Shim Inquiry For Those In The Know
Posted April 08, 2005 - 11:00 PM
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.
Posted April 09, 2005 - 12:40 AM
Posted April 09, 2005 - 01:25 AM
wish me luck.
Posted April 09, 2005 - 04:54 AM
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.
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.
Posted April 09, 2005 - 06:10 AM
Posted April 09, 2005 - 06:23 AM
Posted April 09, 2005 - 08:20 AM
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!
Posted April 09, 2005 - 11:37 AM
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.
Posted April 09, 2005 - 06:08 PM