Hey guys I need your help. I have a ST 61 that I took apart to clean. As I attempted to slide the piston back into the cylinder the piston ring expanded and now I cannot compress it to get the cylinder back in [:@]. HELP!!! Thanks

Look closely at the piston where the ring fits in....look for a small brass
pin that locates the ring where the gap goes. If the ring is not positioned
properly, it will not compress far enough to get the cylinder over it.

FBD.

If you look closely at the cylinder wall, you should be able to see a mark where
the ring gap was running up and down on the wall. That will help you find the
pin location. It is usually on the left side of the exhaust port in the front.

FBD.

Well I'm officially screwed! I got the ring to compress and as I "helped" it back into the cylinder the ring broke and now the piston is stuck at the bottom of the crank case. Is it possible to remove the sleeve? Man, this is pitiful[&o]

Bummer....take a piece of dowel rod, or wood....put it on top of the piston.
Lift the engine off the bench, holding it by the cylinder with your fingers....

....and give the dowel a whack. Knock the piston down and out of the cylinder.
You might get lucky, and only need a new ring. Do not dispair....learning this
engine stuff is not easy by yourself.

Dave.

FBD,
I've got good news and not so good news: Good news - I got teh piston out.

Bad news: The top of teh piston broke off in the process [:@]

Oh well, the plane is not finished yet anyway so now I can order the new parts.

Thanks for all your help.

*rcnats*

rcStan:

When you get your new parts be careful. Some of the ST pinned rings did not have the pin in the ring gap, but rather there was a small notch near the end of the ring the pin went in.

If yours is this version putting the ring in wrong way around will also lead to premature failure, if the engine will even turn. This may be why yours stuck at assembly.

Looking at the top of the piston the gap should be positioned in a counterclockwise direction from the pin.

Hope this helps.

Bill.

Bill,

Thanks for your wisdfom. When the new parts arrive I will read your advice again. Take care!

*rcnats*