Better to adjust valves for max clearance?

The Genuine Kawasaki shop manual states a valve clearance of 0.10mm TO O.15mm for the kz1000 running STD cams.
NOT a specific number between the two (i.e. 0.12mm).
Therefore any figure from 0.10 mm TO 0.15mm will do the job.
Setting them to the wide end of the scale will produce no adverse affect but will extend the interval between required adjustments.
For tuned engines and performance cam applications the clearance can be as much as 0.20mm ( Recommended for Yoshimura ST cams ).
This is to allow for the extra heat expansion produced by increased power outputs.
In my 35 years of building, running and racing these engines both on the road and track ,setting the clearance to the wider end of the scale has not caused any noticeable increase in valve wear, cam lobe wear or seat recession over that of running them at the lower end.

zed1015 wrote: The Genuine Kawasaki shop manual states a valve clearance of 0.10mm TO O.15mm for the kz1000 running STD cams.
NOT a specific number between the two (i.e. 0.12mm).
Therefore any figure from 0.10 mm TO 0.15mm will do the job.
Setting them to the wide end of the scale will produce no adverse affect but will extend the interval between required adjustments.
For tuned engines and performance cam applications the clearance can be as much as 0.20mm ( Recommended for Yoshimura ST cams ).
This is to allow for the extra heat expansion produced by increased power outputs.
In my 35 years of building, running and racing these engines both on the road and track ,setting the clearance to the wider end of the scale has not caused any noticeable increase in valve wear, cam lobe wear or seat recession over that of running them at the lower end.

Not necessarily true. The bike in question is NOT aKZ1000 it is a 1990 Zephyr 550 B1. So the blanket statement that setting the clearance to the wide end of the scale "will extend the interval between required adjustments" doesn't necessarily apply. If, for example, I had followed that advice on my KZ650 I would have needed to re-adjust the valves as some of the clearances widened further - which they did.

I'm not suggesting that not being exactly in the middle of the specified range will hurt the engine (as long as the clearance is kept within the range), but not all motors follow the same pattern regarding valve clearances, so a blanket statement like that can be misleading. Ed

.

If your valve clearances widened between services It was not down to whatever valve clearances you were running.
There was either an error in the original measurements or abnormal wear of the cam lobe, it's bearing surface or extremely worn shims that had broken through the hardening.
It is an impossibility that the valve , shim and bucket assembly can increase in length with wear.
It doesn't matter whether it is a Zephyr, z650 , 750 , 400 , 900 or any other bucket and shim ohc arrangement.
The principal is the same for all.

I don't think so. They generally widen ever so slightly but sometimes some of the same ones also tighten ever so lightly (see link below). I measure very carefully using the instructions in the manual regarding lobe position. As far as cam lobe wear - the cams show no wear at all. I have always changed oil every 1,000 miles (massive overkill, I know) and have been using Mobil-1 synthetic 4T oil since it was made available. I've always used top-tier, premium fuel. (Possibly the higher octane affects the burn rate which may protect exhaust valves/seats? I have no idea.) . I'm very happy that the clearances don't change significantly and that I haven't needed to adjust them.

I wonder if the larger valves on the KZ1000 and KZ750-twin contribute to the widening of the clearances. It's possible that the smaller valves on the smaller 4 cylinder bikes don't pack the same wallop when they shut.

www.kzrider.com/forum/2-engine/595262-be...ance?start=20#643792

I only ever saw two valves where the gap widened very slightly and in both cases the valve seal had failed and was letting oil drain down through the valve seat. Over time it baked on a hardened coating of black residue that kept the valve from fully seating which showed up as a slight increase in measured gap. Also eventually lowered compression and required a valve job, but that's the only time I saw gaps increase..

As far as cam lobe wear - the cams show no wear at all.

same on mine. I also used plastigauge to check clearance on all the cam caps and they measured nominal after 75k miles which was pretty surprising. Mine has no can bearings, just hardened aluminum in the head. Works pretty well.

zed1015 wrote: setting the clearance to the wider end of the scale has not caused any noticeable increase in valve wear, cam lobe wear or seat recession over that of running them at the lower end.

That has not been my experience. The wear on the ones with wider gaps tended to catch up to the ones with smaller gaps, at least on the few times where I payed close attention.

Wear by the very definition of the term could never allow the clearance to get smaller only larger... Simple mechanics

ezrider714 wrote: Wear by the very definition of the term could never allow the clearance to get smaller only larger... Simple mechanics

Not true. Valves and valve seats have narrow surface cuts and the valve's action of closing under spring force bears on those surfaces and can gradually cause the valve to go slightly deeper into the head which reduces clearance at the cam lobe.

ezrider714 wrote: Wear by the very definition of the term could never allow the clearance to get smaller only larger... Simple mechanics

Wrong!
In this application, OHC , it is the valve seat and valve head that wears causing the valve to recede in to the head towards the cam thus closing up the shim to cam clearance.
Wear in this case under normal circumstances will always only cause the gap to get smaller .

I've just spent all weekend doing the valves on my '83 KZ550 ltd shafty, so this thread has been sort of a gospel-chapter, in an atheist-sort-of-way lol … But seriously - Loudhvx you've been such a tremendous help to me following your bounty of material on 550s. .. But staying on topic - This is the first time I've done a valve job, at ALL!!! I'm so thankful for Kop & the rest who have just drilled that through.

I had ONLY ONE valve in clearance, Intake # 3. EACH and every other one was either critically too tight, or - Get this, Intakes 1 & 4 had NO clearance. …. I'm about to get the valve cover back on and hopefully test drive my first KZ (out of 7 I've owned lol ) that will have proper valve timing! .. A nice thought: When the cams were off, I did a quick hiss-test with the air hose in each cylinder - Heard nothing from the intake / exhaust manifold, & nothing from the breather, so my fingers are crossed that she'll be 10x as great as she already is, later today.

I consider myself VERY lucky - Been driving for 1.5 years on this bike. … OK - SHIMS UNDER BUCKET. … While Loudhvx you mentioned that the noise is coming from the 'cam' itself, hitting the bucket like a hammer - I realized, while reading your post - It's not that. It's the fact that the BUCKETS are actually flying upward from the force of the springs, and thus, striking the cam probably somewhere on the side. .. So, they're already hitting that cam at an 'unsmooth' position, just when they're being hurled upward at (how fast???), once the cam slips past and now they're rocketed by the full-force of those springs back into the cosmos!!!!

I mean, it's happening all in such a fast moment of time, but that clatter - After actually handling these buckets for the first time, feeling their mass, feeling how they slide out of the valve galleys, I totally suspect that there's a whole other type of impact going on, that Kawasaki probably took into account with the mass of those buckets, and the spring tension, etc - But they're hitting, and they're not necessarily hitting when the cam's at its smoothest sloped contour. All regardless of distance - In fact, I hypothesize that they're coming up so fast, they hit the heel (or equivalent arc) of the cam, and the oil-sleeve they're seated-in keeps them from bouncing back (absorbs the momentum), and allows the cam to gracefully hurl that mother back down the valve-channel the way the KawGods originally intended, each and every time.

I agree with Mission. I had bad seals. I set the valves and it ran fine. When I went to do a valve job, (new valves,seals and springs) I found all the exhaust valves were sitting on carbon. They had a good seal but when I cleaned them, I lost adjustment even though I have new valves. That little voice I never listen to said, (tip the valves) but noooo, I put it together and have 210 to 220 shims in there now. I'm going to buy the tipping jig and do it this time as I install my long a waited 10.25/1 pistons.
Gotta listen to that voice. :whistle:
Steve