Valve Adjustment on the Bench

Through a combination of laziness and stupidity, while installing a Heli Coil in a stipped cam cover bolt hole, I destroyed my head. I got a replacement and I was wondering if I could do the valve adjustment on the workbench. I have a little down time waiting for parts and I thought doing this would not only keep me busy, but speed up the process as well. Has anyone tried this before? Did it work? The new head has no shims or buckets so I don't even have a rough starting point and this would be a great help if it will work. Any thoughts? This is for my 650, by the way, so the cams must come out for every shim change.

Post edited by: madderkaw, at: 2008/02/17 11:31

There are two ways you can do this with 650 buckets. You can do it one valve at a time but you would have to remove the cams twice for every adjustment. Or you can get eight 2mm shims, install them under the buckets, and measure all the gaps at the same time while just rotating the tightened down cams by hand. Write down all the measurements and than you can replace each 2mm shim with the correct one.

I don't think I have 8 2mm shims, but I might have 8 of the same size. I guess this would work on the same principle?

As long as those eight shims give you some clearance to measure, you'll be able to figure it out.

As long as they are all smaller than the gaps require. they do not even all have to be the same size, as long as you know what size is where so you can do the math. The most important thing to remember is that they ALL must be smaller than required for each valve.

Actually you will only need 4 shims of the same size as you do ONE CAM AT A TIME or you risk bending valves - install shims, buckets and ONE cam, measure the clearances and write them down. REMOVE the cam you already measured and repeat the procedure for the other cam. Then it´s just a matter of calculating what size shims you need to be within spec.

And oh yeah, don´t forget to sit the head on a couple of wooden blocks or whatever, when you install/rotate the cam the valves will stick out below the lower surface of the head.



Post edited by: OnkelB, at: 2008/02/17 14:10

Something that helped me 'do the math' when I adjusted my valve clearances was the chart in the FSM. If you have one of those, just use the chart to figure out exactly which shim you need.

Thanks eveyone. Sounds like a plan. I'll have at it tomorrow since I have the day off.

You need a good starting point, but double check after the head is installed. They may change a little once the head gets bolted down.

Sid pogue would never shim a head for me unless it was torqued down on the motor way back when,not sure if he ever changed his ways .but i remember atleast 3 heads he did for me way back when he always said things changed when you torque the head down;)

Bench shimming will get you close but never count on them being right after you have the head torqued on. ALWAYS recheck your work after the head is installed. Torqueing the head bolts can "move" the head a little and that's all it takes. Better safe than sorry.

I'm not trying to hijack the thread, but have a question on the acceptable range for valve clearances on a '81 KZ650 (H) CSR. It has the air injector system and automatically adjusting cam chain tensioner, for what its worth. The bike is basically in great shape (with under 15K miles), and while finishing things up this Winter, in preparation for Spring, I wanted to give it a thorough going over.

I read WiredGeorge's write up on valve adjustments a few times, and read ELR658's comments on the BTK forum, as well as the posts on this forum. I have a Clymer manual, and can't seem to find a straight answer on what the acceptable clearances are for my bike. I have the original owners manual, which is no help and tells me to take it to the dealer to be checked. The Clymer manual only lists .15 mm for a clearance, in several places. I've found 0.8-.18mm elsewhere, and .10-.15 yet another place. I want to keep these on the looser side, but don't know what the range should really be.

My current clearances, on the bike with the head bolts properly torqued, are:
1-I:.152mm, E:.0120mm, 2-I:.127mm E:.150mm 3-I:.120mm E:.127mm 4-I:.175mm E:.102mm
Can anyone tell me if these are OK? Changing any shims, other than to #4 cylinder, would put the clearances over the .150mm target in the manual. On #4, the intake could be brought down to .125mm and the exhaust up to .152mm, but is this worth the trouble right now?

I'd have to pull the carbs to get the tensioner off to loosen the cam chain, to remove the cams to get at the under bucket shims. The tach pinion would also have to be pulled when the exhaust cam comes out. I don't mind doing this, and the local Kawasaki dealer will do $3 shim exchanges, but I'd rather hold off on pulling everything, if I can reasonably wait another year. I have a new valve cover gasket and cam end plugs, but could save those for later, if pulling the cams can wait. I have another set of carbs that I want to rebuild and new intakes, but those won't be done for awhile. I anticipate that I may end up with some air leaks if I pull the current rack of carbs now to get to the cam chain tensioner, and would rather wait til next year and pop on the rebuilt rack and synch them then.

Sorry about being so long winded. Am I OK as is, or should I expend the effort now to get these at or above .15mm? What is the acceptable range for an '81 650?