New piston ring recommendations?

[Diskman01]

My 78 E is burning oil now. It had a pretty hard life with a PO. Just a tad over 43K on the clock. Nightly drives around town with some interstate and I lose a quart. I replaced the valve seals a year ago and lightly lapped the valves. That cured my idle smoking problem.

Last compression test was 160-170psi cold. Thinking I have worn oil rings and/or seized rings with the amount of carbon I removed when I had the head off doing the valves. Sheesh.

Guess the best way will be to just pull it apart and measure before ordering rings? Would I be OK just going to the next oversize rings and filing the ends to fit? Any sources on a complete set of rings for reasonable? Any other input?


Pics of the head and de-carbonizing last yearish..


Piston de-carboning. Permatex gasket remover, B12 Chemtool and purple scotchbrite pads work wonders.

[TopCatGr58]

Hey there,

Were your comp levels obtained before or after your decarboning?? I'm going to assume you meant AFTER the cleaining. Those are great amounts of compression for a stock engine....but excessive carbon buildup can artificially elevate the comp levels.

Now, while you had the heads off would have been the time to micrometer the cylinders to check for out of roundness/wear, which could have told you whether you could have gotten away just a honing and some first oversized rings. HOWEVER, they are getting quite rare and are NOS by Yamaha anyways.

You mentioned the damage done by the PO, but you didn't say whether the bike was stored or sat for a long time before you got a hold of it. If so, then the oil rings could be gummed up and not wiping properly?? BEFORE you go tearing it down, you can try to run some Marvel Mystery Oil in it for a while to see if that can help loosen possibly stuck rings.

Also, you didn't say what oil you are running?? IF SYNTH...that could be part of the usage, as well as if it's too thin...ie. 10-40 vs. 20-50, which could also allow it to slip past the oil rings more easily!?

So..after doing all of this and you still have lots of oil usage, then doing a full BORE job may be your only alternative for available parts. Ebay has a 1196cc big bore kit made in JAPAN for $150.00, pistons, rings, head gasket, wrist pins and keepers complete, you just have to pay the CYLINDER BORING fees at your local machine shop, and of course do the labor for disassembly/reassembly! The pistons are CAST and not forged like the $$$ WI$ECO ones, but so are the OEM pistons, and work just fine, just ask ViperRon....he's installed them.

T.C.

[mack]

This is

what I installed in my spare motor. You'll need to deglaze the walls of the sleeves with a honing ball first. Check for out of round first.
http://www.ebay.com/itm/YAHAMA-XS110...lVgggB&vxp=mtr

[Diskman01]

Were your comp levels obtained before or after your decarboning?? I'm going to assume you meant AFTER the cleaining. Those are great amounts of compression for a stock engine....but excessive carbon buildup can artificially elevate the comp levels.

Yes, they were BEFORE I cleaned it up. That was rattling around in my head the other day too. I will pull new numbers tomorrow when it cools down completely. Just got done with a 100 mile ride around town with the wife.

Now, while you had the heads off would have been the time to micrometer the cylinders to check for out of roundness/wear, which could have told you whether you could have gotten away just a honing and some first oversized rings. HOWEVER, they are getting quite rare and are NOS by Yamaha anyways.

DOH. I just bought a new cylinder mic a few years ago too. Never crossed my mind. Easy enough to pull the head this weekend again. Rain through Memorial Day. ugh.. I was unaware of the first oversize getting rare. Was reading threads on here about sets running ~$50. Day late and dollar short..

You mentioned the damage done by the PO, but you didn't say whether the bike was stored or sat for a long time before you got a hold of it. If so, then the oil rings could be gummed up and not wiping properly?? BEFORE you go tearing it down, you can try to run some Marvel Mystery Oil in it for a while to see if that can help loosen possibly stuck rings.

Bike was ridden hard and then put away wet. I bought it after it sat for a year outside. I have about 15K on it since I bought it. Been on a few major road trips also. At this point, I would rather replace pistons/rings than try MMO. Don't get me wrong.. I love me some MMO.

Also, you didn't say what oil you are running?? IF SYNTH...that could be part of the usage, as well as if it's too thin...ie. 10-40 vs. 20-50, which could also allow it to slip past the oil rings more easily!?


Plain old dinosaur squeezins. Rotella 15w40 at first, then switched to Valvoline 20w50 conventional motorcycle blend a few years ago. Lately I been changing and topping off with SuperTech 20W50.

So..after doing all of this and you still have lots of oil usage, then doing a full BORE job may be your only alternative for available parts. Ebay has a 1196cc big bore kit made in JAPAN for $150.00, pistons, rings, head gasket, wrist pins and keepers complete, you just have to pay the CYLINDER BORING fees at your local machine shop, and of course do the labor for disassembly/reassembly! The pistons are CAST and not forged like the $$$ WI$ECO ones, but so are the OEM pistons, and work just fine, just ask ViperRon....he's installed them.


Hmmmmmm. I have seen those kits on eBay and read the threads here. I will make a call to the place in town that worked on my old Honda a while back and get pricing on boring and possibly decking. I'm always looking for more "oomph", but I still plan on those 1000 mile trips so reliability is nice.

Thanks for the input!! I think I will look into the BB kit and do some more research on that path. I have an extra 78 complete motor with a claimed mileage of 60K for parts.. Maybe use the jug from that one for the BB and keep my original one stock for now.