Valve Adjustment Problem | GTAMotorcycle.com

Valve Adjustment Problem

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gmang35

Well-known member
2001 GSXR 600

I just did a valve adjustment a few days ago and everything was within spec except one side of the exhaust valve. One cam lobe I got the reading to spec and the other side on that same valve I couldn't get any feeler gauge in. I couldn't even get a feeler gauge down to 0.05mm in. I did the adjustment as if there was 0 measurement and changed the shim according to the chart. Once I was done and buttoned everything back up I still could not get any feeler gauge in.

Any ideas?
 
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Maybe run a compression test. If that cylinder has normal compression then there'd have to be a problem in the way you're measuring that valve.
 
Are you sure you had the cam in the right position? If the cam isnt in the right position, the lobe will be pressing down on the valve, preventing you from getting a feeler in there. Generally what I do is just rotate the engine separately for each valve, that way I dont have to dick around with the marking on the crank, just go by sight on the cam/valves.
 
I made sure the lobe of the cam was facing away from the valve. I'll do a compression check soon. I tried for quite a while to get the feeler gauge in. No matter how I tried to get it in, it just wouldn't go in. I tried at various angles and all. Every other valve exhaust and intake I had no issue with the feeler gauge.
 
Is there ANY point in the rotation of the camshaft that the cam lobe is NOT touching the valve bucket? If the cams are ALWAYS touching the buckets then you should see some wear on the back side of the cam lobe.
 
I'll have to take a closer look at the cam lobe when I have it apart again tomorrow. If there is wear on the cam lobe, what does that mean is happening?
 
First picture is where I can get the feeler gauge in no problem and it's within spec. The second picture is where I can't get the feeler gauge in for the life of me. Doesn't matter how small of feeler gauge I go.




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gmang35 said:
Just did the compression test. I got 140psi for all 4 cylinders.
Click to expand...

Actually I guess a leak down test would have been better but this is OK. I would conclude that the valve is in fact closing, and there is something wrong with your measurement. Especially since you made such a big change to the shim, the engine would have been running very poorly if the valve lash were so far off (burnt valve).

My best guess is there's something particular about the design of the cylinder head around that bucket that's obstructing the feeler gauge.
 
I've tried going from the left side and make the feeler more flat instead of at an angle and still no go. The bike runs fine now and before I changed the shim in that tappet. I changed the 138 shim to a 120 shim.

My calculation was (spec measurement - actual measurement observed) + old shim
(.2 - 0) + 1.38 = 1.18 I rounded up to a 1.20 shim (120)

I used 0 as my actual measurement observed since I couldn't get any feeler gauge in.
 
gmang35 said:
I've tried going from the left side and make the feeler more flat instead of at an angle and still no go. The bike runs fine now and before I changed the shim in that tappet. I changed the 138 shim to a 120 shim.

My calculation was (spec measurement - actual measurement observed) + old shim
(.2 - 0) + 1.38 = 1.18 I rounded up to a 1.20 shim (120)

I used 0 as my actual measurement observed since I couldn't get any feeler gauge in.
Click to expand...

I'm sure there's a better engine guy than me here who can figure this out, but until he speaks up this is what I figure: Either the valve adjustment was off spec before you adjusted it, or it's off now.

If it was off before, the valve would have stuck open and you would have had a lumpy, backfiring engine before adjusting it.

If it is off now, then everything would seem to run fine both before and after the adjustment, except now the valve would open late causing performance to suffer slightly and the cam or bucket would experience premature wear.
 
I don't know what to do now lol. Is the cam lobe in those pictures in the right spot for checking the clearance? I need to get a feeler in there somehow. `
 
gmang35 said:
I don't know what to do now lol. Is the cam lobe in those pictures in the right spot for checking the clearance? I need to get a feeler in there somehow. `
Click to expand...
Actually, looking at the second pic it kinda looks like the cams on that cylinder are pointing to the side instead of pointing up. That could certainly mess up the measurement.
 
I'll turn them straight up and see if that makes difference. Thanks a lot fastar1. I'll let you know what happens.
 
You have no idea what size shim is needed if you have zero clearance you need to go to smaller shims until you get clearance then you can calculate from there.
 
Depends how bad the head is make sure you are checking correctly first. Make sure the cam lobe is opposite the shim you are measuring.
 
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