Topic: is there a difference between high compression rings and just new rings?

[the technological J]

so is there gonna be a big differents in performance and price to get high compresion rings or is it worth my money to just get stock rings... will i notice it if im not racing .. i guess is my question?... i would love to hear some technical data if possible

[mlinder]

Not really sure what you are asking.

Rings don't add compression. They just keep the compression in the combustion chamber, instead of squeeking past into the case.
Poor rings can reduce compression because the clearances are bad, but all good rings do is keep explosions in the combustion chamber and oil in the crankcase.
I suppose you could have rings that were so tight that they'd let next to none of the combustion down into the cases, but then you'd have some other real bad issues.

[the technological J]

so rings either work or dont?... for some reason i thought that some kind of high performance rings raised ur compression... i guess i got this idea from a story about an old harley chopper whos compression was so high that on an attempted kick start was tossed over the handlebars

[mlinder]

That was due to high compression pistons.

It's true, as I said, that new rings will put compression where it's supposed to be, and worn rings lower compression  bit. New built engines just broken in do have higher compression than worn, but rings are there just to hold compression in, not add compression.

[J.Webster Designs]

what mlinder is saying is completely true.....

However, one thing that you should be looking into is the types of rings you are putting in. there are different types of rings out on the market that are made of different materials. some are great for higher performance engines, while others should never be in higher performance engines. There are also different types of oil styles of oil rings (one piece vs. three piece.) although, my experience comes from the automotive world and not bikes. so for all i know the stock rings from honda may be perfect for all applications. i doubt thats the case though.

[Bodi]

No, rings can't give you high compression (except by replacing leaky worn ones). Compression is just the ratio between the cylinder volumes with the piston down vs up, higher compression requires less space above the piston when it's at TDC: a high compression piston usually has a crowned rather than flat top, to fit snugly into the combustion chamber in the head.
Take any harley chopper magazine story with a few pounds of salt. High compression makes kick starting difficult, but has nothing to do with kickbacks. Trying to kickstart almost any engine with too much ignition advance will send you flying. It's not too bad with the SOHC4 motors - one little cylinder doesn't have all that much power and the electric start clutch drives the starter motor if you turn the crankshaft backwards, soaking up the kickback energy.
Old harleys with manual advance will send you flying if you forget to retard for starting, and the ancient British 500cc singles are responsible for many bruises and broken bones.

[the technological J]

is there any hidden problems i will run into if i convert to a highcompression piston? any reccomendations for a good one that isnt the super high priced performance ones? same for rings any good sources there?

[the technological J]

also if i hemi the heads will a high compression piston be lost if i dont get the head milled and brought back to "spec"? the reason i ask is i was reading the thoughts of hondaman and he talks about hemi-ing the head but then getting it milled 8 thou to bring the compression back to reccomended ratio... any thoughts or ideas on this mod?

[edbikerii]

Total Seal piston rings improve compression by keeping more of the compressed charge in the combusion chamber and minimizing leakdown.  Instead of having a gap where the ends of the ring meet, the ends overlap similar to a lap joint in woodworking.

I used Total Seal rings in my 1958 Jaguar XK150.  They worked well, and they cost less than 1/5 of what Jaguar rings would have cost me.  I would be concerned about using them in a high-compression, or forced-induction (turbo or supercharged) engine, as the rings are thinner where they over-lap, and may be more prone to cracking there.  Most SOHC4 Hondas have pretty low compression engines (with a few notable exceptions here on this forum), as do classic Jaguars.

[mlinder]

For which bike?
High compression can stretch engine bolts under heavy load/high rpm. Hemi-ing the head (removing material) will change compression a tad, since the overall combustion chamber is larger.

[the technological J]

For which bike?
High compression can stretch engine bolts under heavy load/high rpm. Hemi-ing the head (removing material) will change compression a tad, since the overall combustion chamber is larger.

prob the hondas the 750 and 550 im gonna tear them down this winter