TOPIC:

Check endplay. Too much can fuck up the rotor, and cause an idle noise.

Thats great about the crank!! I wonder how many got factory installed with a tight spot unnoticed and are still running today.

Swest could it be the starter clutch?? I ask because I had chattering at Idle on a GS Suzuki and it was the starter clutch , the springs that pushed on the rollers where out of spec and it caused the rollers (the ones that grab the crank) to chatter at idle.
Dont really know how the gs and the kz compare in that area ...just thinking out loud.

I'm thinking about the select-fit damper washer behind the starter clutch. I understand it's there to prevent an idle rattle, and if endplay is excessive it will never be tight against the case (like it's not even there).My book doesn't give an endplay spec, but it should equal the crank thrust washer clearance. And you may be able to check it by just pulling the advance cover.

I guess I'll have to open it up again.
Steve

SWest wrote: I guess I'll have to open it up again.
Steve

Steve. Do me a favor and just remove the advance cover and see if you can pull or pry the crank side to side. If I'm looking at this right you shouldn't be able to with the rotor and damper washer in place. I think the washer takes up the endplay pulling the crank to the left. See what I mean?

I'll give it a shot. On the original Z1 motor, I went down on the right side and smashed the cover. The crank would go in and out a little at idle after that. I rode the bike like that until the wreck in 86. I'm going to check the carb sync. It would chatter too.
Steve

I'm wondering, is excessive endplay is the issue, that the thrust bearing may be loose in the case just like mine was. Did you check that during the last assembly?

Everything was tight. That broken pin and the amount the 750 crank was moving tells me it's not such a big issue. It sitting on the bench looks just as good as when I put it in. You all saw how I "rode the piss out of it." I'm glad I didn't know but obviously it didn't much matter. Goes to show how tough these motors really are.
Steve

This is #1 piston when I ran it out of oil in 13. STUPID. You can see most of the wear is on the right side facing the journal with the broken pin. I'm still running the others. They were undamaged. I didn't realize how bad the valve guide seals really were. I was planning to order a new sight glass and the idiot light was undependable. I knew better and wound up cleaning the old one with carb spray and Q tips. It's still in use. I try to stay on top of things now.
Steve

Man, you got your money's worth out of that one.

I few years back I was riding off-road in the Rockies with some buddies of mine. One of them with a Honda XR600R made sure he changed the oil before the trip. Sure enough he didn't tighten the drain plug. We we're pretty deep in the mountains when the plug came out, and he didn't realize until it powered down and seized. It was a tough trek towing him back with a rope. After we got back to the cabin and the engine cooled down, replaced the plug and filled it with oil, it kicked over and ran fine. No noise or smoke. XR engines are as close to bulletproof as you're gonna get. But of course he sold it as soon as he got home.

I rode it like that until the 1015 barres came. Had to use the stock pistons and rings that came with them. A year later I had a new piston and did a valve job. These bikes are tough.
Steve

Guess I jumped the gun. Been spinning the crank and still feel a slight tight spot. It's random, not any particular number of turns. I put a dial inch pound torque wrench on it and the tight spot is only 5 or 6 inch pounds.

I'm getting a straight edge to check the line bore.

It's either the bore is off, a bad bearing I can't detect otherwise, or maybe just the .0025" run out at the center of the crank. The runout is within specs but new is closer to 0. I'm sure most people wouldn't have noticed it. Maybe I'm overanalyzing.

I spoke with Stan at grc cranks and he suggested swapping case and/or crank and see which fixes it. Wish I Had a few laying around.