oh holy piston rings !

[collind]

How would a person go about getting piston rings for these bikes... what information would you have to match with a current bike to get working rings ??? ?  I really appreciate any help with this issue

THANKS! ;D

[sdinino]

I think I recall Humber saying he used rings from an Opel... but I don't think they'd be any easier to come by in the states. However he's trying to get an order together for overbore piston/cylinder sets, so maybe that's an option.

[Rick G]

I seem to remember that D.T.  researched this out last year.  If I remember correctly  standard rings were not available , but  1 st over were .  rings can be sized by filing the end gap , but you need to be careful and don't over do it. Maybe D.T. will chime up on this subject

[collind]

When you say next size over, what rings are you talking about? (for what bike)

and other than a matching bore size, what other criteria would you need to fit with another bike or car or maybe even something like a jet ski would work.

And I have 1 more question about the piston/rings... what is the 3rd (I think) ring looking object down that looks like it has two metal rings with a springy (or wavy) piece of metal inbetween? ?Also, if you found another engine with a cylinder of the same bore and the width of the rings is larger, could you simple grind it down (assuming you can grind it evenly)

Also, shouldn't the diameter of another piston ring be the same for another engine if the bore is the same? ?I doubt the depth of the grooves is significantly diffirent and if the width of the rings is smaller, could you stack 2 on top of each other?

hmmm that is actually more than just 1 question isn't it? ?Thanks for the info!

P.S.  Where are you D.T.? (i dont want to seem pushy though)  ;D

[yamy]

 ::)

You cannot use rings from a jet ski. The two cycle ring is not correct to use in a four cycle engine (with some odd exceptions). The Jet Ski OEM ring is a tapered ring, with a chrome face, and both top and second are the same dimensionally.

Rings in a four cycle engine have very specific dimensions, geometries, and materials, and it is not as simple as plugging in another ring. Humber was able to find an Opel ring that nearly matches the OEM Yamaha ring (which is probably NPR, Riken, or TP manufacture). However, it is taking a chance to assume that they will even work in place of the Yamaha ring without thorough knowledge of the face geometry, ring material, face treatment, radial wall, width, tension, and I could go on...

Ring groove depths vary tremendously depending upon the design of the piston, and surrounding interfaces. Ring position on the piston direcly affects function, with regards to fuel burn, and operating temperature range. So, we see, it is not very simple...

Do not stack one ring on top of another to function as an oil control ring! The oil control ring (the three piece ring), is specifically designed to do what it is called, control oil. The two small "rails" move like a windshield wiper when the piston travels up and down, reversing thier wiping angle as the piston reciprocates. This scrapes excess oil from the cylinder bore, and prevents too much oil getting to the second scraper ring (which also srapes oil from the cylinder wall, preventing the oil from traveling further up the piston and into the top ring or combustion area). The "seperator" helps this function, look closely at the geometry with the seperating nubs that support and seperate the rails, while also providing the room for the necassary movement.

So, piston rings (and pistons, and cylinders, etc) are not such simple things.

[Dave T.]

Did you try your local Yamaha dealer?  ??? That's where I got mine. Part # is 28V-11610-00-00, $32.08 each piston.

I tried to get oversized pistons and rings, so I ordered the 2nd oversize which was .040" over standard. The told me 2 weeks later they don't make them anymore. I don't think they make standard pistons either.

I was reading in my old cycle world that the put a "special" coating on the piston rings on the 1983 model. I am not sure what it does (cuts down on friction) but I would try to get a 1983 set of rings.

Check www.bikebandit.com and see if the parts are discontinued or not.

[collind]

Sorry about all that crap  I feel like such a complete dumbass now...

When I went to bikebandit before I accidentally searched for the piston set part number :)

I just tried it again and the 82 model ring set is only 32.72

Well, at least you got me to go back and get my head outta my ass eh?  Also I really appreciate all the info on pistons and rings too  I had no idea what the oil control one is or about the complexity of the pistons... sooo...  There is a pretty high educational value to all this, even if i dont get it working :)

[collind]

BUT!!! now that all the experts are here, got any info on a replacement ignition and gas cap?  I have the small round ignition unit I just need the lock that mounts on it. along with the gas cap... and I also understand that you can get standard helmet locks so I dont need to worry about that

[Rick G]

No problem, we are here to help!  You may find a serviceable , used , complete switch  on ebay (there have been a couple in the last 2 weeks) o in the for sale section of this site. As to pistons and rings , if you get stuck , email me, I have a couple of engines I'm tearing down  and  probably can come up with used pistons , rings and cylinders  to get you going.