Got spark but won't start

Was wondering if anyone could help out a newbie. I'm working on a 78 KZ650 bobber project and got her all together and mostly wired up. I have spark (seems pretty weak to me though) and she'll turn over with the start button, but I can't so much as get a chug or any indication that it will start. Here are some things to note that may or may not make a difference.
1. The only thing not wired up are the lights and gauges. Not planning on putting the gauges back on. Just a headlight, taillight and flashers when finished.
2. I don't have an ignition switch, so I have temporarily wired the brown and white wires together as if it were in the "on" position.
3. The coils are not bolted on but are hanging loosely on top of the engine until I can weld in new mounts. (It's a 650 motor on a 1000 frame so the coil mounts didn't match up to my coils).
4. Gas tank isn't mounted yet, so I filled the carbs up with gas until the overflows were overflowing to make sure there was enough gas in the carbs to get her started.
5. Have pod filters and haven't changed any of the jets or anything yet. Thought it would at least start even if it runs badly.
I think that covers it. Any ideas? I'm wondering if it might need new points or coils. Maybe something to do with the clutch not being pulled in enough or neutral switch may not be completing the loop because it might be in the gauge or light wiring?

Thanks,
Bryan

Sounds like you should be able to get her to fire at least.
The coils on my bike are from a different model kz.
I have them bolted with one bolt at the front, and zip tied at the back as the holes don't line up.
Try switching the green and black coil wires, as you may have something reversed in the ignition system, and reversing the green and black wires will confirm if this is the case.
If you don't have the proper jetting, the air/fuel mix would be way off, but you'd think she would still burp or something.
I'm suspecting something electrical, but not light related.

If you open the left points manually does the 1/4 coil fire. A weak coil on a 650 is a bear to start with the electric starter, have you tried to kick it over to see what happens? You may try spraying some carb cleaner in the carbs to see if will at least burp

btkz650 wrote:

1. The only thing not wired up are the lights and gauges. Not planning on putting the gauges back on. Just a headlight, taillight and flashers when finished.
2. I don't have an ignition switch, so I have temporarily wired the brown and white wires together as if it were in the "on" position.
3. The coils are not bolted on but are hanging loosely on top of the engine until I can weld in new mounts. (It's a 650 motor on a 1000 frame so the coil mounts didn't match up to my coils).
4. Gas tank isn't mounted yet, so I filled the carbs up with gas until the overflows were overflowing to make sure there was enough gas in the carbs to get her started.
5. Have pod filters and haven't changed any of the jets or anything yet. Thought it would at least start even if it runs badly.

1. Doesnt matter.
2. Doesnt matter.
3. Doesnt matter. Make sure that the voltage at the coils is the close/same as voltage of the battery.
4. BE CAREFUL. In order to start properly, the choke circuit should be on with no throttle input. When this is engaged, it sucks uo ALOT of gas quickly and the engine will lean out in just a few seconds without a steady stream of fuel!
5. Not so. Without proper jetting most bikes are VERY difficult to start without full choke and the mixture screws cranked out many turns.

Get it all together correctly, then start troubleshooting.
Jets especially!

GL!

Thanks everyone. I tried starter fluid and nothing. Checked the points and they are getting spark but seems to be better spark on the right than on the left. Since I don't have a fuel tank on it yet, I just filled the carbs until they overflowed so I may have flooded it. I did go back a day later and tried again with no results. I tried with choke full on and no throttle. Still nothing. Could it have anything to do with not having any exhaust hooked up yet?

"I don't have an ignition switch, so I have temporarily wired the brown and white wires together as if it were in the "on" position."...

Maybe a miss print, I have the wrong schematic or I'm missing something here but....

Brown to white wires:
White is incoming +12Vdc (battery voltage) into the ignition switch.

Brown wire ignition switch output feeds instrument cluster lamps and rear brake light switch only... In my schematic anyways....

In this case, you don't have coil voltage!

Get your self a 20amp on/off switch from auto parts store. Ohm out the switch insuring it's in off position (no continuity between legs).

Connect ignition switch white conductors to one switch leg, connect yellow engine stop switch conductor or red/yellow if bypassing engine stop to the other switch leg for coil and ignition plate switched voltages....

Insure engine/frame is indeed battery ground potential!

While at the AP store, get your self ~ 4 feet off 1/4" fuel line... STOP poring directly into the carbs, use your gas tank as your source of fuel.

Bet you a Dr Pepper she'll start now...

OMR

Just in case... wiring diagram...

But if I were wrong, why does it turn over when they are crossed but it won't when I disconnect them? I hope you're right though, because that would be an easy fix.

I think my ignition switch is a 4 wire unless I'm guessing wrong (very likely). Here's a pic of the connectors. I determined the 4 wire to be the ignition and the 9 wire was probably to the gauges. Can anyone verify based on these photos?

Here's the other one...

I have spark at the plugs, so I'm guessing I have spark at the coils.

Old Man Rock wrote:

"I don't have an ignition switch, so I have temporarily wired the brown and white wires together as if it were in the "on" position."...

Maybe a miss print, I have the wrong schematic or I'm missing something here but....

Brown to white wires:
White is incoming +12Vdc (battery voltage) into the ignition switch.

Brown wire ignition switch output feeds instrument cluster lamps and rear brake light switch only... In my schematic anyways....

In this case, you don't have coil voltage!

Get your self a 20amp on/off switch from auto parts store. Ohm out the switch insuring it's in off position (no continuity between legs).

Connect ignition switch white conductors to one switch leg, connect yellow engine stop switch conductor or red/yellow if bypassing engine stop to the other switch leg for coil and ignition plate switched voltages....

Insure engine/frame is indeed battery ground potential!

While at the AP store, get your self ~ 4 feet off 1/4" fuel line... STOP poring directly into the carbs, use your gas tank as your source of fuel.

Bet you a Dr Pepper she'll start now...

OMR

Just in case... wiring diagram...

As mentioned, possibly schematic is wrong but....
What is your KZ's exact model B, C, F etc....

"I have spark at the plugs, so I'm guessing I have spark at the coils."...
What is the voltage reading to the coils?
Battery +12Vdc or higher....

Are you positive the kill switch isn't partially shorted?

"why does it turn over when they are crossed but it won't when I disconnect them"...

When what are crossed or disconnected?
Which conductors are you speaking of....

Starter turning the crank over doesn't constitute proper voltage to coils & ignition components if that's what you meant.

Are your plugs all gas fouled?

One thing I missed, what about your cam/valve clearances, tooth count, rotations etc....

Good compression?

Make sure the engine to battery ground is excellent. (Via nice thick wire).

If your getting spark (and it is properly timed), then all you need is compression and a close enough ratio of fuel and air.

1. Make sure timing and firing order. 10 degrees before top dead center, on the F mark of advancer for idle.

2. Do a compression check. All the cylinders need at least 90+ pounds of compression to run fairly smooth, and they should be within 10% difference of eachother.

3. Turn your mixture screws out 2 turns and turn the idle screw in to increase idle 3 times.

Full choke, and no throttle. Crank bike for about 4 actual seconds. Count them, 1 mississippi...

Sometimes the advancer is installed backwards/coil signal wires crossed. Usually you will get a seriously loud afterfire warning you of this.

GL!