1978 GS750 Broken Valve Shim

[Steve]

I would REALLY hesitate putting one in there. Yeah, it sounds great "for measuring purposes", but it will be SO easy to forget to take it out. Even worse would be if you used more than one. Theh 2.30 should be great for "measuring", don't worry about the others. When you get your "measuring" shim installed, measure the clearance, enter that value into the spreadsheet you just received, it will give you the value of the shim you should have. Please note that you still have to think a bit. If the new shim will leave you at the very bottom of the clearance range, consider a shim one size thinner. Yes, it might leave you just over the specified clearance, but many of us will go to 0.10mm for our upper clearance.

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[alkswheetinjur]

Today I was able to get my measurements with my 2.30 shim and with a little math (2.30 + feeler measurement - .076 = new shim size) which I was able to confirm with Steve's handy spreadsheet. And now for (hopefully) my final question on this topic. All of my exhaust shims I need are in the 2.70 to 2.75 range but my intakes are all smaller at 2.40 to 2.55. Is this something I should be worried about?

[Steve]

No worries. Just change what you need to change. When you have all the shims replaced, spin the engine for 5 or 10 seconds with the starter to make sure they are all seated, then check your clearances again. If they are all in the upper end of the clearance range, you might not have to change anything the next time around. Anything less than half, I would have a shim ready. That "next time" might be the last time you have to change a shim for a while, but you still need to check them every so often.

Looking at your math again, what was the 0.076?

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[alkswheetinjur]

.003 in = 0.0762 mm

[jdion81]

spin the engine for 5 or 10 seconds with the starter to make sure they are all seated, then check your clearances again.

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Ok, a question on spinning the engine while checking the clearances. Would you put the valve cover on before running the starter? I got my clearances dialed in, while the engine was on the bench then due to a timing chain tensioner issue decided to pull the valve cover after the engine was put in the frame (and verified that the engine ran). When I pulled the cover there was oil in parts of the head under the cams. Wouldn't running the starter throw oil all over?

[Nessism]

There may be some oil dribble but it won't go flying.

[Steve]

True, there is flow, but no fling.

You do have to watch, though. There are pockets that hold oil. While the engine is spinning, they will fill. Some will empty toward the center of the engine readily enough, others might fill and try to go over the edge.

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[alkswheetinjur]

Just got everything back together and I can now bump the kick start by hand (on the bench) and it fires right up! Thanks for the help and patience everybody. This will be waaay easier next time around.