Single ring pistons

[Navytigerfan]

84 200x, cousin put in a single ring weisco...It smokes like crazy, I was thinking a rebuild was necessary. But after talking to a few guys, they say that's how them pistons run... I was kinda confused because the bike feels like it has lots of compression. For it to smoke as bad as it does, I'd think it wouldn't hardly have any...And if the smoking is normal, does that mean I slap a regular 3 ring piston it without having to hone or bore the cylinder?

[fabiodriven]

I honestly can say I've never seen a 4 stroke engine with a piston that doesn't have an oil ring. I've seen countless 2 strokes with a single ring, but never a 4 stroke. I could be mistaken here, but I think you're cousin seriously botched this.

[M.Pargiello]

Uuummmm yeah, If it is a 4 stroke, you have at least one comp ring and an oil control ring.

Something isn't right..Are there port holes in the skirt? Seems he used a single ring 2 stroke piston..

[Navytigerfan]

http://www.dealtime.com/wiseco-honda-atc200x-wiseco-piston-50mm-over-atc-200x-81-85/info

Here's one... I believe...

[fabiodriven]

http://www.dealtime.com/wiseco-honda-atc200x-wiseco-piston-50mm-over-atc-200x-81-85/info

Here's one... I believe...

Again, I could be mistaken, but is that just a generic piston pic for that ad?

[Navytigerfan]

I'm honestly not sure... Could be... Seems I seen a single ring piston advertised for the 200x, but don't have time to look right now. I'll look later, see if I can find it. Maybe not, though... I just know it smokes way too much for me to ride, and I've never heard of a single ring piston before, but I figured they used them for racing or something, less friction, smaller, lighter piston... Along those lines...

[yaegerb]

On high-end racing cylinders you’ll find pistons with only one piston ring. I have seen a lot of single rings on two strokes as well.

Some advantages of one ring: A single piston ring allows for a higher RPM due to reduced friction, improves cooling due to lower friction and reduces the likeliness of piston ring issues.
Some disadvantages of one ring: Reduces the compression and can make the piston unstable

Typically, in the one ring set-up, the piston will last shorter and also stress the cylinder more due to its instability and the loss of compression needs to be equalized elsewhere (normally re-gained by decking the head).

In my opinion I would stick with the three ring set-up, expansion, compression and oil. Increased longevity and you don't have to modify the head for compression gains.

[fabiodriven]

On high-end racing cylinders you’ll find pistons with only one piston ring. I have seen a lot of single rings on two strokes as well.

Some advantages of one ring: A single piston ring allows for a higher RPM due to reduced friction, improves cooling due to lower friction and reduces the likeliness of piston ring issues.
Some disadvantages of one ring: Reduces the compression and can make the piston unstable

Typically, in the one ring set-up, the piston will last shorter and also stress the cylinder more due to its instability and the loss of compression needs to be equalized elsewhere (normally re-gained by decking the head).

In my opinion I would stick with the two ring set-up, compression and oil. Increased longevity and you don't have to modify the head for compression gains.

But have you ever seen a single ring piston on a 4 stroke?

[yaegerb]

But have you ever seen a single ring piston on a 4 stroke?

Nope, Never