Better to adjust valves for max clearance?

Thanks for the compliments.

Remember, though, the bucket is following the cam profile for almost the entirety of the movement. If the clearance is too great, the spring and valve have already stopped moving from valve shutting. So there would be no further pressure on the bucket from the spring, and the bucket is already in contact with the cam at the moment the valve shuts. So other than a secondary bounce, there should be no primary "flying upward" and "striking". The bucket is already in contact with the cam at the moment the valve shuts.

But on the way to opening the valve, there is a large clearance then the cam suddenly makes contact (rather than gradually as designed).

This sudden closing of the valve could be noise. Normally, when the proper shim is in place, the valve would close gradually into it's seat. By having a shim too small, the valve shuts sooner, while on a faster-rate portion of the ramp. (And if the shim is too thick, the valve will close so gradually, it may not even close at all. That of course would be the most quiet condition.)

But either way, it's best to just follow the FSM instructions for this adjustment. And, it's normal for the ticking to be louder after an adjustment. Silent cams often mean the adjustment will be needed soon.

The opening and closing ramps on stock cams are very gradual. The lift does not get up to full speed untill the valve is open .100 inch. You would have to have clearances of .025 in. to do any damage or cause any unusual ware on the valves or seats. Setting the clearance to the max spec will never cause a problem and most of the time it will result in a smoother idle.
This was a subject of great discussion when I attended the advanced training school for BMW motorcycles.

Shim over lifters have a nasty habit of "spitting out shims". Be sure to stay within the adjustment range.
Steve

I've never worried about shim to lobe gaps of +.004"-.008" except a bit noisier. But I have been horrified on more then just a few of my lazy ass buddies bikes where I could not squeeze a .001" feeler gauge in to save a life!!

So neglected and misunderstood. :whistle:
Steve

Regardless of how gradual the ramps are, they start out at one rate and end at a rate of zero. So the rate changes as the valve nears closing. The earlier it closes, the faster the rate at which it closes. The faster it closes, the more bang there is when metal contacts metal. If Kawasaki wanted the valve lash bigger, it would have set the range bigger. The target is presumably the middle of the spec range.

In my experience, whenever I set the lash at the high end, it did not get me much more time between adjustments than when I set it to the middle. And it was way noisier. It did not affect idle one bit.

The Kawasaki service manual gives a range to maintain. .004 to .008 or what ever is the spec for a spacific model. It does not say anything about keep it in the middle of the range or a boogieman will come over to your house and put a MOJO on your bike. If Kawasaki says .004 to .008 than .008 is completely and totally safe. No additional ware, no long term problems of any kind.

John Wayne called him the "Booger man". :woohoo:
Steve

80B4 wrote: ... It does not say anything about keep it in the middle of the range or a boogieman will come over to your house and put a MOJO on your bike. ...

No it does not say anything about a boogieman, but if you follow their shim chart instructions exactly, it puts you as close to the middle as possible.

I realize people's old habits die hard, but in this case (KZ550) Kawasaki spells out exactly what to do. Aiming, and changing, for the high end means not following the manual.

I didn't say anything excessively bad was going to happen by having a valve at the widest lash. My argument is that changing shims and always aiming for the largest gap, even when already in spec, is not following the manual.

If the gap is at the widest, it should stay there, but if it is not, you should not change to get there. It is a long term (decades) effect. But many of us own these bikes for decades.

loudhvx +1

Also, keep in mind that valve clearance can and sometimes do change wider or narrower. I have seen this on my KZ650, but the change was very slight in either direction, and because my clearances were in the middle of the range the change didn't push the clearances outside the specified range. Ed

After my head was done by ape I bench shimmed it and it came right at .007 for 2 intakes and 2 at .0075 ..... they stayed right there only swapped after 600 miles the 2 at .007 switched to .0075 and vice versa ......... The ex I think were around .0055 and .065 on the bench and they stayed very close except for the #3 I remember that went from .0055 to .0035 and I opened it up to .0055 at the 600 mile check. I also checked em at 100 to be sure things were going right.

I really thought they would wear in and tighten up a little more than they did but I guess that's a mark of a quality vale job. Will check em again at 1.200 or 1,500 then go to every 3-4,000 miles. They seem to be quieter when cool and slightly louder on warm up but nothing to worry about which seems to be different from most of ya.

Buy a Vulcan 750 and you won't have to argue about how to check the lash... :woohoo: