WON'T START AFTER OVERHAUL

Hello fellow riders,
Just finished a complete tear down and rebuild, engine and carbs. Everything hooked up, lights working etc. Primed the carbs, checked for fuel in each one, and tried to start. No fire at all. Pulled plugs, dry but have a weak spark but a spark none the less and no gas smell on them. Any help would be appreciated. Very frustrating and discouraging lol. I even put ear plugs in (exhaust not on yet) cause I was so confident it was going to fire up and BLAT at me lol. Thanks in advance, jon
Almost forgot, 1981 KZ1000 J, all original equipment.

Put the exhaust back on and try again. And make sure to properly prime the carbs.

Exhaust not on? :blink: It's probably a very good thing that the engine did NOT start. You should finish putting things together before starting the engine or you may end up damaging the exhaust valves. Ed

Thanks for your replies. The reason I didn't put the exhaust on was because I wanted to see and hear how each cylider was firing. I thought since some people run straight pipes that it wouldn't hurt to try and start it and not run it too long, just my opinion and I do appreciate yours. I did notice an intake valve sticking open and caught it before anything was damaged, I think. The valve bucket was hung in the chamber sooooo I tried pressurizing the cylinder and it was still stuck. I had to cut a slot in the top and pry it out. Now I am looking for a new or used valve bucket. Anyone got one lol. It's diameter is 1.298", 1981 KZ1000 J. Thanks everyone. jon

Cold air hitting a hot exhaust valve, WARP. :ohmy:
Steve

I knew there was a reason lol Thank you so much. Jon

If the valve was stuck open more than just a tiny bit while the pistons were going up and down, there is a good chance that the valve and piston made rather violent contact.

A really weak spark may not have enough energy to ignight the charge under pressure.

In a case like this where everything has been apart, nothing can be assumed. IMO, it is best to insure that all the basics are confirmed first.
Are the secondary wires from the coils connected to the correct sparkplugs?
Are the coils correctly connected to the ignition system?
Are the coils getting full battery voltage - 12.5 - 13.5v?
Is the battery good? Only a load test can tell you for sure.
Do the battery and ignition systems have clean, tight grounds?
Do the carbs have the correct fuel level as confirmed by the clear tube method? If it is too far off, starting may prove difficult.
Were the carbs proprely synchronized on the bench before installation? This will get them close, but they will need fine tuning when the engine is running.
Are the cams properly installed? With the crankshaft at TDC, do the camshaft timing marks line up as the are supposed to?
As mentioned above, the exhaust and intake systems need to be in place.
I have probably left out a thing or two, which is why a factory service manual is so important to have for the first ten or twelve rebuilds you do.

Thanks for your reply and will double check ALL of the above. Tell me a bit more about the"clear tube method" please. It did pop off and almost run before I discovered my valve hang up. I didn't catch it when rolling over by hand so now the valve cover is off and waiting on a new valve bucket as I had to cut the stuck one out. Valve no longer hung up lol. have to pull the springs while head is on to check the valve bucket bore. Shouldn't be an issue. Thanks again and looking forward to your reply. I do have a good manual from Kawasaki so I shall read a bit more. Cam timing was good but have to redo now that the intake cam has been removed. Thanks, Jon

Here's an image that show the clear tube test. You should check a manual to see the correct fuel height for your specific carbs; it may be different than the one shown in the image. Ed

Not sure what you mean by valve hung up. Was the valve stuck or the bucket. I hope you used proper assembly lube on your valve train. Either way I would be concerned if the bucket or its slot is buggered up badly as oil will leak down scored surfaces and get to the valve tem oil seal way easier than intended. Likely an oil seal failure in the making. If it burns blue smoke you'll know the culprit. Also, as others said, check the timing and valve train to be sure the valves and pistons didnt' hit and that the valves are operating correctly - piston clearance and shimmed properly. I have had several of these KZ motors completely torn apart for main seals, bottom end, top end, and split. If you follow the Kawasaki manual you should be fine. R

I started another thread under WANTED INTAKE VALVE. After reading your reply here is an update. First a bit of my mechanical background lol. This isn't my first rebuild. I have been building engines for 40 years, was a Navy engine room guy and a mechanic in a Nuclear Power Plant for 21 years. Not my first engine rodeo just the first motorcycle.
This was a complete rebuild cases split, new gaskets and seals, valves lapped and clearances checked. Timing set per the manual. this rolled over fine by hand. The issue when I tried to start was that somewhere #1 valve bucket bound up, probably from me missing some sand after blasting even though I cleaned all pieces many times with air, water and brake cleaner, wire brushes etc. I pulled the valve train and ended up cutting a slot in the valve bucket and getting it out. Bad burr in the bore which I honed out. I figured I would pull all the buckets out, clean bores and buckets so nothing would flush back into the oil system. Found #4 intake bucket bound up, cut a slot and removed, burr in the bore, honed all is fine now BUT after pulling #4 intake valve and checking, I found it bent. No damage to piston. All other buckets came out fine, flushed oiled and replaced. Waiting for 2 buckets from a fellow KZRider member. I'm in need of 1 intake valve and one valve seal. That's where I'm at, waiting for parts lol.I appreciate your reply and assistance. Thanks and any ideas will help. Be well, Jon