05 YZ125 - Snapped powervalve, anybody else?

[Zenith]

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...

 

[MXP1MP]

No I haven't had any problem like that with mine, but it's an '06 so haven't had it long enough to really tell. But yamaha has been using this style of power valve since basically '94 in fact quite a few 125's now use this design cause it's pretty reliable. These freakin parts are exspensive from yamaha! like $150 per piece.

This is the first one I have seen

 

[Zenith]

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!

 

[MXP1MP]

If it was my bike I would replace it with new parts, I think it some how got stuck from maybe to much carbon build up or came out of alignment and has been that way for a while and the open/closing action finally broke it or maybe it contacted the piston, but it shouldn't have done that would of had to like come unhooked or something and some how tried to drop into the cylinder and I don't think it can totally. thats my guess.

I had some website link that some turner was describing to make notches on the holder area something bout the design didn't hold it good enough. But that was like a year ago I don't have it linked maybe I can find it again was like a dutch site or something.

Edit: I found the site scroll down and you'll find it kinda mixed with some other info going under he-ja tips under the tuning info link oh ya click the flag to make it sorta in english.

http://www.he-ja.nl/

 

[MXP1MP]

That pic on there of that clutch basket is really gonna make me up my search of getting an aftermarket one if it can do that stock as 125 my 144 is gonna only make it happen faster.

 

[nikki]

New powervalve for $124 here (select your bike, and the cylinder head diagram): http://yamaha.dgy.com/parts.aspx

Keep us posted if you figure out why it snapped.

 

[DLHamblin]

Its hard to say from the photo, but the one side at the break looks like it was galling (seizing?) as its bright aluminum in color and appears from the photo to have a lot of wear after the radius and before the break.

 

[Zenith]

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 :(.

 

[Fultoncm]

That SAME EXACT thing happened in my RM. Cost me a new piston kit and valve. Unfortunately the valve came into the cylinder a tiny bit and the piston hit it. But my valve looked exactly like yours.

 

[MXP1MP]

Maybe you might want to look into doing this instead? Check around I want to know more about this myself first I've heard of it, but this place claims Athena has a 144 kit now for the '05-06 YZ 125.

http://www.vrp-mx.com/ProductPages/WeeklySpecial/BigBoreKits/ws_bigborekits_athena.html

 

[NacNac250F]

Had my bike for almost 2 years and no problems with it. What kinda of oil do you use and whats your mixture? Some oil's carbon up more than others and maybe it got stuck.

 

[Zenith]

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...

 

[MXP1MP]

I'd still pick the YZ over the KX trust me I had some issue's with my KX blown bearing in the transmission your power valve issue with the YZ is easy a good $600 cheaper to fix and you don't have to split the cases and replace'em etc!! I would take your YZ issue over what happen in my KX anyday. Your issue with the YZ is cake compared to my KX problem, plus it's easier to take apart the linkage on the YZ no stupid cotter key for the rear axle like the KX. There's alot more going for the YZ then the KX. BTW the KX is a copy of the YZ power valve setup nearly a "carbon" copy you have to clean'em I think you know why you must clean them now. I clean mine every top end, yup! every time! so thats like every 30 - 40 hrs for me yea my KX valves could stick also and when they start to stick that means clean'em! The Athena kit's are suppose to have stronger valves over stock.

 

[NacNac250F]

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...

I dunno if it can affect powervalves, but i know that if you run two different oils they can seperate and mess up your motor. Possibly something similar happened with the powervalves, just a guess. Anyway it's a good thing that snapped instead of what I had snap on my bike the other day. The end of the rod that disengages teh clutch decide to break off and destroyed a bearing in the bottom end. Luckily the only thing it messed up was 2nd gear and some beaings and not everything.

 

[Zenith]

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 :).

 

[2smokers]

Had the same problem with my 97 rm 125, ended up costing me 900 bucks.