bsumpter

I have a YS 63 that has about 1/2 gallon of Wildcat 20/20 fuel through it. It was broken in per the YS instructions with a MA 12x6 prop, and the valves have been adjusted to .003 two times so far. The engine is mounted on an UltraStick 40 (stock mount), and does a fair job of hauling it around.

I've noticed at high revs when there is a load on the engine (vertical climbs, loops, etc), I can hear a "clatter" from the engine. It sounds like valve clatter, or pre-ignition. It only does this at high revs, and only when there is a load on the engine. This is confusing me, as I'm sure the valves are within spec and I've done everything as per the instructions and from info gained here on RCU.

Other than the disturbing noises, the engine runs like a top. It has an incredibly low idle that is the envy of my buddy who primarily flys Saito engines. I am not getting the performance out of the engine that everyone here says they are getting, but this could be where I don't have a lot of run time on it yet. I get about 10,400 from an APC 12x7 prop. From what I've been reading everyone else is in the 11,500 range with this prop.

Any ideas? Think I've gotten a bum engine? Am I just being impatient and need to allow more run time? And finally, is the clattering sound normal for a new YS 63?

All suggestions appreciated.

Thanks!

Brian

Dave Shadel

If it runs fine, don't worry about it, just run it and enjoy.
Drop back on the prop size and let it wind up a bit.

D MAN

My Feedback: (1)

The aluminum mount cracks on those planes right at the engine bolt hole. i saw a motor fly off one when it broke completly while flying. i replaced mine with a DB plastic mount. Turn the motor over slowly by hand if you here a poping noise the problem is one of the push rod hitting the push rod tube causing it to bind up making the lifter snap back in to it's position when the camlobe is at the heel position. look at the push rods and you wil see where it rubs on the tube causing it to wear.