[bones]

I just checked valve clearances on my '04 450r only to find my left intake gap to be out of whack. I can't fit even the thinnest feeler under the lobe. All other clearances where fine. I pulled the cam housing off and didn't find anything unusual - I thought maybe something was wedged between the spacer and the cam follower. I was under the impression that if the spacer needed to be adjusted, that a thicker spacer was likely needed, not a thinner one. The bike was running a bit hot but I attributed it to weather and tight single track - otherwise it was running fine. I was just doing routine maintenance. On the many other times I had checked before, all clearances were fine. Can valves seat themselves deeper to cause the gap to get smaller? WTF. Any feedback greatly appreciated.

[124]

On the many other times I had checked before, all clearances were fine. Can valves seat themselves deeper to cause the gap to get smaller? WTF. Any feedback greatly appreciated.

That's exactly what happens Bones. The valve starts to wallow in the seat. This disrupts the correct valve to seat angle and starts to wear the valve and the seat. It sits farther in the head and closes the valve clearance gap between the stem and the bucket. The shimming process is a reducing one; meaning the shim sizes will decrease in thickness to maintain the specified gap. Once you get to a 120 shim, it is completely out of adjustment and new valves are needed.

[bones]

Thanks, 124. I was hoping not to hear that, but thanks.

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Excellent post 124.
Now bones you have some choices to make. Some guys have started using TRX 450 stainless valves, others go the Kibblewhite route, some just replace everything with OEM components.
When my times up I'll be going with either the TRX 450 or Kibblewhite, either way I'll be using stainless steel valves. For the tiny bit of power or throttle response supposedly lost I'm not sweating it, these things have tons of power I can't use plus I've never heard of anyone who can feel the difference.
It's really important to replace everything when you do the job or you could wind up doing it twice, and that means valve seats either cut by someone with a great reputation, or some just go for a new head. The guides are very important too, they are expensive but if they aren't perfect you'll be kicking yourself for not replacing them as well.
This is why the AMA is looking at ways to bring two strokes back into the picture. Some guys like me who don't race every weekend don't mind a couple years between valve jobs, regular racers or those blessed with being able to ride year round may wel have to do this yearly, and no brands are exempt. Yamahas seem to go the longest , but they cost about 40% more to do the rebuild when you do have to. The KTM 525 Dirt Rider did the 200 hour tear down on needed valves before the 450X they did the same 200 hour on ,Kawasakis and Suzukis have some bottom end things go bad that Honda I've never heard of having.
So all these thumpers need some expensive work done on them from time to time, don't be misled by the myths.
If you don't do the job right your bike is worth practically nothing, if you do the job and do it right (I'd replace the piston too especially if it's the original)now your bike is ready to roll.
Keep all your receipts too. It'll sell for a good price if it's pretty and you can prove it's got a first rate top end.
Doug

[bones]

Thanks, dobent. I talked to the honda service manager near me who feels the original valves are better than the Kibblewhites since you don't have to put in such a heavy spring to make up for the extra weight of the valve. So, although the valves hold up better, you end up doing head damage from the force that the spring places on it. He states he does as much work on Kibblewhite/heavy spring issues as he does on stock valve re-do's, if not more. I don't know what to believe. I guess I'll have to pick one and go for it. Any advice on Wiseco pistons fs. Honda oem? I have a good Wiseco high compression piston but don't want to run race gas all the time. Will I smoke the piston (and do major engine damage) if I run 91 octane with a high compression piston?

[[email protected]]

Hey bones,
That service manager is not giving you the straight scoop bud, that's flat not true and it bugs me when people get misled like that.
I'd call Kibblewhite technical support and get their version.
First, lets look at what "head damage" is. If he means damaged seats that need cut,(he does) well you shouldn't really replace valves without cutting the seats anyway in my opinion.
I've never heard of any problem with Kibblewhites unless it's someone NOT running the heavier springs yet using the Kibblewhite valves anyway.
Wiseco makes great products, but if they tell you to use race gas or a 50/50 mix on that particular piston you'd better do so because you could get into a problem if not.
It'll tell you in the directions if it needs it or not, I'd go with whatever they say. Personally I'd never use a piston that needed race gas, to me it's a big hassle for little gain.
There are a lot of good options for you, but for someone to make up a story for why not to use someone elses product is not good business, neither is passing along hearsay when you're a Service Manager.
Doug

[124]

Bones - Sorry for the late response, I've been up north trail riding this last weekend.

So, although the valves hold up better, you end up doing head damage from the force that the spring places on it. He states he does as much work on Kibblewhite/heavy spring issues as he does on stock valve re-do's, if not more.

I chuckled a little when I read this. Really though...BS. Head damage (I think actually we all really mean valve seat damage), is caused when the valve makes incorrect physical contact with it. ANY valve will cause damage to the seat if it is mis-aligned or improperly adjusted, and makes contact, regardless of material. Ok, ok, maybe not rubber...but you get my point right? Stainless valves and springs have at least doubled the amount of time in between re-builds on every bike I've done or known to have it done. That's a fact.

I've had good luck with Wiseco pistons. I've never felt the need to run one with increased compression because of the need to race fuel. But their standard compression replacements are good imo.