1978 KZ650B Not Getting Fuel

Long story short, I have rebuilt the carbs three times and am planning to do it again unless someone here can help me out.
The bike started easily with ether, but not so much now that I've been futzing with the timing to make sure it's right, and I believe it is, now, but that's another story. I had a friend of mine who seriously works on bikes and he said it looks like I have it correct, but he's stumped too as to why I can't get it to fire with gasoline.

The carbs are thoroughly clean, jets clean, bowls clean, all the associated carb-bowl passageways clean and checked for positive fuel flow and/or air, the manifold boots are like new and tight, with no cracks or age showing - indeed, they look new - I have spark at all four plugs as well as new coils and wires - but I am not getting gas to the combustion chamber, and I don't know why. What am I missing?? A safety feature, maybe? Kickstand switch?

Fuel floats are set to 23mm +/- from the carb bowl mating surface (not the rim), and I do have positive fuel flow to all four carbs....I pull in the cluctch, no throttle, and hit th estart button and she will crank all day long, but No Fire.

Compression is #155 - #165 each cylinder...air screws are set about 1 1/2 turns out as per the manual...

I am mystified. I am going to go back over Everything again, but...Anybody...?

Just had an idea: The carb vacuum tube is hooked up, but what about the carb vent hoses? Do They need to be blocked, or 'whatever"? Doesn't make much sense if it's a vent tube, but does that have anything to do with it?

My Clymers manual only shows how to take out the jets - can the choke cylinders be cleaned, and how would you do that?

The vent tubes need to be open - not blocked. Have you tried starting the engine with the petcock in the "reserve" position? I know it shouldn't matter if the petcock is working properly, but it may be worth a try. Ed

The carbs are probably fine , my guess is that you have a problem with the hoses or petcock.
try starting it with the petcock selector in the horizontal (prime) position

The 78 model has a vacuum activated petcock and will not work with out a vacuum , but it will allow gas to flow in the prime position.

Here is the official Kawasaki shop manual for the 78 kz650 that you can down load www.kzrider.com/filebase/download/15-kz650/383-kz650b2-own-man

We tried that last night, in Prime, but no go. Haven't tried the Reserve position, but I would think Prime would put gas in there anyway...I'm getting plenty of gas to the carbs, it's just not igniting from there.

The manual doesn't mention the choke system, though - it seems to operate as it should, up and down and all the choke tubes move smoothly - but could the choke tubes somehow be clogged, or otherwise messed up? It IS an air passage, I've just never really cleaned this type before; I'm afraid I'll screw something up. Is there anything in there that doesn't like being disturbed?

Is there an app for that?

PS: bluej58, that link is for the KZ650B Owner manual, not the shop manual, but thanks anyway; I'm sure it will come in handy!

You only cleaned the carbs not rebuilt them,
Patton posted a diagram on cleaning all the carb circuits but I didn't find it .

Pic of the carbs? VM carbs have a jet in the bottom of the tubes going to the bottom of the bowles. Use a guitar string or strand from a wire brush to be sure they're clear along with the pilots. The holes are that small. Also if the H/T plug wires are reversed would cause a no fire condition.
Steve

PS: bluej58, that link is for the KZ650B Owner manual, not the shop manual, but thanks anyway; I'm sure it will come in handy![/quote]

Sorry, wrong one, unfortunately this is for the 77 which does (not) have a vacuum activated petcock, even so it is the best cross reference one available here for your bike.
www.kzrider.com/modules/ServiceManuals/K...Service%20Manual.pdf

This is from my sons 78 kz650, it has the prime in the down position, the clear pipe coming out the side is the vacuum line


The black pipe is a breather and the clear is the other end of the vacuum line , there are 2 breather pipes and 1 fuel line and 1 vacuum line

If you cleaned the bowls, I'm sure you cleaned the channel and jet used for the starter circuit:

Best to check the fuel level with fuel in the carbs like this:

yup, I had trouble with a starter jet before, simple fix, squirt some carb cleaner down the pipe channel and see if it comes out the bottom

Actually, I think I may have found the problem - (I hope). My carb slides appear to be way out of spec. Page 48 in my Clymers shows the gap between the end of the slide and the bore as 1.1mm, and they are all about a quarter of an inch off that. I'm just having a devil of a time setting that indicated gap. I get it to spec, go to tighten the adjusting screw locknut and set-bolt, and the set-bolt pushes up the slide! Maybe I'm doing it wrong...?

Also, where is the "throttle pulley adjusting screw"? Is it that little springed screw on the mounting plate side of the carb bank, right next to the pulley stop?

I got it; I was just being too gentle. Slide clearance though is abit fuzzy the manual states 0.79mm for the pilot type screws, and 1.1mm for the air screw type - I *think I have the pilot type in my carbs, but the little plastic extenders are missing...can anybody give me a little clarity on which setting to use?

Besides the cut-out on the opposite side of the slide, the diagram in the manual shows a setting of 0.79, so I think I'm going with that...