Cling

I haven't actually removed the actual shim yet, just the cap that holds the shim. but, there are no numbers on top of the shim so I am assuming that it is either beneath it or I need to measure it with a micrometer.

GEORGE_JET

According to the manual, the numbers should be facing down. The reason I asked, was because I was trying to figure out why this valve seat might have worn as much as it has. When you get ready to measure it, please keep track of which way is up (ie a sharpie mark would help). also check if the top of the shim is concave, convex, or flat.

As far as measuring the shim, you could just use a decent pair of calipers (dial, or digital). A caliper can accurately measure down to the .001 inch, which is enough for what you need. Micrometers are cabable accuratly measuring another decimal point over. But you will find it easier to find someone with calipers.

Cling

I don't think the shim is the problem, something else must have happened, I measured the "bad" shim at 2.90mm, and I measured a "good" shim at 2.85mm... not much difference. Also, the "bad" valve had a pre-cut sliver of sheet metal cut out into a circle and placed under the shim, that piece of metal added 0.26mm of height to the valve, so I removed it, reinstalled the valve and everything, started the car but its the engine is still shaking like crazy, I rechecked compression and its much higher at around 150PSI (Optimum is 210~) but the engine is acting/sounding exactly the same, what a hassle....

GEORGE_JET

cam.doc

Here is a procedure for re-installing cams,
The shims will be different thicknesses. That is the whole idea behind adj the valve clearance. As far as a sliver of metal under the shim,,,well that sounds like someone was doing a hack job repair. The proper procedure is to measure valve clearance, remove the shim, measure the shim, calculate the required shim thickness, and then install the new shim.

It sounds like someone at some point someone attempted to check valve clearance and had a appiphany of a idea. And decided to use tin foil to adj thickness.

Cling

Ok yeah, I totally over torqued the cam bolts, hah. I took it apart again and re-torqued to spec and it sounds a lot better now. Though, I am still getting fairly low compression in cylinder #4 (140psi) so I will need to have the valves perfected as soon as I get a chance to open it back up and dig into it again. Thanks a ton George!

GEORGE_JET

Very bad idea to be driving around with the valves too tight. Right now it sounds like you need a valve adj, you could very well burn a valve, and then you will need to remove the head and spend a lot of money. And of course after a valve job you would then need to adj the valves.

mmatheny

I thought you said after you removed the shim you had compression in the 200s! If that is true, what is the clearance between the valve shank and the cam lobe (at it's lowest place)?

12340987

Where can you get bucket depressors for these engines? I have a honda 81 cb750 that uses the same 25mm shims. The whole top end looks quite similar. I'm hoping I could also use it to adjust the valves on my bike. I had one that turned out to be made of silver painted bronze or something so it didn't work for very long.
They only place I've found reasonable prices for shims is ebay, anyone have another source?