I just received a brand new OS FSa-110 engine and I noticed a small hole in the front of the engine exactly above the camshaft room. Does anybody know what is this hole for?

If it is a crankcase pressure breather (because of the pistons movement) how it may not expel oil?

I put a small piece of metal stick inside and I felt that something soft and elastice is there.

Thanks

Stelios

Thats normal, the new OS 4 stroke models no longer eject oil

Can you explain that? Is ther some sort of rubber diaphram in there? Just curious.

Bill

Yes please. Can anybody explain how is it possible to breath the crankcase from that hole but not expel oil?

Exploded view in the manual does show anything like diaphragm or anything else.

Stelios

The crankcase in vented into the intake manifold and the engine re-uses the effluent from the crankcase just like your car does

I've always thought it funny how a single letter can make so much difference in the meaning of two words such as effluent and affluent.

Back on topic, however, I'd love try try out one of the new Alpha series engines, but the pocketbook just doesn't have the guts to do so.

I guess it could be both. Inside the crankcase and considering the lubrication/cooling qualities it is affluent. When it is coming out of your engine it is effluent.

Its actually to assist in removing the wrist pin when disassembling the engine.You put in a wire thru the hole to push the wrist pin out the other side.

Those old pre-surpass engines were like an act of congress to get and old wrist pin out.

We use an "easy out" to remove stubborn wrist pins on the engines that had the hole in the rear of the case. You had to remove the wrist pin from the piston/rod assembly first, to fully-disassemble the engine. Then you could slide out the piston and remove the rod from the crank.

I learned to use the hardened dry wall or deck screws to get the stubborn ones out. Even then you have to grip the screw with pliers and leverage the pin out.

That is one of the best feelings . . . . when you finally get the aggravating old wrist pin out and you can get on with the rest of the engine repair.

Some of you refer to this as the gudgeon pin

Hello; Yes togatoga nailed it, the squishyness is the teflon pad that keeps the wrist pin from gougeing a groove in the liner. I once bought a used engine from a hapless fellow flyer, he had left the teflon pad out and now couldn't get any compression. I had to buy a new head/barrel and a lot of other parts to get it running (Saito 45 mk11), I put the "S" cam in it and donated it to our club trainer. It flew for 8 years with no further attention after that, excluding crash damage.

Has anyone found an Inverted Pitts Smoke muffler that fits the O.S. FSa110?