we were told that they needed to be adjusted after 10 hours of riding and then after that you wont need to mess with it again

 

Looks like the CRF450 has the shim under bucket for the intake like you said, but it looks like one of the exhaust is a screw and lock nut, the other one, big question. But I can't see how a shim under is working with the exhast valves.

 

I have a 02' Foreman ES. After about 800 miles it started making a clattering noise. So I adjusted the valves and haven't had a problem with it since. This wheeler has been though extremely harsh riding conditions.

 

Owners manual says every 200 hrs. Not near often enough in my opinion! I will adjust them after the bike is well broken in ~20 hrs., then every 50 hrs. or so after that.

 

So, has anyone figured out how to adjust the exhaust valves yet?

 

I adjusted the exhaust the same way as the intake. I'm not a honda tech, hell I just got a service manual a couple days ago. I can't find it at the moment. But let me know if you want and I'll find it and tell you what it says. So I'm not telling you the "right" way necessarily. I'm just telling how I did it.[img]i/expressions/face-icon-small-smile.gif[/img]

 

So, were there shiny buckets over the exhaust valves just like the intake? Maybe they just took them out of the pictures above, for display purposes, because they LOOK like shim-under-bucket design, only witout the buckets...

I'm really curious, let us know when you find your manual! [img]i/expressions/face-icon-small-smile.gif[/img]

 

OK everybody. There are shim under buckets on the intake side, just like a Z400 engine, the ex. side has shims, but no buckets. The only lock nut style adjustment , is for the decompressor. You use a shim to adjust it. The have thickness on them, you use a thicker or thinner, depending on the reading.
It is extreme over killt o adjust shim style valves more than every 100hrs.
I did it before I put int he cam, after I put inthe cam, after first ride with cam. Its good to go for a while.

 

If there's no bucket, what holds the shims in place?

 

In answer to my own question:

The reason for the buckets is because the cam "rolls" over the valves, so you need a broad, smooth surface for the cam to ride on to reduce wear.

As for the exhaust valves, the rocker only "pushes" on the shim, and with the proper valve clearance, there isn't enough room for the shim to pop out of it's seat. In addition, the surface tension of the oil is what holds the shims in place.