Return to the '77kz1000 problems

[81xsproject]

I wrote and posted this for the friend who's kz I am working on. I really am at a total loss.

Bike history: I got this bike from my X-father-in-law (XFIL) When I was in high school. It came to me in boxes and my uncle and I rebuilt it for my senior project. It came in boxes because while riding it, my idiot XFIL, who probably never reset the cam chain tensioner, just barely escaped wrecking it when (speculation and second hand info) the cam chain jumped teeth, the rear tire locked up, and the cam chain blew up. It was a long time ago, so my memory of the rebuild/reassembly is limited. What I do know is that we added a Wiesco 1045 kit, rebuilt the head, replaced some wear parts like the clutch friction plates, and added a Dyna III ignition. It ran decent and strong for the week between the end of high school and my departure to the Army. It was then moth balled and unfortunately tamper with by my unskilled XFIL while I was away because it wasn't running right. Now many years later with less that a hundred miles on the rebuild, I have spent the last 3 years trying to figure out what the hell is wrong with it. Since then, I found the cams each a tooth off (XFIL) and returned them to their proper positions. I have added Dyna coils and done the coil re powering mod. I have WG's bs34 conversion (which made a big difference). A compression test showed every cylinder was between 170 and 180. However, there was still the nasty grinding sound coming from under the clutch housing/oil pan area and though it runs and sounds pretty good, when riding there is definitely still something very wrong performance wise. Well a friend and I finally said the hell with it and did a complete tear down to find answers to our questions and to look for something wrong. Unfortunately, he have found nothing that looks even remotely wrong. None of the bearings feel sloppy, no gear teeth look bad, no wear marks in the jugs... I am at a total loss. SOMETHING is wrong but with nothing obvious slapping me in the face I am just very frustrated and fear that upon reassembly, the problem is waiting and I have to waist a whole gasket set for nothing. If anyone has any ideas, I am begging. I can measure or take pictures of anything. I just really want the bike to run or I am afraid it will just have to be parted out.

[randy]

anything blocking the exhaust?

tank cap vent clogged?

170-180 psi compression sounds high, although i'm not familiar with the KZ engine or specs. What is the compression supposed to be?

Too high compression maybe valves out of adjustment.

[Crazcnuk]

The ,normal' compression range for a 1985 VT1100 is 165-210psi, so I wouldn't assume this one is high, right off.

As with anything mechanical, a manual is a MUST!

[TopCatGr58]

Noise from Clutch cover/tranny housing?

Don't know but think it might be similar to the XS, in that the clutch basket has a gear that drives the oil pump, have heard of folks not getting it aligned right, bending or breaking the gear wheel?

With only a hundred miles on it, wasn't even broken in, so comp values will probably rise when rings are seated. Therefore, also the power won't be all there either until it breaks in, and could be damaging to try to put too much throttle to it too soon!

Also, with those comp values, are you using REG gas, or a higher octane??
T.C.

[81xsproject]

I believe 160 is normal and this has the wiesco high comp pistons. I have ran high and regular octane gas in it and didn't notice a difference. All the gear teeth look good. I always thought the noise sounded like it might be a primary chain, but the kz supplies its power from the crank by way of a gear that turns the clutch housing. So, no primary chain at all in these. I have run with the tank lid open before, no difference.

[dewibp]

Maybe the KZrider.com forum could help you......

[81xsproject]

Well, it is possible that I have figured out both problems. The KZ clutch basket has springs that sit in between the primary gear, that recieves power from the crank, and the basket itself. The two are riveted together:


The springs are supposed to be tight, but mine were sloppin around in there. I'm guessing this is the noise problem.

I had the head apart last night to lap the valves in and discovered that all four exhaust valves are slightly bent. Not enough that they would close, but they couldn't have been getting a good seal. Now, what I want to know is how do you get 4 bent valves with no visible signs on the pistons? And, furthermore, how do you get 170-180 psi compression readings with bent valves? I sure hope this is the problem.

[prometheus578]

Compression gauges can be notoriously inaccurate. I take the pressure number as a give or take, more interested in the relationship of compression between the cylinders.
I've seen plenty of bent valves... but don't recall ever seeing where they had hit on the piston. Happens so fast that it just doesn't leave a gouge or a mark. Valves are rather fragile... been easily.
Those springs, as you know, are torque dampeners of a sort. So the parts of the basket don't slam back and forth with each other... a gradual application of power. If they're loose, yes, that can cause noise as the components rock back and forth.

[AlanB]

Hi 81XS,

Usually, no matter how bad a clutch basket gets, they are a LOT quieter when the carbs are properly synched..........

AlanB

[81xsproject]

New update:
Well, there are no marks on the piston because the valves didn't hit the piston. Thanks to the idiot XFIL who put the cams in with the exhaust a tooth retarded and the intake a tooth advanced, the intake valves opened before the exhausts were closed and and bent them. All four intakes have little marks on the edge of the faces where they came in contact with the exhaust valves. The intakes appeared to be fine, but we decided, the hell with it, and are buying all new stainless valves.

[Crazcnuk]

I woudn't touch them, if you're getting good compression.

To get compression, they have to seal. That's all valves do. If they are 'slightly' bent, they will straighten out after a few thousand hammers with the valve springs.

The only reason anyone 'fixes' bent valve, or even knows they have bent valves, is because they can't get any compression, and so the motor won't run.

Also, with some of today's more exotic engines, it wouldn't surprise me if there are a few out there with offset (read:'bent') valve orientations right from the factory.

[81xsproject]

Well, when the E valves are in the chuck of my screw gun and spinning they look the tilt-a-whirl ride at the fair. Besides, on a bike with a KNOWN performance problem that up till now has been a mystery, I think it would be very stupid to put them back in, especially when considering that while beginning to lap one in only about 1/5 of the edge was rubbing against the seat. With the head upside down and MMO filling the head space all 4 drained out the exhaust ports. I would be willing to bet that valves have been 'hammered' about a million times since they were bent. Since it was impact with the I valves that bent them, we have ordered 8 new stainless valves from z1e.

[Crazcnuk]

But if that was the case, then there was NO way he would be getting good compression.

That's all the valves do. If they are only touching 1/5 of the way around, you will have next to 0 compression.

I suspect they got bent during the 'troubleshooting' phase, and not previously. Somewhere AFTER the compression test, and before the teardown. Maybe the cam chain was just that close to slipping and finally did.

Having bent my valves, during a tune-up, I know exactly how nasty that can be....

[81xsproject]

I think it is more likely that it happened while the cams were both a tooth off (before compression check and cam re-alignment) than the troubleshooting (where cams were re-checked to be sure they were correct). The chain is new and and the tensioner was set when the cams were re-aligned. If I get it back together and it still runs poorly, then it wasn't the bent valves. But, on the bright side, at least I won't have bent valves.

[Geezer]

If you haven't already, I'd clean the carbs again. If your XFIL was screwing with it, while you were gone, he probably left gas in the carbs too.

I think you're spot on going with the new stainless valves. Sometimes you can get reasonable looking compression figures with bent valves but not what the engine could make with good ones. Also a little oil in the cylinders can help mask the problem then add in that they were all bent the same and it will look from the outside that everything is fine.

Back in the day I remember solidly riveted clutch baskets being a high performance mod for these bikes as was the radial needle roller clutch release. I don't know how well these modes worked.

I had a 76 KZ900 for a short while with the same big bore kit. It went like stink and I think yours will too when you put it back together.

Geezer