09, 450 valve clearance.

[emrich-55]

I just bought an 09 yz450. I have talked to a few people that are saying that they are having to check and adjust there valves as much as every 15 hours. Just wondering how often other 450 riders have had to adjust there valve clearance. Thanks.

[grayracer513]

Two '06's with two and three years of time on them, never adjusted. My old '03 with 300+ hours, never adjusted. Checked but never adjusted.

[Dick Falcon]

damn gray!thats what i like to here!

[myoung]

I just had to change all my intake shims one size at 30 hours on my '09. The exhausts were both still good. I thought it would have been the other way around.

[Family Man]

My bike hasnt need a valve adjustment yet with huge load of hours on it.

[rjcook450]

85 hrs. on my 08 450, checked 3 times, never needed adjusted.

[rmcr250r]

Checked mine at 30hrs and they were fine. Maybe those people who are adjusting at 15hrs dont run airfilters:bonk:

[yz-dwg]

+/-350 hours on my '06, checked 3 times, no adjustment needed. Now I am wondering if I should look at my piston, still runs strong and doesnt use any oil

[myoung]

You guys that aren't adjusting your valves, are you leaving them if they are on the tight side of spec? Mine were all on the tight end, but still close to spec. Just rather have the room for wear.

[grayracer513]

Spec is .10-.15 for intakes and .20-.25 for exhausts, as you know. Yamaha deliberately builds them as close as possible to the minimum side of the spec because it's better for the engine, using shims in .01mm increments to accomplish this. Many of you have probably found shims such as 187's and 186's and wondered where they came from.

If an intake valve is at .10mm, it is within specification, and needs no adjustment. If it's at .095, it's out, and needs attention. That simple.

[husqy360]

my 06 have 150 and more then 50 with a paddle, still starts like new.

[mywifefarts]

I just replaced my cam chain on my '07 at 58 hours and valves were all within spec. Do any of you guys with tons of hours ride any serious motocross?

[mkporn]

I just had to change all my intake shims one size at 30 hours on my '09. The exhausts were both still good. I thought it would have been the other way around.

It is almost always going to start with the intake valves. They see that nice fine dirt that gets thru the filter and it acts as a lapping compound, wearing the hardened valve face which causes premature ware.....

Everyone remember Honda having a big issue with valves...... it's funny that they also had an issue with the air cleaner fit and the ring that bolts the air box together. seen alot with fine dust in the intake...and bad valves.?

[mkporn]

I just replaced my cam chain on my '07 at 58 hours and valves were all within spec. Do any of you guys with tons of hours ride any serious motocross?

if you are looking to get a review from someone that rides hard and would have the most issue, you might talk to a few people that ride dunes alot and are good riders. There is nothing more punishing if you ask me. Not only is the sand hard on equipment but the way you ride in sand is totally different than dirt. huge loads on the motor do to the traction in the sand (paddles) and the fact that you pretty much could put your throttle on a on/off switch cause you really don't need in between for the most part.....?

[mywifefarts]

Everyone remember Honda having a big issue with valves...... it's funny that they also had an issue with the air cleaner fit and the ring that bolts the air box together. seen alot with fine dust in the intake...and bad valves.?

That reallly is sad if that truely was a large contributing factor with the Honda valve issues.

[grayracer513]

I know that's been said about them, and that it has been a legitimate problem, but I'm not convinced that it was all of it. Lord knows I've seen a number of poorly serviced YZF air filters on really high hour bikes.

The point about riding in sand is a good one though, especially without a paddle. In that circumstance, the engine will spend LONG periods at full throttle on a regular basis.

[mkporn]

I know that's been said about them, and that it has been a legitimate problem, but I'm not convinced that it was all of it. Lord knows I've seen a number of poorly serviced YZF air filters on really high hour bikes.

The point about riding in sand is a good one though, especially without a paddle. In that circumstance, the engine will spend LONG periods at full throttle on a regular basis.

Sorry guys, I didn't mean to make it sound like that was the whole deal. I actually chalk the honda valve issue up to the perfect storm. I think it was a maint issue, air box issue, rider style issue and a hole crap load of people jumping to something they knew very little about.

[grayracer513]

I think you're right, and of course, no one could say the air filter situation was a good thing at all. I'm just saying that even without that there would still have been a difference. Pretty much what you just said.

[jratcliffe3]

I think honda made a change about 05/06 that improved things. I think this was to the valve coating material. I had an 03, which I had to change the intakes on, and an 07 on which the valves never moved, and it had about 100 hrs on it.

Both were otherwised maintained the same in terms of filters and oil changes.

Another feature that can affect valve wear is the speed at which they close (cam profile). If the cam profile means the valve closes 95% of the way quickly, then the last 5% relatively gently, it will cause less wear to the valves than one which pretty much allows the valve back in as quickly as the spring will pull it.

[grayracer513]

Another feature that can affect valve wear is the speed at which they close (cam profile). If the cam profile means the valve closes 95% of the way quickly, then the last 5% relatively gently, it will cause less wear to the valves than one which pretty much allows the valve back in as quickly as the spring will pull it.

That feature is called a "quieting ramp", and it is indeed an important feature. Some aftermarket cams don't dedicate as much effort to it as the OEM's do, either.