When would you look at changing a piston ring?

[Jackflap]

What are your thoughts on changing piston rings, when would you look at changing one in an engine? Does it need to be changed?

[Andy from Sandy]

The reasons I can think of for ever needing to change the piston ring is if breaks or the engine is getting on a bit and has started to lose compression or you are changing the liner.

As you know the ring creates a seal with the liner and part of the breaking in process is a small amount of meterial is lost from the liner and the ring to create this seal. This may result in the liner not being perfectly round and the two parts are now a unique item due to the wear pattern.

If you have to change the liner because it got badly scratched for some reason then it would make sense to change the ring at the same time. If you break the piston ring and fit a new one then you should also de-glaze the liner to allow the new ring to work against the roughned surface to bed in.

[robgt]

I reckon that pretty much covers it!

Cheers,
Rob

[Jackflap]

The reasons I can think of for ever needing to change the piston ring is if breaks or the engine is getting on a bit and has started to lose compression or you are changing the liner.

Evo Andy that makes sense, changing it as the engine is getting on a bit could mean many things depending on how the engine is used I suppose, didn't know if it was something that would be changed if you were replacing bearings etc. But I suppose if it isn't broke don't fix it.

thanks for your reply

[Andy from Sandy]

didn't know if it was something that would be changed if you were replacing bearings

This suggests you have had to do it yet? When you have to and before you even start to take the engine apart read this

http://www.raptortechnique.com/enginebearing.htm

Making doubly sure to note that the piston ring fits in one position because of the pin in the piston. This is usually the reason for a broken ring.

[robgt]

Or these

http://50-tuning.com/articles/OS50HyperMax/index.asp

Cheers,
Rob

[Jackflap]

This suggests you have had to do it yet? When you have to and before you even start to take the engine apart read this

http://www.raptortechnique.com/enginebearing.htm

Making doubly sure to note that the piston ring fits in one position because of the pin in the piston. This is usually the reason for a broken ring.

My 1st hyper had 3 sets of bearings in over a considerable time and fuel usage but on the last set after about 3 - 4 tanks the ring broke and knacked the engine up (i put this down to me). At that time it was easier and cheaper to replace the engine. My post mainly came from a conversation I had the other day about preventative maintenance on two stokes and this topic came into conversation.

Just thought I'd ask the question on the forum to see what came back.

Personally I have used OS engines for 9 years mainly in planks and have had to do very little with them hence I use OS. The heli engine does seem to be high maintenance and easier to break by the user for many reasons...

[Jackflap]

Or these

http://50-tuning.com/articles/OS50HyperMax/index.asp

Cheers,
Rob

50-tuning.com is in my bookmarks at home and work...