Won't START!!!!

Hey Fellas,

I have a 1995 KZ1000P that will run only on cylinders 3 and 4 and then only with full choke. I have played with this dude for a long time and am STUMPED! Please give me your thoughts.

1) Bike has a completely rebuilt head with new valves, valve guides, and new piston rings. Compression is now 180psi in all 4 cylinders cold.
2) Carb was completely dismantled, cleaned/dipped, all passages blown out and all jets cleared, new O-rings, etc. All 4 rubber diaphragms look good and all 4 needle/floats seal.
3) All 4 spark plugs have a nice blue spark and one coil is connected to 1-4 while the other to 2-3.

I removed the emissions air valve that is operated by the carb vacuum and plugged three carb nipples while one operates the fuel petcock. Also, I rebuilt the fuel petcock and it works flawlessly. I have it on PRIme when trying to start/run and all 4 carb bowls are equal in gasoline volume when I empty them.

Now, I did notice that the spark plugs on cyl #1 and #2 were DRY after inspecting. Also, with the air filter boots removed, I used my hand to block #1 and then #2 and both times the idle speed increased. So, I then set those two pilot screws to 1 turn out instead of 2.5 and noticed a slight improvement. It seemed like cyl #1 started to fire a bit.

Then figuring that I was running way too lean, I put the air box boots on, attached to the air box with air filter and seat, and tried again. Same problem, cyl #1 and #2 won't run. Lastly, all 4 front carb rubber mounts looked good with no cracks (maybe I missed a crack?). That is about all I can imagine at this point, is that the front rubber carb mounts for 1 and 2 might have HUGE, non-visible cracks???

PLEASE HELP, as I am going nuts with this one!

Timing ??? Check ignition and cam timing , Assume the cams are off time and check to eliminate as a potential issue / and valve lash
Plug wires on right cylinders ??
Carbs maybe clean , but could still be plugged in passages ?????
As mentioned air leaks.
Eliminate some more variables and get back to us
Good Hunting
Dave

Did the valves get adjusted and the float levels in all the carbs all set to within parameters too?

For the hell of it, switch 1/4 and 2/3 coils leads coming from the points cover and get back to us.
Steve

Thanks for writing. The valve clearance is all within spec and the carb float levels are perfect (took some tweaking the float tangs). BTW, if I have 180 psi compression all around, doesn't that eliminate the valves as a problem? Just asking, as maybe there's something I'm missing in that conclusion. Thanks again for your time!

If it only runs on choke then the pilot circuits are still clogged in the carbs.

Try a leak down test. Also make SURE the timing is spot on. But TBH it sounds more like a gas issue. However, check all four plugs are firing, especially 1 & 2 when they're supposed to. Check the V on the coils, HT leads etc etc

KZ1000P1995 wrote: Thanks for writing. The valve clearance is all within spec and the carb float levels are perfect (took some tweaking the float tangs). BTW, if I have 180 psi compression all around, doesn't that eliminate the valves as a problem? Just asking, as maybe there's something I'm missing in that conclusion. Thanks again for your time!

The compression test shows you that the rings on pistons have a good seal against the cylinder walls and that the valves have a good seal against the head(when closed), but it won't diagnose how far the valves are when they are open and letting in gas (or letting out exhaust).

And just to double check, you used the clear tube method to check the float levels?

Also, out of curiosity, when you removed the emissions system did you cap the ports(or run a hose from one to another) on the cam cover plates? And did you plug the hole in the top, front of the airbox, that the emission hose went to?
-Greg

Thanks again fellas!

I've been thinking about this day and night and believe the problem to be in the carbs/boots. Ignition is electronic with no adjustment and if the cam timing is off then cylinders #3 and #4 wouldn't fire either (?). Also, since 3 and 4 are both firing, bad coils can't be the issue. Now, even though I have a strong blue spark at #1 and #2, maybe they both still have issues? Maybe the HT leads/spark plug caps on #1 and #2 have issues that don't show?

I'm still thinking it MUST be the carbs and/or intake mounts, as when I had it running on only cylinders 3 & 4 with the air box boots off, I cupped my hand over carb #2 and the idle increased substantially. Same with carb #1. Maybe I'll try sealing the intake mounts with high-temp liquid gasket, check the carbs for the hundreth time and go again? I DID use the clear tube method regarding carb float bowl volume. Also, I removed the emissions, ran a hose from one 1/2 inch nipple on the front of the cam cover to the other, plugged the hole in the air box, and made sure the vacuum nipples on carbs #1 and #4 were plugged.

Regarding valve lash, this head was kind of a disaster after I took it to a local machine shop. The valves all had severe cupping with compression in the 30's when I bought the bike (didn't know). So I removed the head, inspected, and ordered new valves, valve guides, seals, etc. I didn't have the necessary tools to cut the old seats and took it to a local machine shop to have them "lightly touched" as they had almost no wear. Well, those butchers ground the seats down so deep that I then had to have most of the valves stems "tipped" and had to order several new shims to make everything fit. After I put the head back on the bike I measured the valve clearances and everything seemed within spec. That and the fact that I have 180 psi on all four cylinders makes me think it is more of a carb/intake issue.

Still, if I had a clue I would have already fixed this sucka, eh? I'll update later today and thanks again for all your help!

I've used :ohmy: Permatex on the carb holders. It worked long enough until I got new ones. If the leads to the coils are reversed, the bike will have spark and sound like it wants to fire. I've done this more times than I care to mention.
Steve

Okay, I tightened the carb mounts extra tight and it helped. Now only #2 isn't firing. Also, I noticed that it will idle at 1,500 until I pull the choke to full and then it takes off to 4,000 rpm. Oh, and I also checked for spark again at #2 and it's strong with blue/purple spark. Lastly, I noticed some backfire through the carbs, don't know which one, probably #2.

Sure seems to be pointing back to bad carbs and not ignition. Maybe a problem with valves too? Still, I would be very surprised if valves had anything to do with this. Any thoughts? Thanks for your help.

Make sure the pilots are clear using a guitar string or strand from a wire brush.
Steve