Piston ring question

Jimmy Cincinnati /

So I was installing a freshly bored cylinder on my Yamaha Rt 100... I know not a moped. So the new piston came with what I will call a wrinkle ring that goes under one of the piston rings. After looking it over for a bit I came to the conclusion that it should go on the lower ring... additionally one of the rings came with a wider ring gap so I put that ring on the top. Was my conclusion right? Anyone have any guidance on that odd ring?

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Re: Piston ring question

Sounds right, like oiling ring on bottom groove. Someone here should know for sure.

Re: Piston ring question

You need to find a factory service manual showing the cross section of your rings and piston so you can see the shapes and get them right. The grooves in the piston match the rings. The rings also may have a bevel. I had to use a jewelers loup to see the microscopic markings on my Suzuki rings. Messing this up will ruin your day.

Re: Piston ring question

Yup yup ring expander went on the bottom on my Yami. It wasnt the same model as yours but I'm pretty certain.

Re: Piston ring question

Overpriced Parts /

It’s a ringer expander, some people choose not to run them,

Looks like Wiseco pistons don’t use them but they’re forged,

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I use Wiseco forged pistons if available for dirt bike overbore jobs because it measures perfect everywhere making a easy job for the borer, more dimensionally stable then cast, better job, way better service life, Compression and performance too

Re: Piston ring question

Not a big fan of forged pistons, in my experiences wiseco is a cheap alternative

Re: Piston ring question

The expander does go in the bottom landing .

If look look , you'll see that the ring on the right is narrower ( inside to outside ) . That ring goes over the expander in the lower landing the leftover ring goes in the top landing .

Re: Piston ring question

How their stacked on the picture on the box isn't how they go. Wow I would have blown that thing up quick

Re: Piston ring question

Overpriced Parts /

> river 2strokes Wrote:

> -------------------------------------------------------

> Not a big fan of forged pistons, in my experiences wiseco is a cheap

> alternative

What experiences? What bike?

I’ve used them in several Japanese dirtbike/enduro bikes had wonderful results and so did the machine shop who did the boring.

Got 2x the hrs/mi over cast pistons especially with the overbore, usually when you overbore you have a thinner cylinder wall (especially after the second or third overboard) and not as perfect as factory Unless you get a really skilled professional/shop so most times less service life then Factory fresh topend

Re: Piston ring question

> Michael Gamba Wrote:

> -------------------------------------------------------

> How their stacked on the picture on the box isn't how they go. Wow I

> would have blown that thing up quick

The piston in the picture on the box is a 4-stroke piston.

Re: Piston ring question

> Michael Gamba Wrote:

> -------------------------------------------------------

> How their stacked on the picture on the box isn't how they go. Wow I

> would have blown that thing up quick

Piston on the box looks like a 4 stroke piston.

Re: Piston ring question

> EH FCC of the QCB Wrote:

> -------------------------------------------------------

> Piston on the box looks like a 4 stroke piston.

Because it is .

Re: Piston ring question

Jimmy Cincinnati /

Thanks for the info guys, I put the expander and the thinner ring on the lower rung, seems to be doing great so far!

I was going to post a video of the bike running but having issues getting the Video to load.

Re: Piston ring question

Up load to YouTube , then the link here in the reply box .

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