Question about valve shims...

[jdion81]

I got the spreadsheet from you back in March, I think it was. Thank you for that! I am checking with the lobes pointing away from the head. As if the valve cover gasket were the reference point and the lobe was pointing at 90 degrees upward from the gasket surface. Either in that position or parallel to the gasket surface pointing away from the spark plugs.

[Steve]

Not quite correct.

Let's start with EX1 and EX2. Rotate the engine so EX1 is pointing FORWARD and EX2 is pointing UP.
With the cam in that position, without moving anything, measure BOTH, EX1 and EX2.
Using the 19mm nut on the right end of the crank, turn the crank 180 degrees (1/2 turn).
You will find that IN1 is pointing UP and IN2 is pointing REARWARD.
With the cam in that position, without moving anything, measure BOTH, IN1 and IN2.
Using the 19mm nut on the right end of the crank, turn the crank another 180 degrees.
You will now find that EX3 is pointing UP and EX4 is pointing FORWARD.
You guessed, it, with the cam in that position, without moving anything, measure BOTH, EX3 and EX4.
Using the 19mm nut on the right end of the crank, turn the crank a final 180 degrees.
You will now find that IN3 is pointing REARWARD and IN4 is pointing UP.
Yep, once again, with the cam in that position, without moving anything, measure BOTH, IN3 and IN4.

Is it really that important? YES!! The difference can be as much as 0.001". Does not sound like much, but when you consider that the entire clearance range is only 0.002", yes, it makes a difference.

Yes, you did get a copy of the spreadsheet. On 01 MAR 2017.
Could not remember that far back, and there have been another 31 sent out since then.
As of 31 DEC 2017, 1079 copies have been sent.

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[steve murdoch]

Thanks for taking the time to spell out the correct positioning, Steve.

[Steve]

It's all in the OEM manual.

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[jdion81]

ok, I'm confused. I am checking with the cams the way you described, I've got a 2.0 shim in place and entered that in the spreadsheet along with a clearance of .021 in. I get a recommended shim of 2.5 so I throw in what I have a 2.35 and now when I check i get 0 clearance.

[Nessism]

The thinnest Suzuki shim is 2.15. I think a 2.0 shim will set below the edge of the lip on the shim bucket. Regardless, you need to get closer to your actual shim size in order to proper calculate shim sizes.

[jdion81]

I got the 2mm shim from Ray.

Hrm, I don't know what I'm going to do I can only get a clearance on two of the valves. Seems that the 2mm is too thin to start with and I don't have anything else close enough to check from. I'll end up going broke buying shims from Ray just to get this set.

[Nessism]

What measurement do you get with the cam lobe pointed straight away from the bucket? Also, don't forget to rotate the engine a couple times after changing shims to assure they are seated.

[gsrick]

I know this will start an argument, but you can check four valves at a time. All the cam has to be is on the base circle, not necessarily pointing up. The base circle is more than 180 degrees. So if the cam lobes for the #1 cylinder are pointing outward to the gasket surface, TDC, you can do both intake and exhaust lobes for that cylinder and one on #2 and one on #3. These two cam lobes will be pointing up.

This example is not a GS engine, but that doesn't matter.

Rotate the engine 360 degrees so the #4 cylinder lobes are pointing outward to the gasket surface, TDC, and check both in and ex valves on #4 and the other ones on #2 and #3.

[Steve]

Rick, that method is what is pointed out in the 16-valve engines, but the 8-valve engines have a different procedure.

It's not enough to have the valve/bucket/shim on the base circle of the cam. You have to have BOTH valves on that side of that cam on the base circle, so the cam is not being pushed askew in the bearing. The only way to do that is to put each lobe at a 45° angle from the valve, which puts them pointing UP and away from the center of the engine (exhausts forward, intakes rearward).

There is a measurable difference in clearance if you don't do it correctly. Some have measured about 0.001" difference. Does not seem like much, but the full range is only 0.002", so you can be off by as much as the full allowable range. Also, keep in mind that the minimum clearance of 0.03mm is 0.0012". If your measurement is off by 0.001", the actual clearance might be too darn close to ZERO.

Thanks for the suggestion, but I'll stick with the manual on this one.

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[jdion81]

I wonder if my issue is how I am using the feeler gauges. I think I could do better with the bent style. It seems the head where the valve cover surface is may be interfering with my use of the straight gauges.

[Steve]

I use straight feelers all the time. I have thought about getting some bent ones, but haven't done it yet.

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[Ghostgs1]

Be sure you are using the Suzuki manual procedure. Type of feelers matters little. If a 2 mm shim still has zero clearance, you may need to replace seats, replace head or try trimming valve stems a bit. Know where you are before doing any of these things. Let me know if I can help.

[Sandy]

I use straight feelers all the time. I have thought about getting some bent ones, but haven't done it yet.

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I use the bent ones only because that's what I have. I have used both types but found it doesn't much matter either way. They're thin enough so they bend to shape easily.

[Steve]

I have noticed that space is a bit tighter on the 550s and 650, and thought a bent feeler might be better. However, in my own stable, I only have a couple of 850s, a 1000 and a Wing that has hydraulic lifters, so I don't even need to check clearances.

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