steel valves in 426


7 replies to this topic
  • treukauf

Posted March 20, 2005 - 05:19 PM

#1

Wow in my search for a new bike I've been trying to weigh in rebuild costs. The titanium valves in the 01 426's are not cheap, matter of fact they aren't even reasonable. Will the 00 steel 400 valves fit when its time to rebuild seeing how they are 1/10 the price? How reliable are the ti valves, can i expect an 01 426's ti valves to still be good today.I know there are a lot of variables. thanks

  • 99wr400

Posted March 20, 2005 - 06:15 PM

#2

the head is the same for the 426 and for the 400, so the steel valves should fit, but might not match up with the springs and such in the 426 titanium valve head.

  • Sylvain

Posted March 21, 2005 - 08:04 AM

#3

I read somewhere that there is a Stainless steel valve kit available for the wr or yz.

wr 426 2001 VS wr 426 2002 VS wr 450 2003 etc..

Anybody know anything about this kit ?
What mods have to be done to the head, if any ?

:)

  • R_Little

Posted March 21, 2005 - 08:43 AM

#4

The stainless valves are suposed to last much longer and hold the valve clearance better too. Called KIbbleWhites or something like that.

Edco put them in my bike the last time I think.

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  • treukauf

Posted March 21, 2005 - 01:36 PM

#5

I would really like to know a price on these as i'm sure this far a long i'll probably be looking at a rebuild. Most of the bikes I see really haven't been maintained exceptionally

  • Dan_from_HB

Posted March 21, 2005 - 05:20 PM

#6

Cost to replace ti with ti is about the same as replacing ti with ss. To my knowledge, no one offers steel valves for 426. But I haven't looked, just discussed with several knowledgeable people.
Springs, caps, and keepers are different for ti valves, so they are likely not interchangeable. If you go with ss, you will likely have to change springs, caps, and keepers anyway to keep valve assy weight in the ballpark of the ti units. Otherwise, you can't use the same rev limit. Too many parts can attempt to occupy the same space at the same time. That's not good.
SS valves tend to wear out the seats a little faster than ti due to the harder material. You can have special seat materials inserted, but heads aren't very expensive. The ss valves will dramatically outlast ti anyway.
I'd buy with the intention of putting ss valves in it, especially after 50 hrs on the engine. I'd also negotiate with seller accordingly.
I have a '00400, so I'll just replace with factory stock. They work great in all respects.

PS: some 426/450 units had very limited life on springs anyway. I wouldn't do a valve job without new springs under any circumstances.

  • woods426

Posted March 22, 2005 - 06:13 PM

#7

Cost to replace ti with ti is about the same as replacing ti with ss. To my knowledge, no one offers steel valves for 426. But I haven't looked, just discussed with several knowledgeable people.
Springs, caps, and keepers are different for ti valves, so they are likely not interchangeable. If you go with ss, you will likely have to change springs, caps, and keepers anyway to keep valve assy weight in the ballpark of the ti units. Otherwise, you can't use the same rev limit. Too many parts can attempt to occupy the same space at the same time. That's not good.
SS valves tend to wear out the seats a little faster than ti due to the harder material. You can have special seat materials inserted, but heads aren't very expensive. The ss valves will dramatically outlast ti anyway.
I'd buy with the intention of putting ss valves in it, especially after 50 hrs on the engine. I'd also negotiate with seller accordingly.
I have a '00400, so I'll just replace with factory stock. They work great in all respects.

PS: some 426/450 units had very limited life on springs anyway. I wouldn't do a valve job without new springs under any circumstances.



Why couldnt one just use the oem steel valves, springs, etc out of a 00 426 instead of going with the more expesive SS kibblewhites? Like you said, they work great in all respects. As far as I know, the 98-00 400/426 all used the same steel valves etc. in the same head until they switched to the Ti valves in 01. Im also pretty sure that the 01-02 426's use the same head as the 98-00's do. The valve head diamer is 27mm int.and 28mm exh.for both the steel and Ti valves. Im not 100% sure the inside guide diameter is the same for the two, but the part numbers are the same for both the 00 and 01 guides, so I would assume they are the same guide which in turn would also lead me to believe the stems of the steel and Ti valves are same size. Ill bet as long as you swapped out the all the stuff, springs caps, keepers, seals for the steel oem valve set up from an earlier Yz it should work. You do have a point about the rev limits, but for me that dosent really matter as I ride strictly trails and my bike rarely sees past half throttle. I do wonder if the 00 and 01 bikes share the same rev limit though?

I have an 01 YZ 426 that two of the Ti intake valves are fading fast on, so I have to do something about it soon. Just the thought of spending 90+ per valve for Ti is a bitter pill to swallow, so I might just try the eom steel valve swap myself. :)

  • Dan_from_HB

Posted March 22, 2005 - 08:10 PM

#8

Why couldnt one just use the oem steel valves, springs, etc out of a 00 426 instead of going with the more expesive SS kibblewhites? Like you said, they work great in all respects. As far as I know, the 98-00 400/426 all used the same steel valves etc. in the same head until they switched to the Ti valves in 01. Im also pretty sure that the 01-02 426's use the same head as the 98-00's do. The valve head diamer is 27mm int.and 28mm exh.for both the steel and Ti valves. Im not 100% sure the inside guide diameter is the same for the two, but the part numbers are the same for both the 00 and 01 guides, so I would assume they are the same guide which in turn would also lead me to believe the stems of the steel and Ti valves are same size. Ill bet as long as you swapped out the all the stuff, springs caps, keepers, seals for the steel oem valve set up from an earlier Yz it should work. You do have a point about the rev limits, but for me that dosent really matter as I ride strictly trails and my bike rarely sees past half throttle. I do wonder if the 00 and 01 bikes share the same rev limit though?

I have an 01 YZ 426 that two of the Ti intake valves are fading fast on, so I have to do something about it soon. Just the thought of spending 90+ per valve for Ti is a bitter pill to swallow, so I might just try the eom steel valve swap myself. :)


If they will fit, I'd go for steel. 2nd choice ss. Ti would be my last choice since you'll find yourself back in the same boat again in 50+ hours. Just remember, length, diameter, shape, seat cut, and groove for the keepers all have to be the same.
As for rev limit, you can keep same limit if you use ti caps, keepers, and the right springs. If it was me, I'd discuss with Kibblewhite before buying anything. You ultimately want each valve assembly to weigh the same (valve + spring + cap + keeper) in order to keep the same rev limit. Remember, it's your ignition that controls rev limit. You don't want to rely on your right hand. Too high a limit for the mechanicals, and you might float the valves. You don't want that to happen under any circumstances.
Stiffer, lighter valve springs are likely necessary.
Yes, the 2000 has a lower rev limit than anything with Ti valves. About 1000 rpm less, according to the WR Master.




 
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