TOPIC:

New member here. I have an 1980 1000 LTD with about 14500 miles. Most of the miles were early in its life with the bike sitting most of the last 10 years. Anyway so far I have replaced the battery, cleaned the carbs and lubed up the mechanical advance.

The bike starts easy and idles fine (an occasional pop noise), all exhaust pipes heat up quickly. The problem is when under load if I hit the throttle pretty hard it stalls a little and will never climb above 6500RPM, this usually results in a large backfire through the exhaust when letting off.

Also did a commpression test(WOT) with these numbers.
150, 120, 115, 120. Added oil and all numbers came up from 15 to 25. I understand the rings are a little weak, but would this cause the above problems under load.

Any ideas, Thanks.

Checked/adjusted the valve clearance yet??

Not yet because I thought with the wet compression coming up I thought that meant the valves were good.

Thanks.

CG50:

Steele is correct...valve clearances first...then you might worry about the valve stem seals, particularly if the bike has been sitting for a while:) Then worry about the carbs

The easy-fix place to start looking is with the rubber carb holders that join the carbs to the head. From the sound of things, one or more may be sucking air at the higher rpm...

Check for cracks or holes, but I'd suspect the seal between the holder and the head casting - it's a sheer butt-joint arangement that just begs for a fine film of silicone to be applied to ensure a good seal.

Hope that helps...

And they are cheap to replace too !! About $60.00
for a set of four from Z1 Enterprises.
www.z1enterprises.com/detail.aspx?ID=97
Pat

Dang it..

Post edited by: patmann, at: 2006/06/07 12:39

Thanks for the responses guys. Just checked the valve clearances, a couple were at .05mm, all others were less.

I am a little confused still, if there is some clearance would'nt the valves be closing, or are we saying there is a least .05mm expansion of the valve when they are hot.

Post edited by: computerguy50, at: 2006/06/07 15:15

I'm confused too...so your clearances are less than .005?...like .0025?

McDroid... The MIN clearance for the early KZ900 or KZ1000 is .051mm. The max is .102mm (MEMORY). This fella very likely can't measure a smaller clearance nor does he likely have any shims. My FIRST suggestion would be that he measure all clearances, then purchase a Kaw shim tool and last to remove and write down all shim sizes on his bike. He will likely need a digital caliper for that since most shims have worn numbers.

Next, I suggest he have a look at the article on this subject on my web site as I have explained it soooo many times, that it motivated me to write stuff down and put it on my site. Go to www.wgcarbs.com and look at the "valve clearances" link... FWIW... metric feeler gauges go: .051mm, .064mm, .078mm, .102mm, .127mm At least the ones I am familiar with anyway... I also put the formula for figuring out which shim is needed I believe... also, there is a small bit of explanation for why clearances grow less with engine wear and not more.

WG...that is what I was sort of getting at:)

Sorry got confused with the U.S. vs Metric. I remeasured.
First cylinder E-.05mm I-.08mm.
Second cylinder E-.10mm, I-.08mm.
Third cylinder E-.<.04mm bucket does spin, I-.05mm.
Fourth cylinder E-.10mm, I-<.04mm bucket does spin.

My lowest gage goes to .04mm.

How much can a valve stem expand when heated up?

Do you guys feel an adjustment is nessesary on the 2 close ones where the bucket still spins.

I do have your guide wiredgeorge, got me this far.

Thanks.

Post edited by: computerguy50, at: 2006/06/07 16:10

Post edited by: computerguy50, at: 2006/06/07 16:11