I've ordered a replacement piston ring and sleeve for my YS120. The engine has more than 350 flights on it, and is becoming worn out - no compression.

Anyway, I've got the engine apart, and have removed the piston ring from the piston, but I broke it during the removal process. I can't figure out how to get the piston easily out of the engine... can't get the connecting rod off the piston or the crank pin. I have access to the top of the piston and piston ring area with the sleeve removed.

Are there any secrets to installing a new ring? Or is it ....just be carefull not to break it...?
-Doug Brindle

Doug,

I recently had to replace a piston ring on my Fox .50. I assume the the rings are similar, and require similar treatment. I was also a bit worried, because my old ring also broke when I removed it. Somewhere on the web, I can't recall where, I saw a picture of someone installing a ring, and used the same method with no problems. I will describe it as best I can without a picture. Position the ring on the top surface of the piston, with the gap hanging just over the edge. From this position, you can carefully bend one end of the ring down into the groove, and start inserting it. Once the end of the ring is in the groove, you can work your way around, sliding the rest of the ring into the groove. The main idea is that you do not spread the ring open and try to put it in the groove from the side of the piston, as this will certainly break the ring. By bending it 'sideways', you don't end up bending it excessively, and it shouldn't break.

If I find the picture, I will post the URL. Good luck.

banktoturn

I lube up piston & ring grove, then using ring pliers slide ring over top of piston into grove, much easier than by hand as you do not take a chance of scratching side of piston with end of ring. Actually one should install ring in cylinder down about a inch and check the end gap, as too little gap & the ring can break, too much and you will loose compression.

While we're on the topic of rings..how long should it take to break in a ring. I installed one a little while back in my webra silverline 40 and ran a few tanks of fuel through it. It starts right away and runs good from idle to full throttle but still not much compression. What it the proper procedure to break in a ring? I ran a fuel through it, idle, half throttle, full, and back to idle again:let it cool down all the way and did the procedure all overagain a few times. I'm running 5% nitro but not sure on the oil content. There's lots of oil residue in the exhaust. Any Ideas. thanx

Thanks BANK TO TURN... I'll try it.
-Doug