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81' DOHC Valve size general question CB750C


CB750 New member
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Houston, TX
I'm building this bike with my nephew (his college transportation). I do build a LOT of DOHC I line 4 Yamaha and Kawasaki PWC motors but got a little turned around on the motor while pulling the valves, Springs etc). When I went to go throw her all back together I MAY have either the exhaust shims OR the intake shims 180 degrees off in the wrong order. I will check my clearance at TDC on all of them of course but I have a question on these valve heights.

On my PWCs, the lengths of the valves vary quite differently from one another on OEM heads...and the shim UNDER the buckets gets adjusted to compensate for that. However, when I threw these valves into my Mic they all measured out quite closely...probably just a few thou difference on them. Furthermore, when I pulled the shims out of the tops of the buckets I did not see any shim height stamp or embossed marking top of bottom to indicate the thickness varying on them. Were these older bikes actually set up with better matched engineering on the valve heights so that the shim height basically does not vary?...or did I just miss a marking somewhere on them?
Shim are in increments of .05mm or about .002" advised to set inlet and exhaust at .005", 0.127mm. shims are usually marked such as 295 300 305 increments of 5. I have come across several shims unmarked just have to measure these, hope this helps
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