Tappet Clearances below spec

[dubwicht]

I just checked the tappet clearances and 6 are less than .02 and I don't have a .01 feeler to check them. Could a mechanic be that incompetent or am I missing something. I checked and rechecked several times. The other two were at .04 and in spec.

 

[Nessism]

That is why it's important to check valve clearance! As the engine accumulates mileage, the valve clearance goes DOWN, never UP. And if neglected, all the clearance will go away, and then the valves hang open and burn.

I suggest pulling all the shims out, and taking inventory of the size. Then order shims at least two steps smaller, for each valve. Sometimes you can move shims from one valve to another, so you may not need to buy as many as you may think. Oh, and never turn the engine out with a shim removed. Remove one at a time, write down clearance and size, then reinstall before moving to the next.

Last thing, I'd move any valve measuring below .05mm to that level or higher. Suzuki says .03-.08mm, but you can safely move that range higher, up to .12mm. Kawasaki KZ bikes run clearances up to .15mm, and they use the same shim above bucket arrangement as GS bikes.

 

[dubwicht]

Wow - thank you so much. I had tappet wear backwards, I thought that worn tappets would increase the gaps and require larger shims. You are saying that I may require smaller tappets? I need to understand this before I do anything else.

 

[dubwicht]

I am getting values between the available sizes including 2.83, 2.61, 2,77, 2.67, 2,62, Do I go up to the next size up and drop down 2? In other words 2.67 probably started as 2.70 - would two down be 2.60 or would I go down the next size and then two down from there to 2.55? Thanks. Doug

 

[Nessism]

Always error on MORE clearance, not less. Disregard Suzuki's specs, and move higher. Minimum .05mm, moving to .12mm as convenient.

 

[ironbiker]

If I had my last valve adjustment to do over again I'd run them all loose (.08-,.12 mm),less chance of burning one and longer time between adjustments,just saying.

 

[melchiro]

Wow - thank you so much. I had tappet wear backwards, I thought that worn tappets would increase the gaps and require larger shims. You are saying that I may require smaller tappets? I need to understand this before I do anything else.

When valves operate by opening & closing, they get "beat down" into the valve seat. Therefore, the valve clearances will always get "tighter", or less clearance. With proper oiling system, the cam lobes & shims are covered in oil, so those do not wear out much.

Does this make sense?

 

[Big T]

I am getting values between the available sizes including 2.83, 2.61, 2,77, 2.67, 2,62, Do I go up to the next size up and drop down 2? In other words 2.67 probably started as 2.70 - would two down be 2.60 or would I go down the next size and then two down from there to 2.55? Thanks. Doug

How far down you go in shim size is based upon how much clearance you measure with the current shim

If your 2.67 is at .02, go to 2.60 and rotate the cam a few times, then remeasure. Is it .09? If yes, then you're good. If it's .04, go to 2.55 and remeasure.

Yes, it's a process. It gets easier as you go along. Make sure your cam lobe is in the correct position when measuring.

A side note. The shims don't wear. Not all were manufa
​​​ctured in exact sizes. These are known as X shims. So the 2.67 is a 2.65X

 

[dubwicht]

I finally sorted it out after a couple days of messing around. I ordered the parts from Z1. The shims were only 5.75 each. Ebay robbers wanted $11.75 plus shipping. I reused 3 shims. Thank you so much for the help.