06 yz450f valve clearance readings?
Posted 13 March 2011 - 01:00 PM
Posted 13 March 2011 - 02:48 PM
Nope. They get smaller. The valve move up toward the cam as it closes, yes? Then when the seat or valve face wears, it moves up farther, and the clearance is smaller.
My question is don't the clearances get bigger as the valves wear? Is it something I should be concerned about or should I just ride it? It runs good...
Yes it is something to be concerned about. You need to adjust the 3 valves that are below specs, and then keep an eye on them for a while. Check the clearances every ride or two to determine if they are staying where you set them or they are steadily and quickly tightening. If they tighten more soon after you set them, you need new valves.
Posted 14 March 2011 - 07:26 AM
I just recently went through what you're going through, more or less. While changing a cam chain (motor had 60 hrs. at that time), I decided to check the valve clearances at that time. All my valves were at the "lower limit" of the tolerance zone, but more or less in spec.
I had some questions that got answered in this thread (please click here)....
One thing that came up (for me, anyway...) is how hard it is to duplicate the torque on the cam caps that they do at the factory.....
Now, before I did my cam chain, I "SEARCHed" as much as I could here, and read all I could about the job. I read, & re-read my manual. Per Grayracer513's recommendations, I torqued my cam caps to about 75 in./lbs.. I went up in 3 increments, using the tightening sequence in the manual. I checked my valve clearances again (no shim changes) after replacing the cam chain, and they all got about .0005" tighter!
One thing I didn't like was using my beam-type 3/8" drive torque wrench for this job. It's accurate, but honestly, my old eyes have a tough time reading the small radial increments on the scale. I also couldn't get it & my socket to physically fit between the head & frame for a couple of the cam cap bolts. So, I bought a CDI brand (owned by Snap-On) 1/4" drive micrometer clicker type torque wrench, checked it at the Calibration-Certification Dept. at work, and used it this past weekend...
I got all my shims I felt I needed, and "re-shimmed" my clearances this past weeekend. I ordered some Honda shims from here at the TT store, because you can get them in slightly smaller thickness increments than you can get the Yamaha shims. I first lightly tightened my cam caps down with with my thumbwheel ratchet, and checked my clearances. An .005" feeler gauge would go (on the intake side), and an .009" feeler went on the exhaust side. But even with taking what I felt were all the precautions I could, my clearances again tightened up a little. Now, an .004" feeeler goes in easily, but not an .005", on the intake side. On the exhaust, it was similar: an .008" gauge goes easily, but my .009" won't. I know I'm not overtightening these things, but that was my experience......
Anyway, I hope this helps ya some!
Posted 14 March 2011 - 12:41 PM
If you use assembly lube on the cams and such instead of engine oil, that can account for the half thousandth.
Hmmmm. Not to hijack powers450f's thread, I'll bet you're right. When I did the cam chain, I used some STP Oil Treatment I had for my assembly lube. I know you're somewhat biased against the STP, but it's worked fine for me for years And I had the valve lash tighten up bout a half a thousandth after final torquing the cam caps......
I found some Clevite assembly lube (Sorry Gray, but it simply looks & feels like red colored STP to me, hee hee ) at an auto parts store, and used that this past weekend. Same results. The clearances tightened up an average of .0005". But I see where the oil could account for some tightening. Again, what bewilders me is that I spun the engine over by hand a few times after finish torquing, sorta hoping to minimize that very effect........
Oh well.... It worked out well, and like the original poster, I'll check the lash again in 6-8 hrs. or so.
Posted 15 March 2011 - 08:46 AM
Posted 15 March 2011 - 09:02 AM
Posted 15 March 2011 - 09:12 AM