YZ144 kit

A good friend has one on his yz 125.. Hes had nothing but problems.Hes had it rebuilt in just 4 months 3 times. Its in peices now and hes looking for a stock cylinder. I know some that have had no problems but hes had nothing but issues with it.

I don't know about the 144, but I've had a YZ167 since 2003, that bike is amazing. I've tried to sell it a few times, but can't seem to make myself.

I dont have a 125, but my YZ250 was massaged to a 285 by Powerseal in PA. Haven't had a single issue with it. Ringed it once at 30hrs and have ridden the shit out of it in some of the NW worst events. It's rock solid


I know the 1/8 liter pingers are another animal altogether, but I would go for it.

We put the Athena 144 kit on my sons YZ125 and he LOVES it.
The key to keeping it from being problematic is to not go with a high compression piston.

Doesn't really add a lot more in the way of flat out speed but the power curve is much better.
It has more of a smooth roll into the power rather than having to just keep it pinned and clutching it all the time.

Much better off the gate as well.
I highly recommend the Athena kit as it bolts right on there without any issue.

We had Jesse Williams at Williams Motowerx (member of this site, BTW) build a 144 motor for my son's '05 YZ125. AWESOME bike! Jesse is very helpful with any questions you might have, before or after....little tweaks he can do regarding pump gas, the kind of power you want it to make, jetting, etc. I can highly recommend Jesse.


Jesse's set-up isn't a "kit". You send him your motor as the cases need to be slightly modified for the bigger bore. I've heard the porting on the Athena kit leaves a little to be desired.

I had the 167 kit from RPM and it was bullet proof and the most fun bike I ever owned. Rick Peterson sold RPM and I cant remember what the name of the company is but it was well worth the money.

my 125 has had a broken power valve for a while now

nooo top end, maybe thats why its been boggin? haha yz125s are goooood when theyre ran right

We went with a 134 when we trashed a cylinder....it was great

Maxpower in Pa.

Radad, you can give me a call, Jesse 414-467-6199.

This is my take on the Athena kit... and I'm sorry if it seems like I'm bashing it.. but just telling it like I see it.

They take there 125 cylinder and bore it bigger, no porting changes for the bigger bore. That to me is a no,no. Second the local guy by me that had one continually went through o-rings in the head gasket. Head is a 2 piece design and a little finicky.

I modify the stock cylinders and heads, plus have to mod cases. Just give me a call and I'll give you the lowdown.

Ya Athena is what my buddy has hes had lots of issues but seems there are people here have none so go figure.