to see how it revs. If you get less than 12,000 rpm it is probably too much load for your engine. If the 10x4 is too much try a 10x3 or or 9x4. These props are dirt cheap and take a few minutes to try, so give it a go. Make sure you have the engine rich enough before you proceed.

Sounds like it's way over-propped, you can kill your engine rapidly with overheating. Go back to the sizes listed by OS. Once the damage is done.....it doesn't heal on it's own.

the manual says you can use all the way to 10x5 so i tought it should swing a 11x3 it just might be to wide of a prop, i am gonna put it in a Tak which has a cowl that is 8 inches wide so i need long prop to get anything out of it.

Big props have more weight thus require more to swing them. Sounds like a 40 would be more in order?
Good Luck

I tested it today it it ran fine, i am putting it back on the plane we will see how it does.

this is what i have it in