Does my valves need shimed?

I just got done awhile ago checking my valve clearence and here is what I came up with.

Intake 1 is the one Iam calling at the far right (kickstarter side) and intake 3 is on the far left (next to the camchain).

Intake 1= The 0.10mm feller was pretty tite but went under the lobe. The 9mm feeler for some reason wouldnt go under but the 8mm was way to easy.

Intake 2= The 0.10mm feeler was easy and th .15mm had the drag feel to it

Intake 3= The .10mm was way easy and the .15 had the drag feel to it.

Exaust 1 is the one Iam calling on the far right (kickstarter side) and 2 is on the left (camchain side)

Exaust 1= The .20mm had drag to it and the .25mm wouldnt go under

Exaust 2= The .20mm was pretty tite wouldnt hardly go under but you could get the feeler under, just had to push on it kinda hard.

Now with these measurements do you all think I need a shim job?

The last time it was ever shimed was when I had the top end done for the first time at 50.2 hours. My buddy that owns the yamaha shop here and is the mechanic there done it.

I now have 80.1 hours on it now and was wondering if I need the valves shimed. It has 30 more hours on it since I had the top end rebuilt.

My bike is a 2006 yz 450f yamaha

Intake 1, and both exhausts need smaller shims. One increment will be fine. Be careful when checking them with the feeler gauges its possible to push the bucket down if you force the feeler to hard. There should be just the slightest bit of resistance. Always double check your valve clearances after you install the cams. Check your valves every 25-30hrs.


So I dont need to do any shimming to the others? Intake 2 and 3 is ok at .15mm (assuming the valves will get tighter)

I might add that the exaust 1 might had been a little tite but not much.

yea 2 and 3 will be ok since 99% of the time the valves tighten up. I check my valves every 20 hours for piece of mind.:thumbsup:

I talked with my buddy at the Yamaha shop today and told him what the valve measured.

I told him the two exaust valves seemed to be feel rather tite and the #1 Intake valve felt a little tite.

He told me the feeler gauges were sometimes kinda tough to get under the lobes sometimes because when they were made the ends had a lip on them.

He said as long as I could gethe 0.10mm under the Intakes and the 0.20mm under the exaust lobes then it should be alright,cause if I were to shim down a size smaller they would be to loose.

Said once you get the feeler under the lobes and the sliding motion felt good and not extremly tite they should do.

Iam going to go check again here in a minute since i still have the cover loose.

Hmm. ive never heard of feeler gauges having a burr on the end of them. They are precision tools,such imperfections would make them useless. If your valves are at .10mm or .20mm i would definetely shim down because if you dont your valves will be out of spec in the next hour or two if riding. if you shim down with them at.10mm or .20mm you will still be in spec. It will be on the loose side of spec, but thats what you want,since they tighten up anyways. Hope this helped. feel free to ask more ??'s

Edit: i just mic'ed out my feeler gauges on the tip and they all are exact. Not sure where your buddy got that idea from. The reason they are hard to get under the lobes is because of the location of the cam caps, and the angle you have to insert the feelers at. i curl the tips of the feeler gauges i use for valve adjustments. Makes it so much easier:thumbsup:

Hmm. ive never heard of feeler gauges having a burr on the end of them. They are precision tools,such imperfections would make them useless.
The $4 feeler gauge sets at the auto parts stores are usually fairly trustworthy (the ones I've mic'd have been), but frequently have edges that could be finished better. A sharpening stone will fix that.

Well yea, i see what your sayin. some brands of feelers probably do have some imperfections. personally i have a craftsman set that is ok, but i also have some snap-on slim feeler gauges, and they have a rounded edge the whole perimeter of the feeler. they make it extra easy on the yz thumpers

That's really one of the few things that separates the cheaper ones from the better ones; whether the edges are finished or just "as stamped".

Iam going riding tomorrow and I usually get in about 1.6 hours on the meter at the track. When I get back home I'll clean it up and check the clearence again and take it to him and let him check it and see what he says.

If he checks it he will probally say it is a little tite. I will get the shims since since they will need shimed sometime.

It has been 30.1 hours since the new top end has been put in, Do you all think I should go ahead and at least put rings in?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now