Hi,

I'm quite a new guy in the RC airplane universe. I got a student airplane with a OS 46-FX engine. It flown twice in the past and seems to be in great shape. When I turn the propeller, it stuck when the piston is at the top of the cylinder. Nuts of the cylinder head are evenly tight. I unmounted the engine to realize that the problem occurs only when the cylinder head is on and tight. Is it possible that the cylinder head gasket went tinner with the time and that the piston doesn't have enough space at the top to make a complete revolution freely?

I'm a french speaking Canadian... sorry for mistakes!

Thanks!

What's the French word for compression ?

NO... IT's not compression since even without the glow plug, the problem occurs.

Other idea?

When the head is off, does the piston top go above the block - even a very little bit?

It may be normal, Most engines of that type have a tapered bore,

there tight on top, but become straight when heated up during operation

NewC,

Well, with the head gasket, piston doesn'T seem to get above, but I must admit that it is really at the same level... difficult to say if it gets a bit above. But I can surely say that it gets flush with the head gasket.

Super Splatter:

The problem is, I can't get it started since the force at compression is too high for the prop to turn freely and make a full revolution. The piston is hitting the cylinder head.


Thanks guys! I appreciate you helping me!

The O.S. Max .46 FX is an non-ringed, ABN engine. That means it has a tapered cylinder liner. The fit of the piston will become tighter as it moves towards the top of the stroke. There is nothing wrong with your engine.

Here is our FAQ on the subject:

http://www.osengines.com/faq/product-faq.html#q1

Just use a chicken stick or an electric starter.

There is nothing wrong with your engine. It's supposed to be tight at the top. If it's not tight, then it's worn out. It will feel a bit loose after you land and the engine is hot. But as soon as it cools, the engine will be come tight at the top again.

Stop taking it apart. It's NOT broken. But, if you keep taking it apart, you're going to lose a screw or strip a thread on reassembly.

You ever heard the saying, "If it ain't broke--don't fix it." ?

Just go fly it and stop worrying. It's fine.

Ok oki!

I red on the subject! Thanks Bax...

Rcpilet! You're right! I knew that quote) I'll try it up tonight!

You guys are really nice ! Thanks for advice!

Yes my Friends! I got it started!

Quite funny for a new guy on RC ( I'm used starting real piper PA28 airplane with a single key )

Thanks for all you advice! PArticularly Bax!

Dear Buddy, your motor its an "ABC type", and this is perfect normal.
Good abc type motors have this squeaky fit at the top dead center, like you mention fisrtly,
Have nice flyings !!!

stg61abc..
Sorry wrong, this OS FX-46 are an "ABL" type " engine.

Jens Eirik