No valve clearance?

[steppi]

Hello, I just bought a 79 xs11. It has 45k on it and runs great (2ond gear problem to fix but will tackle that this winter). I checked the valve clearance and I couldn't even slide the smalled feeler guague inbetween the cam and the shim. I looked on the forum and found alot of info on measureing shims. I have the manual as well. My question is how should i go about getting the correct shim thickness. Should I get a smaller shim to measure the gap, then use those numbers to get the correct shims? Is there a better way, or should I be thinking of pulling the head for an inspection?

Thanks

[skids]

Re: No valve clearance?

Yeah, get a smaller shim, but make it at least as much as would provide for the gap needed. In fact, I would probably shoot for the high end of the range.

Originally posted by steppi
Should I get a smaller shim to measure the gap, then use those numbers to get the correct shims? Is there a better way, or should I be thinking of pulling the head for an inspection?

Thanks

[TopCatGr58]

Hey Steppi,

You may want to do a compression or leak down test first. If you have very uneven levels, and retested with oil in the cylinders, and still have large variations in values, THEN you may want/ need to pull the head to do a valve job, cause you may have some that are burned, or heavily crusted from such close tolerances. When the engine heats up, parts expand, and so that non existent clearance could cause the valves to be staying open even further!

However, if your values are all within 10% of each other, and are good values, stock being 142 + 14 psi at sea level, then you are probably safe in just doing the shim job! If you have the tool, then you may first want to pull each shim, and record the thickness....should be printed/stamped on the underside of the shim, and then find the one that is the smallest, and hopefully you'll have one that is smaller than most of the others, swap it for each valve, and use it to measure the required/needed shim size. Being smaller than the rest, hopefully it will give you enough clearance to get a feeler gauge in there to get a measurement. You will still have trouble with the valve(s) that match the smallest sized shim you already have that is already too close.

Good Luck! T.C.

[trbig]

Not trying to be a butt here... but you did try to check that with a METRIC feeler that went down to at least .004 correct? If you are using a standard, then you will not be able to get the smallest feeler in there. (None of them that I found anyway) And just to make sure, you are measuring from the cam with the lobe pointed directly AWAY from the shim bucket?


Tod

[steppi]

Thanks for all the input here guys, it’s nice to know that there are people who have been there and done that and are willing to share there secrets. The feeler gauge I am using has both metric and standard stamped on it. The smallest feeler is marked with .0038 mm and .0015 in. I followed the instructions in the Clymer Manual with the cam lobe directly away from the shim. During the compression test I got values of 120psi +/- 5psi or so across the board. Only one had a compression of 95, with a bit of oil it was right up at 120. I haven’t done a leak down test yet, but with the above results it sounds like the valves aren’t sealing properly (resulting from years of not adjusting the valve clearance?) and I have ring problems on at least one cylinder. I think I better take off the head and look around. Any ideas?

Thanks

[skids]

I don't know about the history of your bike, but if it has been sitting around, the compression could come up in that one cylinder. Also, like TC said, tight clearances make for valves that stay open longer and it could conceivably affect compression. I would adjust the valves and run it for a few weeks to see if compression improves. Remember also that compression at elevations above seal level are naturally decreased accordingly, so just look at the differences between valves.

[steppi]

Thanks for the tips, I'll give it a try once my valve shim tool comes in.

[TopCatGr58]

Hey Steppi,

Aside from that one cylinder, those values don't sound too bad for that mileage. Also, with it sitting a while, both rust can build up inside the cylinders, and you could have some rings that are sticking. The increase with the oil isn't that bad of a sign. Like Skids said, better to fix the clearances, and then put some MMO in the oil, and run it without load at normal temps, for about 5-10 minutes, then drain oil and put fresh in, and run it for a few hundred miles, will help the rings to free up, and reseat IF there's some mild rust build up.

There was also a recent thread about cleaning off buildup of carbon from valves and seats WITHOUT taking the head off. May help to remove some carbon on the valve seat/sealing surface of the valve, which could further improve compression!

Also, check the tech tips, the valve tool sometimes doesn't work as it should, and a modification has to be done so that it will properly depress the valve bucket enough to allow you to remove the shim!
T.C.