Single ring piston

Has anybody used a wiseco single ring piston in a 92-01 cr250? Debating using one in my 01. I've searched everywhere and can't find much info pertaining to CR's. Thanks for any info

I had a 1996 cr 250 2 years ago and that's what I used. It worked fine with no issues... No holes needed to be drilled either. I just used the standard wiseco piston, nothin fancy. Give it a shot

I was looking at the racers choice gp piston. I race hare scrambles, don't want to lose any bottom end power. I know its kind of for high revvers.

Well I can't say for sure if it'll effect anything besides your pocket but the gp piston I believe has 2 holes in the front of it to let the pressure built up from behind the piston out, and I do believe that's the same type of piston Jeremy mcgrath used for his 96 but I'm not 100% sure of what effects it'll have... I'd say try it and find out would be the only sure fire way... I've never used anything but a single ring piston and I had flywheel weight in my bike and I only rode trails and I've never kept it highly revved, nor fouled a spark plug... Not sure if this helps any but if you got anymore question, shoot em up and I'll try to give my best input for you

I've seen some pictures of it, don't think it has holes in it. But it may. Guess I'll find out, going to give it a try I think just for the heck of it. Unless somebody chimes in against it. I figure I'll probably have to put a ring on it sooner than the two ring pro lites, but that really isn't an issue I like to clean my powervalve throughout the season

Well if you perform maintainance that well on your bike, I could almost guarentee that you'll be happy with it

Just an update on this if anyone is curious. I put a single ring racers choice in my 01 cr250. Got to ride it today.

It was super muddy and spots with snow and ice, so I had a hard time really getting a feel for the power. But the bike felt great. Didn't have my flywheel weight on, which I always do but didn't put it on yet after a new bottom end , but I didn't feel any loss in low end power like I read that I might.

The one thing that is definitely noticeable, is how much easier it is to kick over. Compared to the usual 2 ring pro lite that I usually run, it feels like kicking over a 125. Don't know if that's good it bad.

But the bike definitely rips. I'll add more when I get to ride again in better conditions.

Can anybody comment on the single ring being easier to kick? It is starting to have me worried that something is wrong.

Rode my buddies kx250 this weekend, and it was twice as hard to kick as mine, and that's how mine felt with the 2 ring piston.

On my '05 w/ a single ring, i don't find that it's all that easy to kick over when I have a fresh top end. I have to put all my weight down on the kicker if I want the kick lever to go all the way down and make contact w/ the footpeg.

Did you do a compression test at any point before or after rebuilds? What is it pushing now?


My 2000 put out 210 with a unbroken in double ring wiseco and stock jug/head. It's at 218 PSI now after 104 hours.

I did a compression test with a cheap $20 tester. Got 165, which also has me worried. But it runs great, I'm half tempted to take the cylinder off and inspect everything and put a new ring on it.

I just don't see what I could have did wrong. I had the cylinder replated, and put a single ring in it and broke it in as I normally would. Piston clearance was fine, on the tight side but ok.

Did you hold the throttle wide open during the test and kick it hard 5 times or more?

Yes. Only thing was I've heard you should do it with a warm engine, which I didn't do

Well I went riding Saturday. Came to the conclusion something is definitely wrong. It has decent top end power, but lacking considerably down low. Powervalve seems to functioning properly.

Going to put a new ring on it this weekend, hopefully it cures this problem. Just really disappointing, have way too much money in this bike.

Tore it apart last night. Ring was toast. That would explain the issues. It had close to an 1/8 inch of ring end gap. Seriously. I'm surprised it even ran. New ring on, would have liked to spent more time deglazing the cylinder, but racing tomorrow and was just happy to get it going. Now the question is, why, after only 8 hours on this ring, did it wear so bad?


single rings are for no compromise power in a race bike.


Single ring pistons have no real use in our bikes, anything less than a expert class racers at lorettas is better suited by a 2 ring piston. Lasts longer, better lowend power with less piston rocking in the bore.

That may be true. However, the 05-07 CR's come with single rings. Its a very popular mod on yz's. Thought I'd give it a shot, there really is no info on it for these bikes.

FWIW....I get 80-85 hrs use on my single ring... previously w/ a Wiseco ($23), now on NAMURA ring ($12).

General off road riding only, 44:1, Klotz techniplate.


Next piston change, however, I'm going to try the high dollar Wossner 2 ring piston set . Hope I see this 2 ringer go past 160 hrs.

KTM owners seem to be getting 200, even 300 hrs on theirs.

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