05 YZ125 - Snapped powervalve, anybody else?

Hey guys,

Just wondering if anybody else has had the powervalve snap in their 2005 YZ125 like mine in the photos below? If this is the only one I'll just put it down to a freak, if there's more then one I'd like to know if it's another YZ 'fault' to add to the list.

I took the cylinder off it earlier to change the piston ring and found the right powervalve wasn't moving up and down with the other one, it was just loose. It looks like it just sheered off, which is pretty strange because there should be no lateral load on it at all.

Next question his does anybody have a clever way of fixing it; I really want to ride tomorrow and Monday . It's aluminium which I don't have a welder for, so any other ideas? Drill and tap both sides and thread them together?


Let me know what you reckon...

I've now heard of a few more going the same way :(. The list of "faults" on these bikes is getting unfortunately long. Though I haven't heard of any problems with the 06 so at least they seem to be getting sorted...

Are the valves aluminium on older YZs?

I just don't get why is snapped, I don't see what could have put the load on it to cause that. The actuator is sprung so they should never be under any great force, unless they are being opened or closed too fast and coming up against the stops at high speed did it?

Anybody reckon it is worth trying to repair? Any thoughts on how? This one is scrap and new ones are expensive as MXP1MP said, so it's worth giving it a go I reckon, just not sure what's the best way to approach it.

Thanks!

Thanks for the link MXP1MP, though I didn't really want to see any more potential problems with this bike :). Has anybody had these sorts of issues with the 06 ones? I'll be looking for a new 125 soon enough; I love how light the YZ is but liking of the bike ends there, I wish Kawasaki would come out with a nice light frame :(...

I haven't had any more ideas on why it happened. There are rub/wear marks down each side of the valve, which you can't see in those photos, so I'm wondering if the valve had a bit too much side-to-side play and just jammed one time. Reckon I'll just buy a new one and see how it goes.

Thanks for the link nikki, that's the cheapest price I've seen! The Yam dealer here wants the equivalent of $225 for the part vs. $124 on that site. Only problem is you can't order through the site if you're outside the US and they don't reply to emails :(.

MXP1MP - I won't be keeping it for much longer so I'd just like to get it sorted so I can ride out the rest of the season on it. Then it's on to a new one or a KX125, depending on how many of these YZ horrors I remember when I go to order :). 144 does sound appealing though!

Fultoncm - Funny you should mention that but I was speaking to a local mechanic who said that he'd seen the problem a few times on RM125s!

NacNac250F - I was using Castrol TTS at 28:1 for the last 3 years, I switched to Motul 800 at 32:1 last weekend. The valve was moving fairly freely in it's 'groove' and doesn't have much carbon on it, so I don't think that was the problem, but maybe it doesn't take much carbon to cause it in the first place. Are they meant to be cleaned regularly? My 2nd last bike was a 00 CR125 in which the valve doesn't need to be cleaned, and after that I had a 03 KX125 which was rock solid all round so I never touched the valves in it either...

NacNac250F - I'm certain it wasn't the oil and the valve was fairly clean so I'm not convinced it was the fact that I don't take them out and clean them either.
You're talking about the clutch pushrod right? Yeah, I had that snap on this YZ about 3 months ago. Had to replace all the trans bearings, replaced the rod with a steel one to stop it happening again.

MXP1MP - Were you drunk writing that? :)
The linkage on the KX is FAR superior design to the YZ. Kawasaki actually made an effort to try and keep dirt away from the seals, I got away with very little linkage greasing on that bike. I think the first time it was taken apart was two seasons into the bike's life, and it wasn't even in too bad a way then! The bearings were practically destroyed in the YZ after the first season, in fact one of the bearing shells was broken when I took it apart and to add to that the Yam goons had damaged one of the seals when assembling the bike.
And, uh, I've had to split the cases twice already on the YZ. First time the shifter stopped bearing fell apart which destroyed most of the gearbox (the dealer covered the cost, but had I had to pay I'd put the price at €1500+). I rode the bike for another couple of months only to gave the clutch pushrod snap, which again destroyed all the transmission bearings, thankfully there were no gears damaged this time.

Now just in case somebody accuses me of being biased here :), I've had two CR125s, then a KX125 and now this YZ125. In terms of reliability and cost to run this YZ has been by FAR the most expensive and unreliable bike I've ever owned. A friend bought one at the same time as me and had pretty much the same experience, in fact we dropped our engines back to the dealer together after the shifter bearing going in both. Now I forgive the YZ a bit because it's such a light bike, but for me there's no denying they're badly designed, built build and badly finished. I was told this by loads of people before I bought the bike, but once you ride such a light bike it's blinkers on and I had to have one :).