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OnTheEdge

New valves or pad adjustment???

10 posts in this topic

I was having problems starting my '03 450 and I figured I'd check the valves.

The exhaust valves are ok (in spec), but I can't get the spec (.10 mm) feeler gauge between the cam and the lifter. This took me a little by surprise as I was expecting the gap to be larger than spec figuring on some wear. It seems that they may stretch as well?

Given that information (and maybe that's not enough), should I do a valve replacement or is it feasible to put smaller shims/pads in to get it back in spec? If the recommended course of action is new valves, OEM (Ti) or Stainless??? Also, any tips on where to get them would be great too!

Any help would be greatly appreciated....

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They don't stretch, but the wear takes place between the valve face and the valve seat, which causes the valve to move higher in the head, closing the valve clearance up.

In deciding whether to shim or replace, you need to know how much wear has taken place. If the valve needs a shim .10mm or more smaller than the ones originally installed, then it is almost always an indication that the hard coating on the valve is worn through, and the valve must be replaced.

Done correctly, there is no better way to replace these valves than with OEM titanium. But know that the job must be done right. The guides must be in good condition, and the seats must be finished perfectly to match the valves (they cannot be lapped). Choose a competent shop to do the work.

Using stainless instead does not really provide an advantage in longevity, although it can be done cheaper than Ti. Kibblewhite makes high grade SS valves that are somewhat less expensive than OEM Ti. SS valves are almost twice as heavy, however, and the problem with KW is that their spring kit uses Ti retainers to offset the extra valve weight, and at $200+ for the kit, it pretty much wipes out the savings from using their valves.

Faction MX makes one piece hard coated SS valves, and also sells springs for them at a reasonable price. The quality of these valves is not known to me first hand, but I haven't heard anything bad about them. One could either use all Faction MX stuff, or KW valves with the FMX springs and save a buck. Whether it ends up being worth it in the long run would remain to be seen.

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Thanks gray! kinda what I figured but just needed something to backup what I was thinking....

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[Done correctly, there is no better way to replace these valves than with OEM titanium. But know that the job must be done right. The guides must be in good condition, and the valvesseats must be finished perfectly to match the (they cannot be lapped). Choose a competent shop to do the work.

How do you "finish" the valve seats without lapping them?

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ok. Did a little searching and answered my own question. Let me pose this question. If you replace the valves before they are desperatly needed will the valve seats generally not need to be re finished? Other words if they pass a leak test am I good?

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The valve seats always need to be refinished if the valve is refinished or replaced. Always. If you get to them before they become an impending disaster, the seats in most YZF's will only need a very light touch-up.

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The valve seats always need to be refinished if the valve is refinished or replaced. Always. If you get to them before they become an impending disaster, the seats in most YZF's will only need a very light touch-up.

Can a guy in his garage refinish them or is this a machine shop only thing?

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How long does it take a shop to due the job, approximately of course? Trying to figure cost. Is it an easy job with a seat cutter/grinder? I probably wouldn't trust a random shop do the work.

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How long does it take a shop to due the job, approximately of course? Trying to figure cost. Is it an easy job with a seat cutter/grinder? I probably wouldn't trust a random shop do the work.

A shop here in Vegas cut the seats in my 250F in about an hour and charged $20 a valve.

I hear the machine is pretty expensive and not all shops have them. Two other local shops said they had to ship the valves and head, but right before I had my parts shipped off, I heard of this other place. They did a super job.

Good luck.

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