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After market valves for YZ 250 F

By Rockyracer,
in WR250F/YZ250F/YZ250FX

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Grand Master

Birdy426

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I second the "Go with Stock" vote...but if you absolutely gotta have stainless, be sure you get the right springs, keepers, etc (stock won't be stiff enough), and cut the seats. As far as the guides, measure them. If they ain't worn or ovalized (ovulated?), they are fine.

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grungle

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What are the best aftermarket stainless steel valves?

I used kibblewhite valves from the TT strore on my '03WR250F. They have now done close to 6000km and I've only adjusted them once.

Sorry, I haven't tried any other brands so I can't really comment on "the best". Much like people that haven't tried stainless steel valves can't tell you if they're good or not...:ride:

And yes, you must replace valve guides. I did the springs, retainers and everything else in there at the same time, it all came in the kit from kibblewhite.

I have since done an '02 WR250 with stainless valves and that has been running for a year without a valve adjustment. If you want stainless, go for it, they've been good to me. ?

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smcdonn

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Ok so there are 5 votes for OEM valves and I am going to make it 6. I am not going to say that the stainless valves are bad, but there is a lot of work that goes into using them (cutting seats, heavier springs, etc) for no added benefit. I have a 04 YZ250f that I bought new and have never even adjusted the valves. The Yamaha valves are very good and there is no reason to switch to anything else. Now like mbraun said, if you owned an early Honda or Kawi/Suzuki 250f, there was much to gain from going to stainless valves due to an inferior design on their part.

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grungle

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I believe there is benefit in going to SS.

I'm planning on keeping the bike for a long time, so longevity is important to me. For those that aren't planning on seeing the next top end rebuild I understand this isn't a big deal.

I'm also of the opinion that SS valves are manufactured under a more "reliable" process. Surely everyone hasn't forgotten about the '06 yamaha valve problems already? Yes, they did the right thing and recalled those bikes that were affected, but so far every manufacturer (?) has had problems with Ti valves. They are a difficult and expensive part to make, and I didn't want to take the risk that I'd get the next bad batch and grenade my motor. I believe SS valves are easier to manufacture and are more tolerant of manufacturing errors.

Finally, I ride in very fine dust - they say the dust in outback Australia is the finest in the world - and SS valves are able to tolerate more wear without significatly increasing the risk of a sudden failure. They also wear in a linear fashion, unlike the non-linear characteristics of the Ti valves (once you're through that hardened Ti layer that's the end of them...)

They're not for everyone, but in those threads that ASK for info on SS valves I'm happy to provide my experiences, as I found it very difficult to find any information (other than "stick with Ti").

I hope that answers your question Rocky. ?

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oz_leper

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Grungle,

whats the performance loss on the heavier SS valves vs OEM (if you can remember).

I've done two top end rebuilds on my bike through no fault other than many hours (and kms) on the bike in pretty ordinary conditions (hot Aussie dusty summer) and at nearly $800 a pop I've been giving consideration to SS for next time it becomes due.

Who supplied the Kibblewhite kit?

For those that are voting, how many hours / kms / miles have been done on the bikes and under what sort of conditions? I find I get about 6000km out of a top end under my riding conditions, but that's only about 12-18months for me and I'd really like more...

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mbraun777

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I find I get about 6000km out of a top end under my riding conditions, but that's only about 12-18months for me and I'd really like more...

You do have a point. These bikes require periodic maintenance after few riding hours. Their big brothers the 450F's can go a bit longer. You are going to be in the engine every year to replace the cam chain and inspect your valve clearance at a minimum. As far as cranks go I was crazy religious about oil changes (3 to 6 hours max), cam chains, and got less than 200 hrs out of the first one.

Seems we can't escape replacing parts on these high strung engines.

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grungle

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Grungle,

whats the performance loss on the heavier SS valves vs OEM (if you can remember)

I didn't notice any performance drop, however I did put the YZ cam, JD jetting kit and heavy valve springs in, so I guess they could have off-set any losses the heavier valves caused. There may be a bit more noise, but you know how paranoid you get when you put it back together - you're looking for anything out of the ordinary...

I've done two top end rebuilds on my bike through no fault other than many hours (and kms) on the bike in pretty ordinary conditions (hot Aussie dusty summer) and at nearly $800 a pop I've been giving consideration to SS for next time it becomes due.

Who supplied the Kibblewhite kit?[/Quote]

SS isn't neccessarily cheaper once you buy the spring kit. I think mine was around the $800AU mark as well (including $200 for the head shop to fit the valves). The kit came from the Thumpertalk store.

For those that are voting, how many hours / kms / miles have been done on the bikes and under what sort of conditions? I find I get about 6000km out of a top end under my riding conditions, but that's only about 12-18months for me and I'd really like more...

I got 11,000km out of the stock valves under VERY dusty conditions. Mainly trailriding, but quite fast (keeping up with all the WR450s). Often on the rev limiter.

The SS have now done about 6000km, including a couple of 3-hour enduros in THICK dust (like riding through soup). Finished 3rd and 5th in pro lites, so the bike is still competitive. No adjustments yet either.

They seem to be doing well for me, and even once they start wearing down I'll be much more comfortable simply shimming them back into spec. They should wear at a constant rate too, so it will be longer intervals between shimming.

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Grand Master

jjgixxer

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Check out the new Wiseco valves in the dirtbike catalogue section. www.wiseco.com. They are "premium OEM replacement". I know they are single piece Ti valves, and have been working well for people. Wiseco is also showing cam chains available. Valves are $139 each. How does that compare to OEM? Are OEM valves one piece?

Don't buy wiseco ti valves. TT very own Crob and drob was running them in there race bikes. Well he has had 2 of them break. They now are switching back to oem valves. ?

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Birdy426

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Check out the new Wiseco valves in the dirtbike catalogue section. www.wiseco.com. They are "premium OEM replacement". I know they are single piece Ti valves, and have been working well for people. Wiseco is also showing cam chains available. Valves are $139 each. How does that compare to OEM? Are OEM valves one piece?

OEM Ti are about 60 bucks a piece. I believe they are two piece, but wouldn't bet my wife...um...life on it.

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CBDaddy

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OEM Ti are about 60 bucks a piece. I believe they are two piece, but wouldn't bet my wife...um...life on it.

Make sure you aren't comparing apples to oranges. Wiseco valves are forged one-piece Ti valves. The OEM Yamaha valve is not forged, it is a 3 piece spun-weld unit. That is why the heads pop off in extreme cases when you load/over rev the motor. If someone broke the Wiseco valves, most likely there was something else causing the problem, like the valve seats not being cut right or the valve stems were worn out. One piece forged valves don't just break for no reason.

With regards to price, from what I hear, Wiseco valves are paying for themselves. Guys are getting twice the life out of them and just the labor savings alone makes them worth the effort, let alone, the resistance to failure being a forged 1 piece unit.

I'm no expert, I'm just trying to provide fair information so we are comparing apples to apples.?

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