[Crunch]

I have an OS Max SX 60 from a TSX mystar Heli. The Heli has been in storage for about 4 years.

This last weekend, I tried to get the engine running, but I noticed there is almost no compression (!). The engine ran perfectly the last time it was run and has never been abused. Well, other than letting it sit for 4 years . .

I'm guessing that because this engine has a piston ring, the ring may have become stuck and is not expanding properly to seal the combustion chamber. But . .. this is a guess.

Any suggestions folks?

PS - Tried to take apart the motor, but I can't figure out how to remove the piston (???)

[Cougar429]

That would be my first guess. What you can try is pull the plug, drop in some alcohol with a bit of oil and reinstall it. Let it sit for a bit and check it again. Worst case would be to pull it apart, but rings are brittle and you may break it getting it out of the groove.

One thing to note is that if the ring is stuck, there is a good chance the bearings are also varnished and it would be a good idea to soak the entire engine in alcohol. If you try to spin the bearings too vigorously with all that crud in there it can do some damage.

Hopefully letting it sit that way, (with fuel/oil residue) has not caused internal corrosion. That's one of the reasons I block off the carb inlet and exhaust to minimize oil leakage and oxygen/moisture.

[chuebner]

Yes, it sounds like a stuck ring. Pull the plug, back plate and carb and just soak it for a while in some glow fuel. Should loosen the ring and free up any other gummed up parts as well.

Cheers
Curt

[tskca]

In order to remove the piston, you'll have to remove the sleeve first. Hopefully it isn't seized. This will allow room to move the piston around and the rod back and off the crankshaft. Note the orientation of the piston and rod relative to the front or back of the engine. Be careful not the break the piston ring. But if you do; see me :=) Ken (near the 2010 Olympic city)

[Crunch]

Thanks for all the good advise folks. I'll try your suggestions this eve once I'm done work.



Peter (crunch - the sound of the first and last flight of my old Kalt Heli)

[ByronF]

I agree with Curtis soak it in glow fuel. Take out the plug remove the carb and let it sit in the fuel for a bit. All synthetic would be better for this degumming than castor fuel.