Hi Dave,

We have a .53 which runs fine on the ground, however after a few minutes in the air it starts surging/pulsing at high throttle.
Using 15% Omega and 12x4 prop. Engine is not lean. Took out the regulator and checked that there is no debris in the holes etc. Tank and check valve are holding pressure. I suspect it is some kind of fuel delivery problem.

Will the regulator from a .63 work in the .53 ?
Considering swapping them to identify where the problem is.

The problem is likely related to an air leak in the crankcase after the engine heats up in the air.

The 53 and 63 regulators are the same, but that is not your problem.

Ok, will take it down and check the gaskets etc.

Are full gasket sets available for this engine ?

thanks,

L

Gasket sets from YS Service. 775-782-4562

Also try Central Hobbies 800-723-5937

Out of curiosity, does the .53 have the gas port holes/slots in the piston ?
Could this engine benefit from this mod ?

It may or may not, depending on whether we ever serviced it. They were not done at the factory on 53's.

It is a good mod.