I feel like a dope. I tore down my OS 50 SX for cleaning and now have lost compression. I know I screwed up the ring on reassembly. Are there any good articles on how to reassemble a ringed engine? I know on a car engine I would use a ring compressor but on this little guy the sleeve comes in from the top. I guess I have three questions: 1) What type of grease do you use when reassembling the engine? 2) What method does one use to remove/replace the ring from the piston so as not to damage/bend it? 3) I used a rubber mallet to push the sleeve down unto the piston during reassembly because I could not do it by hand. Is this a problem?

I apologize if this has been covered in the threads, I have done 3 searches and couldn't find anything. I would also like to thank you all for the wonderful advise that I have gotten in the past. It has not fallen on deaf ears and has greatly enriched my favorite hobby!

sounds like you broke the ring. remove the sleeve remove the piston and rod assembly. is the ring still in one piece? if it is consider yourself lucky. now take your rubber mallet and hide it. do not use rubber mallet use hands only. look at the piston ring groove real close. you will see a small pin in it. that is where the ring gap goes. put the old piston ring if it is not broken or a new one if it is. making sure the pin is lined up with the ring cap. now squeeze the piston ring by hand. notice how it goes all the way into the piston all the way around. if it does not the pin is not lined up with the ring gap. realign the ring gap and try again. put the piston and rod assembly back in the engine. oil the sleeve with after run oil, marvel mystery oil air tool oil whatever. Now MAKE SURE the ring gap is lined up and the ring will go all the way in. bring the piston all the way up in the bore and push the sleeve over the piston by hand while squeezing the piston ring with your hand. By hand only do not use a tool a hammer nothing. if it won't go on the the ring has rotated line it up again and try again. by hand only. Now that it is together open up a coca cola and continue putting the engine back together.

Dennis

Remember no hammer

Dennis,
Thanks for your words of wisdom! I should have check with you BEFORE I got out the rubber mallet. Sadly due to my ignorance, I have ruined the sleeve and ring. The ray of sunshine is that I will never do it again thanks to your post! What is even better is maybe, just maybe somebody like me will read this prior to thier engine maintenance and will avoid the same mistake. Thank you so much for helping me understand what must be understood for ringed engine maintenance!

As far as putting rings on or off. You fiddle with them gently until they do what you want them to do. Fingers only, no tools. The rest of the advice is exactly right. Some engines, K&B 4011, for example, do not have pinned rings. The couple of ringed engines I have fooled with have had a chamfer on the bottom of the sleeve which would compress the ring as you push the sleeve down.

Your right Jim, there was a chamfer at the bottom of the sleeve. (That's what gave me the no-so-bright idea of using a rubber mallet) I have been used to full size vehicle engines which I am finding have less and less parallels to these tiny beasts! It sounds like I manipulated the ring properly by your advise by gently using my fingernail to slip it over the piston head from one end to the other to put as little stress and bending as possible. My dreaded mistake was not to allign the ring and then think that force was normal in replacing the sleeve to get the ring to compress in the chamfer. I gotta really thank you guys from your input. I don't think there is another thread that addresses this issue. I just can't believe how fantastic a resource RC Universe has been. It has really put me intouch with experts like you and Dennis.

Well sorry it cost you a piston and sleeve but the good news is if you ever need to do it again you will know better. An expensive lesson for sure.

Dennis

ggrrrrrrrrrr[:@] when i took my supertiger 75g apart a few months ago that would have to be the worst experience ever and makes me mad to this day just thinking about it.....yeh the dang ring not going into the sleev[:@].....this help enuf to get my engine bak together....put the piston in the freezer for 10 minets and the sleev in the grill for the same time...this makes it a bit easier to get the piston bak into the sleev......oh gee it mad me mad trying to get that engine bak together it took so long[:@]

we just had this discussion the other day on another thread.......LOL[8D]

[link=http://www.rcuniverse.com/forum/m_4538314/anchors_4539289/mpage_1/key_/anchor/tm.htm#4539289]How to replace an engine ring?[/link]

the link within was very helpful to me.....

[link=http://www.raptortechnique.com/enginebearing.htm]Engine Bearing Replacement[/link]

hope this is as much help to you as it was to me........