Can't restart bike...what am I missing?

How much fuel was in there? Try running it on reserve and see if your problem goes away. If you're getting slow fuel flow when petcock is on that could be your problem.

didnt realize your carbs were such a pain in the arse to check levels.
bet you're glad you havn't got 4 of the fuckers.

The carbs at hand apparently have simple, single-function drain screws (remove screw to drain the float bowl), and with the float bowl nipples serving only for overflow discharge.

For a freely downloadable workshop manual, may click on this link
www.kz400.com/
Next, in the left column, scroll down to and click on Workshop Manual

Or, use this link to go directly to the Workshop Manual
www.kz400.com/WorkshopManFrameset-5.html

See page 106 for information about the clear tube test for determining the service fuel level, which includes the following illustration:




As to the fuel tap, it's probably a manual petcock with STOP - ON - RES positions,





But the fuel tap (aka petcock) might possibly be either:
• a manual petcock with ON - OFF - RES positions,
• a vacuum-operated petcock with ON, RES and PRI positions.

With a manual petcock, STOP and OFF mean the same thing, that is to say, "No fuel flow from the tank."

For the clear tube test:
• manual petcock ON or RES fills the float bowl;
• vacuum operated petcock PRI fills the float bowl.

Good Fortune!

The special tool isn't essential.

A clear plastic tube with suitable outer diameter will self-thread into the open hole from where the drain screw has been removed.




In my experience, using an appropriately size clear tube is faster than fooling around with screwing and unscrewing the special tool.
Could consider carrying a float bowl to the hardware store or hobby shop or aquarium supply to help assure getting the correct size tube.

Of course, a fuel-proof plastic fitting that inserts into the drain hole to provide a leak-free connection onto a clear tube may also suffice. But, honoring the KISS principle, I just use the clear tube alone.

Good Fortune!

I would add one thing to Patton's last post. If you have the manual tap and the fuel level is very low in the tank, no fuel will flow. When the level in the tank gets low, the fuel tap must be switched to RES in order for fuel to flow. This is a subtle hint to the rider that it is time to find a fuel station.
Try switching to RES and see if the fuel flow.improves.

TexasKZ wrote: I would add one thing to Patton's last post. If you have the manual tap and the fuel level is very low in the tank, no fuel will flow. When the level in the tank gets low, the fuel tap must be switched to RES in order for fuel to flow. This is a subtle hint to the rider that it is time to find a fuel station.
Try switching to RES and see if the fuel flow.improves.

Thanks, TexasKZ!
So true.

I edited the post to include either ON or RES to allow fuel flow from the tank with a manual petcock when determining the service fuel level by performing the clear tube test.

Good Fortune!

If your in the float bowl then check the pilot jets. They're next to the main jet circuit. Use a small flat screw driver and pull them out. The hole is so small it is hard to see through it even when not clogged. I use spray choke cleaner and a guitar D string to clean it out. Don't use anything too big or you will ruin the jets. Don't get the carb cleaner on the rubber parts. Make sure the slides move up and down freely. If they are the CV type, there will be a vent at the top back of the carb. Push the slide up with your finger and hold your thumb over the vent. The slide should stay put of fall slowly. If it drops quickly, you need new diaphragms.

The strainers in the tank or pet cock bowl may have some garbage in them, rust etc. too.

i'd set the pilot screws at 2.5 turns open for a start. After the bike warms up a little tweak them until the highest idle speed is achieved. An increase in rpm when you turn off choke suggests air leaks and/or lean running. Is the bike stock? Airbox installed and stock exhaust? The bike won't run for crap without the airbox and filter for example. Any changes from stock will require rejetting. And speaking of jets, aftermarket carb kits are a big gamble. Often times the sizes don't match the originals, and/or they are of inferior quality.

The airbox is stock. NOS carb holders, stock size jetting, new rubber PVC connector for carb to airbox connection.

One thing I'm not sure of is when I had purchased a single-carb manifold from 11th hour industries, it came with gaskets. Once I switched back over to the stock setup, I retained the gaskets. Of course, I now am noticing there were no gaskets according to the parts diagram. Is it possible I'm getting and air leak there? I've sprayed it to check for leaks before and didn't notice anything.

So today I fired it up after confirming I had put a gallon of gas into the tank. She started up on the first kick, choke on. Started to cut back on the choke and idle rose. I had hooked up a timing light verified I was getting spark to both plugs. Bike died, managed to get it restarted. Both exhaust are equally warm, to the touch (no infrared thermometer.) Idle screw out to 2.5 turns from 1.5. After about 4-5 go-arounds of this I started to get a little trouble starting it again. Verified I was still getting spark (via timing light), yet no start. Choke off at this point. Decided to give it some throttle immediately after kicking it over. Sure enough, it would fire up with throttle engaged after kick. Had to keep throttle pulled back to maintain a low and rough idle. Slowly released throttle and achieved a better idle but throttle was still engaged. By the time I released the throttle the bike died.

I still need to reverify the valve clearance but I'm pretty sure they're within spec.

Carb Diphragms.

You say you have new diaghrams, change them, if it idled with choke on, and the rpms raised with it off, then the bike died, you have a pilot (idle fuel) supply problem or fuel flow from tank problem, either clean the carbs and change the diaghrams or put in gas and check flow. Most likely; clean the carbs and put them together right, mickey mousing them wont do you any good man