valves and shims

[Guest]

i am checking the valve clearances on my "77" 750 and there is absolutely no clearance between the shim and lobe, the smallest feeler i have is .04mm, i even tried a rolling paper would not slide in there. am i correct in assuming that the shim and lobe should not be touching? i followed all instructions on the basscliff site as far as the lobe positions go.

[Steve]

You are correct, they should not be touching, but your smallest feeler is larger than the minimum, so you still don't know for sure.

Question: you say you followed instructions for the cam positions. When you lined up the lobe position to check #1 exhaust, did you change anything before checking #2 exhaust?

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[maddoghoek]

well, i checked all of them in about every position possible. i have yet to pull any shims out, waiting on a tool. the reason i am asking is im wondering if it could be a sign of a bigger problem if they are touching

[tkent02]

It could be a sign that if they were touching the valves could be burned. Hopefully you caught it in time.

[Steve]

well, i checked all of them in about every position possible.

I asked because it is a very common mistake. When the lobes are aligned to check EX1, they are also aligned to check EX2. That's right, you don't move the crank, you check two valve clearances at the same lobe setting. Then you rotate the crank 180 degrees, check BOTH IN1 and IN2. Rotate the crank another 180 degrees, check BOTH EX3 and EX4. Rotate the crank a final 180 degrees, check BOTH IN3 and IN4.

While you are waiting for "the tool", did you happen to see the "zip-tie supplement"? Some of us prefer that method of holding the valves open, rather than risking the valve slamming shut when "the tool" slips off the side of the bucket.

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[Ghostgs1]

When the cam is not engaging the shim, can you rotate the shim and bucket? If you can you are probably in good shape valve wise, since there must be some clearance there. You likely can get back in spec by dropping one shim size. If you can't turn them, you may still be okay if they haven't been that way for a long time. Probably two size drop will do it, unless they are burned. Ray

[maddoghoek]

thanx Ray, they all rotate when not engaged, i have no idea how long they have been tight like that. only had the bike for a month, only paid 700bux for it, only ridden it for bout 6hrs before it started running kinda rough...waiting on a tool orings and such

[Steve]

When the cam is not engaging the shim, can you rotate the shim and bucket? If you can you are probably in good shape valve wise, since there must be some clearance there.

thanx Ray, they all rotate when not engaged, ...

I used to think that, too, but I have done a couple of valve checks on others' bikes and found that the buckets can be rotated even when it took THREE shim sizes to get into spec.

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[Ghostgs1]

Steve, Was it easy to rotate the buckets when it required 3 size drops? As in using your finger tips or did it mean using a tool and lean on it? A lot of folks have picked up shims from me following this quick rule of thumb and it usually works. Not being critical, just curious. Ray

[Nessism]

The clearance reduces with mileage on shim and bucket GS engines. A LOT of people never adjust the valves and eventually the clearance goes away and the valves burn. Hopefully you didn't damage the engine too much with your recent joyriding.

Best to take an inventory of what shims you have currently installed. Remove each shim in turn and write down the number, then reinstall it. Never turn over the engine with a missing shim. Once you have your inventory place an order at Z1 Enterprises or the Shim Club so you will be prepared.