Valves made of?


7 replies to this topic
  • pYura

Posted July 06, 2008 - 11:55 AM

#1

Steel or Ti?
ps.: couldnt find it sry.

  • sportbiker929

Posted July 06, 2008 - 11:59 AM

#2

intake valves are Ti

  • pYura

Posted July 06, 2008 - 12:01 PM

#3

Exhaust are steel?
Is it same with every year?

  • SXP

Posted July 06, 2008 - 01:05 PM

#4

98 and 99 are ALL steel. 2000 (including the 2000 WR400) and on are ALL Ti. There was never a mix of Ti and Steel - it was one or the other.

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  • lixno

Posted July 06, 2008 - 03:16 PM

#5

98 and 99 are ALL steel. 2000 (including the 2000 WR400) and on are ALL Ti. There was never a mix of Ti and Steel - it was one or the other.


I think that for the 2000 models only the YZF 426 had titanium valves. The WR went titanium next year (2001) along with the cc increasement.

  • grayracer513

Posted July 06, 2008 - 03:24 PM

#6

I think that for the 2000 models only the YZF 426 had titanium valves. The WR went titanium next year (2001) along with the cc increasement.

No, the 2000 models of both the YZ426 and the WR400 had steel valves. The 2001 and later models of both the WR and YZF had Ti valves.

  • shrekka

Posted July 06, 2008 - 07:10 PM

#7

i went from Ti valves to SS valves in my 2002 YZ426, mate the power is unreal..
actually i cant feel any difference in the power...l would recommend SS over Ti valves anyday

  • grayracer513

Posted July 06, 2008 - 07:59 PM

#8

There is no real wear issue with Yamaha Ti valves. They are, however, about 4 or more times the cost of Yamaha OEM steel valves, and they way that they wear is quite different. The steel valves are hard faced, but it is done by a metallurgical process that creates a shell up to .003" deep. Even if that hard face wears through, the steel base metal is fairly hard on its own, and the valve may be usable for some time.

Ti, on the other hand, is a lot of things, but one that it isn't is hard. Not hard enough to be a valve face, at least, and no treatment process exists that will make it that hard without leaving it brittle. So, it is coated with a variant of titanium nitride. TiN is considered a ceramic, and is off the Rockwell C scale at somewhere over 88. The downside is that for several reasons, this coating cannot be applied any thicker than .0002 or .0003". If and when it finally wears through, the valves sink almost immediately, and are soon unserviceable, and even dangerous.

But one takes no longer to wear out than the other, really. However, if I had any year 426 in need of a valve replacement, I would use the steel valves and springs from a 2000 model in my bike just because of the price.




 
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