Shim Inquiry For Those In The Know

[chiefsfan.58]

Hello everyone, I just got to 243 miles on my bike and figured I had better do my "after break-in" valve clearance check. I thought that the intakes would be the ones out of spec if anything was at all, but much to my surpise, they were within tolerance. My main question is: Has anybody been within spec and still went down a shim shize? Please don't think I am stupid for asking why. I ask because although the intake clearances are "ok", they are at the very bottom of the tolerance. I would like them to be in the mid to high range of the tolerance due to the fact that as these components wear, the clearances get tighter. Has anyone done this or known of someone that did it and was still in spec?

BTW, my exhaust valves were about .002 in. out of spec at .006 in. I was surprised at this because from most of the reading I have done, the intakes are usually the ones requiring more frequent adjustment....

Thanks in advance for your help guys.

peace

[dominator426]

You're better on the 'tight' side as factory set since the clearance tends to increase with cam and lifter wear. Now at 7000 miles on my 2002 426, this is the 1st time I need an adjustment. (middle intake at 0.16mm-spec: 0.10-0.15mm)

[chiefsfan.58]

Hey dominator, the tolerances actually decrease as the parts wear. If you have a clearance that is above the tolerance, I would guess that you have something else going wrong other than normal wear. I just did a broader search for valve adjusting in the 450 forum and after reading so many things that my eyes hurt, I have decided that I am gonna go down to the next shim size and then recheck to see just how much of a difference each .05mm makes....... I am used to measuring with inches and this whole metric stuff is just making my brain ache! I guess I am gonna get out the calculator and do this the ol'fashioned way.......

wish me luck.

peace

[xcracer123]

Hey dominator, the tolerances actually decrease as the parts wear. If you have a clearance that is above the tolerance, I would guess that you have something else going wrong other than normal wear. I just did a broader search for valve adjusting in the 450 forum and after reading so many things that my eyes hurt, I have decided that I am gonna go down to the next shim size and then recheck to see just how much of a difference each .05mm makes....... I am used to measuring with inches and this whole metric stuff is just making my brain ache! I guess I am gonna get out the calculator and do this the ol'fashioned way.......

wish me luck.

peace

You are correct! The clearance does decrease over time due to valve seat wear and some minor stretching of the valve itself. You will be fine by decreasing the shim by one size.

[farkawi]

Metric measurements are pretty easy and shim sizes are all sized in mm. I broke down and bought a metric micrometer and shimset when I was racing a Kawasaki street bike. The magic number is 25.4. You can multiply and divide the numbers to go from metric to thousanths of inches and back again. Just make a diagram of your valve train and record the numbers. Be methodical and patient and it will be right the first time every time!

[clark4131]

I just did my '05 and I had one intake and one exhaust out of spec. Before you go and get shims, check the numbers on all of them as sometimes you can move them around and get things right that way. Also, I found in my bike that the OEM shims weren't necessarily in increments of 5mm. I had a 188 and a 179 in there along with two 180's and a 185. I had a second exhaust valve that was right on the cusp of too tight, so I put the 179 in there and it loosened it up just perfectly...SC

[chiefsfan.58]

Thanks for the replies guys........ I'm gonna see about moving them around but I have a feeling that I'm gonna be makin a trip to the dealahship in a few hours....... I hate to pay that much per shim but am going ridin again this weekend and have no time to waste! At worst I think I'm lookin at about $40 bones. Small price to pay for such a sweeeet machine.

BTW, this site rocks! I have turned anyone who's even pondering getting a 4 stroke or a product for the one they already have to this site to do a lil' bit of reading here before making any rash decisions!

peace

[Rip Wheeler]

You're better on the 'tight' side as factory set since the clearance tends to increase with cam and lifter wear. Now at 7000 miles on my 2002 426, this is the 1st time I need an adjustment. (middle intake at 0.16mm-spec: 0.10-0.15mm)

Actually, valve clearances decrease. The valve and seat angle are 1 degree different to seal fast, but as they wear together, the valve will lower itself into the head, thus, reducing clearances. If you start ending up with wider clearances, you probably have some abnormal cam wear. Once seated/matched, the clearances will take a long time to change. Probably due more from valve stem stretch at that point than wear, assumje all is wearing normally.

[dominator426]

Other WR owners have actually also reported increasing clearance in the middle intake. Mine has only gained 0.03mm (0.001") in 7000 miles. My 2 other intakes have only gained 0.01mm (0.0004"). One exhaust gained 0.01mm and the other is tighter by 0.01mm. I don't ride too hard and I do use Lucas Fuel Treatment in my gas which lubricates valve seats and creates a cushion for less wear and better sealing, and also lubricates upper cylinder...