change 1 set of rings?

just wanted to know if it is cool to just change 1 set of rings, i am oil fowling on number 4, took off the heads,
not the jugs yet, but all the pistons are tight , no wiggle.
with rings over $60 a piston was wanting to know if i could change just the rings on number 4, thanks

hap1968 wrote:

just wanted to know if it is cool to just change 1 set of rings, i am oil fowling on number 4, took off the heads,
not the jugs yet, but all the pistons are tight , no wiggle.
with rings over $60 a piston was wanting to know if i could change just the rings on number 4, thanks

you can do anything you want.....but why? imo, unless the rings are practilly new....change em all. jmo!...Joe

Did you verify that the problem isn't valve related?

It would suck to change the rings and still not fix the problem. 30 year old valve seals let a lot of oil past if they've never been changed.

On my 750 twin, oil fouling the plugs has always been caused by a bad valve guide seal. The oil drips down after you turn it off and fouls the plugs. Every time I had to tear mine down it was bad valve seals. I didn't have to rebore until I hit 80k miles.

my compresion on all 4 was 160, all the valves look the same, the numer 4 piston top is cleaner
then the rest, all the valves have the same little bit of wiggle in them when i put them in the guide, every thing looks great thats what puzzles me.
will a bad oil ring affect compression?

Rings are damn expensive! I bough some for my bike, and I though I was buying the whole set for that price for some reason. Got them in the mail and was dissapointed. So I didnt put em on. Just honed the cylinders, lapped the valves, and installed new valve seals.

With those compression numbers I would say your rings are good. But a bad valve seal on that cylinder will not show up on a compression test becaust the valve, the valve seat, and the rings do the sealing of the combustion chamber.

My guess is valve seals, possibly valve guides but less likely. Valve seals would be a cheap fix.

Also if you do take the jugs off and dont replace the rings, i would check them out, and hone the cylinders.

good luck


-Luke

160 psi is great for a 550. When you get down to 120, then worry about it.

Do a hot dry compression test(all spark plugs removed, and a completely charged battery), then a hot wet(adding a little oil in the spark plug hole) to see what the difference is.

If you remove the head to replace rings, do all of them, not just one. In the process, have the head rebuilt as well. Do it once, do it right, and be done with it.