125-200cc 06 CR125 to 144

Hey guys. Wanting to build a 144.

Is there any aftermarket kits for these?
Or is it possible to track down and 2nd hand head and barrel to get one bored out and ported?

So far I can only find yz 144 athena complete top end kits

I dont want to sacrifice my original cylinder and head. Want to keep it as a spare.

Cheers

Husky sells the complete 144 setup as a kit, but it's a bit spendy ($900?). Most folks just have the stock jug bored and powervalves modded to go 144. Wallybean, the Montana Tiddlerman, can do the conversion for a good price, and he has impeccable attention to detail. You also might get a little massaging of your squish and ports whilst he's in there. If you really need to keep the 125 as a back up, then you could simply find someone parting out a 125 and snag the top end to send out for mods. I just picked up a 2000 125 cylinder, head and powervalve assembly for $200 and shipped it out to Montana for a 164 conversion (gotta buy pre-2008 for the big big bore. Any year can get the little big bore). I can't wait to put it in this winter. Plus, I'll still have my 2008 125 setup to put back on the bike when I finally sell it for a new WR (which comes as a 125 with a complete 144 included in the crate. I'll have the choice of 125, 144 or 164!!! Life is good...)

Good plan!

So what from what model top ends are interchangeable?

Oh and also you say small bore and big bore. How small is the small bore? Is that 144?

Yes, I meant the 144 was the little big bore, and the 164 is the big big bore.

I'm pretty sure that your 2006 cylinder can be bored to either 144 or 164. It's up to you. The 2008 and newer cylinders have a different port layout, and they for sure cannot accomodate the 164. I think they can accomodate the 144, however. All cylinders are interchangable going all the way back to the late 90's I think. Hopefully someone else will chime in with the exact year.

I have an 07 125 cylinder that I will be posting soon. It has the powervalves but not the rest of the hardware.

Ah ok sweet. I'll keep an eye out.

Thanks for the help guys.

'98-'07 are the cylinders that bore out as far as 62.50 mm with no problems. The OEM 144 cylinders can be bored to that dimension after the back side of the rear transfer is welded up and then re-ported after boring. That is the project that I have been working on this summer thanks to Tim Troffer, who donated a cylinder for experimentation. The '08 cr125 and 09 and later 125 cylinders are really tough because of the depth of the bore holes for the power valves. It is really tight in there to get those welded up successfully. I am going to try another possibility for those cylinders this winter but don't hold your breath. JFYI

I think the complete factory 144 can be had for under $700. Motosportz might still have some left.

I've been looking around for a 58mm (144) pistons, can't seem to source one. What piston does these use? Can't see any for cr/wr on Athena/Wossner or Wiseco.

You can use the yamaha yz144 piston that both wiseco and wossner sell. It does have a slightly raised dome with an initial bevel so you need to check your squish and adjust accordingly. Otherwise that piston is a great match. You can also just source the stock oem husky 144 piston. It is a really nice piece if a little more money. It is harder to bump your compression with the stocker because of the flat un-raised or domed piston. I have had excelent luck with either brand of aftermarket piston kits for this application.

Wossner it is! I also have a Yz 144. How easy is that!