Valve clearances and noise...quick question.

Hello again,

Well I retarded my timing and my engine sill sounds like a diesel or a VW bug engine with a lot of valve noise. Clack, Clack, Clack!

So I checked my valve clearances (after checking the torque of the cam caps)and one valve was at .09 mm, two valves were at .15mm and the remaining five were at .12mm.

So it appears I must reduce the clearances on 7 of the valves to get into the .5 to .10 range.

My question is, would the excessive clearances noted above result in the noise I am experiencing? Have I found my culprit?

Again, my bike is a 1976 KZ 900, bored to 1075cc with a MTC kit and .385 cams (Z2 grind).

Thanks again to Wired George and his awesome website - your instructions on how to check clearances helped me a lot. Also thanks to nads.com and duck...

Post edited by: Scoot Jockey, at: 2006/07/02 18:10

yeah if they are that far out on that many it would definately be noisy,hope thats all it is.

Thanks to you too, wireman. I have the parts on order, so hopefully when the work is done all will be well.

Scoot Jockey wrote:

Hello again,

Well I retarded my timing and my engine sill sounds like a diesel or a VW bug engine with a lot of valve noise. Clack, Clack, Clack!

So I checked my valve clearances (after checking the torque of the cam caps)and one valve was at .09 mm, two valves were at .15mm and the remaining five were at .12mm.

So it appears I must reduce the clearances on 7 of the valves to get into the .5 to .10 range.

My question is, would the excessive clearances noted above result in the noise I am experiencing? Have I found my culprit?

Again, my bike is a 1976 KZ 900, bored to 1075cc with a MTC kit and .385 cams (Z2 grind).

...<br><br>Post edited by: Scoot Jockey, at: 2006/07/02 18:10

With any aftermarket cams I'm aware of .006"-.008" is pretty much standard. Sounds like most your valve clearences are close, actually most are on the tight side for most any aftermarket cams I'm aware of. I would never set up a new build top end with anything less than .006"....mod

Post edited by: modprod, at: 2006/07/02 22:14

modprod wrote:

Scoot Jockey wrote:

Hello again,

Well I retarded my timing and my engine sill sounds like a diesel or a VW bug engine with a lot of valve noise. Clack, Clack, Clack!

So I checked my valve clearances (after checking the torque of the cam caps)and one valve was at .09 mm, two valves were at .15mm and the remaining five were at .12mm.

So it appears I must reduce the clearances on 7 of the valves to get into the .5 to .10 range.

My question is, would the excessive clearances noted above result in the noise I am experiencing? Have I found my culprit?

Again, my bike is a 1976 KZ 900, bored to 1075cc with a MTC kit and .385 cams (Z2 grind).

...<br><br>Post edited by: Scoot Jockey, at: 2006/07/02 18:10

With any aftermarket cams I'm aware of .006"-.008" is pretty much standard. Sounds like most your valve clearences are right on the money, actually some are on the tight side for most any aftermarket cams I'm aware of. I would never set up a new build top end with anything less than .006"....mod

hes got one at .09,2 at .15and the other 5 are at.12maybe its just me and my old school math skills but it seems like all 8 are outside the limits of .10 max and they will be noisy!:whistle:

Post edited by: wireman, at: 2006/07/02 23:33

His post says: .09 mm, .12mm and .15mm. My old school math says they are tight. It's anybodies guess what he actually has or if he's referring to metric or inch but his post says "mm". I had replied to an earlier post of his about this top-end noise issue. He put a 1000 block on a 900 bottom end and I ask him if he'd clearenced the cases for the 1000 block he didn't answer if he clearneced the cases or not just that he was sure the noise wasn't block related????????? There are afew 900 cases that will take a 1000 block without clearencing but that would be very odd......mod

I could not find any specs on the "Z2" cam, but APE calls for .004" (.10mm) for both the 410 and 435 cams

www.aperaceparts.com/tech.html

If the bike has stock cams, the spec is .05mm to .1mm clearance for a 903cc head. The clearance is a bit greater on the 1015cc head. The measurements listed don't seem correct as the blades on a feeler gauge go:

The clearances listed are outside (wider) than they should be but won't be excessively noisey... a bit of clatter but they sure won't hurt much. If you are running stock cams, I would only worry the .152mm clearance and only take it down on shim size from whatever is now used. A little wider than is called for won't hurt a bit and trying to reshim .127mm widths down will result in fairly tight cleanances... I suspect it wouldn't do a lick of harm to shim to the KZ1000 spec which is a bit broaded... .05mm to .15mm

one thing I havent heard any comments on is the compression ratio, wonder if its got a set of high comp pistons with some low octain gas

Hello again - let me address some of the comments:

Compression ratio - I'm not sure of the numbers, but when I bought the piston kit from Cope, they specified it was a 1075cc MTC street kit, so I assumed it meant a street ratio.

Block - It is a 1000 block, and when I first put it on the case, the crankshaft didn't seem to impact it. But there was no clearance work done. The noise I hear is clearly a top end noise, so I hope the block is not an issue.

Measurements - I was using a set of feeler guages that had both std and metric readings. The metric readings were as follows:

5 valves were at .127mm
2 valves were at .152mm
and the final valve was between .102mm and .076mm. The .102mm would not fit and the .076mm had a lot of room so I estimated it to be .09mm.

So if these clearances are not big enough to account for my noise, then I guess I am out of options. Since there are no shops in my town that have people experienced with modified KZ engines I cannot seek professional advice.

I think I will go ahead and get the shims to adjust the clearances between .05mm and .10mm just to see if the noise goes away. If it does not, then maybe it is time to pull the cylinder head and cylinder block and try something else. I suppose I could find a stock 900 block and a set of stock cams and go back to the basic set up. I really wish I would have done that to begin with. Using all these high-performance parts was a bad idea for someone with no experience like me.

Exactly when does it make noise? All the time, at idle and running? Low rpm when you open the throttle while riding? Does it do it when you hold the clutch in?

There are lots of things that could make noise, but they make noise under different conditions, so we need more info

My stock 900 makes a lovely ticking/tapping sound that is fairly noticeable at low rpm and lasts until it comes up to full temp. Not too sure what it is as my valves are all within spec. I gave up worrying about it a while back and have 4000+ miles since my rebuild.