valve clearance check with unusal result

steell wrote:

bountyhunter wrote:

steell wrote:

Take the shims out (can be done with shim removal tool)

Umm, nope, no such tool will work on a KZ750L3, it's a 750 four and the shims are under the buckets.

Oh, it's one of those......

Yep, and it's also one of those that rotate in the clockwise direction

The twins are the only ones that rotate counter clockwise (as far as I know anyway).

Actually, it probably doesn't matter which way the thing is turned as long as the chain tension is held. I noticed it only mattered if I turned it and then turned it the other direction to "center up" the cam lobe over the lifter. Drove me nuts for a while because two of the readings would change when I did that. Not a big change, enough to notice.

Back on topic

I have been giving this problem a lot of thought, and I can't figure out any possible way for the clearance to close up by retorquing the cam caps. For that to happen, the cam has to be moved closer to the valves.

And that gives rise to a new thought. In order to move the cam closer to the valves, some aluminum is going to be displaced, or had already been displaced. So I suggest removing the exhaust cam and taking a real good look at the caps and the bottom bearing surface. If the cam has moved, it's going to be fairly obvious.

If it were me, I'd re-check the valve clearances first, I do make a mistake occasionally

Likewise, I don't think it is possible to change the actual clearances by torquing the caps either.

That's why I suggested rechecking them and making sure the cam chain is tight by turning in one direction.

With the valve cover off, the cam chain will not be tight as it is when running (at least mine isn't). The cam journal NOMINAL clearance on mine is about .0015 - .003", with service limit of .006". That means a camshaft (even with nominal clearances) can have enough up/down play to shift valve readings a thou or two. I saw exactly that on mine, even though all the journals plastigauged within nominal limits.

Mine only did it on the intake cam never saw it on the exhaust cam. I theorize it's because with the CCW riotation mine has, the intake cam has the chain pulling straight down when the crank is turned. That would pull the cam down fully, releasing it slightly would let it ride up a bit.

If this L3 engine has CW rotation, the exhaust cam would be the one with the chain pulling straight down so tensioning the cam chain would pull that cam up and down.

It's the only way I know of to make clearance readings shift without changing shims.

Really the only things that effect clearance is the cam and shims. Should read exactly the same if you turn the engine forward or backward and I can't imagine camshaft cap torque making any measurable difference. I don't think it's ever a good idea to turn the engine reverse direction though. When you fool with the cams at all always turn the engine over several turns to make sure everything is all seated in place then recheck clearance. Maybe it's this simple? All that makes sense to me.

RonKZ650 wrote:

Really the only things that effect clearance is the cam and shims. Should read exactly the same if you turn the engine forward or backward

That's why it took me so long to believe it when mine were doing it, and they were driving me nuts. But, there is vertical play in the camshaft and when one cam is pointing away from the lifter, some other cam on that shaft is depressing a valve (at least partially) and that spring load tends to push the camshaft upwards away from the head. I had two valve clearances showing shift when I would pull the cam past and then turn it back to center it because that let the slack out of the chain and let the camshaft raise up. I recall on one is was shifting about .001" and the other was shifting .002" (going from .003" to .005" ).

It took me a while to figure out why it was shifting. As long as I turned the chain in only one direction and did not reverse, it never did it and always gave the same readings (and the lowest readings for clearance).