Weak, tiny spark, kz750 twin

Ok guys:

New condenser (but not points, just cleaned them good)

New EMGO coil

Static timing set as per FSM (ohm tool on points, f on timing mark, move till read first bit of resistance)

New plugs (the old ones sparked at the base of center electrode, very strange..)

Getting gas.

Getting spark.

125 psi cranking, both jugs.

Rebuilt the starter clutch, now it (sorta) works better.

Valves set as per FSM

Judging by all the above, I SHOULD be running up and down the highway like a madman with the wind blowing through what hair I failed to pull out in my earlier frustration, celebrating a job well done.

INSTEAD: Here I sit in front of this computer wondering why for all that is good and Holy on Gods green earth will this damn motor STILL not start.

All I have been able to get is a backfire or two, then nothing. I tweak the timing and try again, and nothing.

I do have an absolutely worthless battery, and have been trying to start it by jumping from my truck battery. Perhaps THAT is my problem? Bad battery sucking up the juice before it gets put to good use?...

I am lost. I am going to get a new battery, and if that dont make a difference, then I am switching from points to electronic ignition....

Any more thoughts guys? I am still stumped..

If everything is set up and your getting spark (at the right time) and fuel. You may want to make sure the carbs are synched as close as you can get them on the bench, and make sure the jets are adequate for whatever filter/exhaust you are running.

I would just make sure that you are not fouling the plugs or letting them get too wet, as that may be adding to the trouble starting.

ElSombreroNegro wrote: ...Static timing set as per FSM (ohm tool on points, f on timing mark, move till read first bit of resistance)....

Static ignition timing with ohmmeter should be to indicate when point contacts first separate, which should be when the F mark aligns with the case mark.

Typical F marks look like these:



Good Fortune!

Could try spraying starting fluid into carb intake while attempting to start the engine, and see whether the engine will run for a moment.

Good Fortune!

It it still a weak, tiny spark?

Patton wrote: It it still a weak, tiny spark?

While better than it was, it is still not good as it should be.
My chevy has a better spark And that is what I judge by.
This park is blue And bright But not as fat and intimidating as I would expect it to be.

I have tried starter fluid and can smell it burn. I did get a whoof but not a pop.
I remain convinced that I have an electric issue or perhaps timing.
How would I go about finding the possible cause of a weak spark?

And thank you for the pictures. It was nice to see I did it right. The pics and steps in my manual were a bit hazy.

ElSombreroNegro wrote: ...How would I go about finding the possible cause of a weak spark?...

With engine off and ignition switch ON, would first measure voltage received at coil primary, which should ideally match voltage measured across the battery terminals.

This will indicate whether sufficient voltage is reaching the ignition coil.

Good Fortune!

Check this.
Every DC circuit has two ends + & -, so put your voltmeter + lead on the red primary wire, then the - lead to ground. As Patton says close to Batt volts should be attained. Now move that - lead to the wire going down to the points disconnecting it at the coil. So one on coil + and the other on the points, for ground when they close. Rotate the motor slowly, when the points close you should again have your Batt volts. This shows the points are making good contact across the two contacts. Now rotate some more, should go to 0 once the points open. See if it bad contact at the points as this is the ground side of the circuit for charging the coils.
Also you say you cleaned the points. What have you gaped them to? The gap = Dwell which is coil charge time. To big of gap and low charge time. I don't have an old Kaw book but maybe .012"? Brass feeler gauge is preferred. You don't want any oil even from you skin on the contact faces. When final cleaning after gaping, use a white business card. Close the points by turning the engine, then open the point with one finger and slid the card in. Let the points close against the card, then pull it through. Do this till it comes out white still.

Ok, I will try that. I may just get new point set too.. I already got everything else ..

I have the points set at .034, could swear that's what fsm said but I will double check ..

I was hoping to get it close enough to kickstart but I am tired of kicking and will just pick up a battery.
That will be better for the testing anyhow.

ElSombreroNegro wrote: Ok, I will try that. I may just get new point set too.. I already got everything else ..

I have the points set at .034, could swear that's what fsm said but I will double check ..

I was hoping to get it close enough to kickstart but I am tired of kicking and will just pick up a battery.
That will be better for the testing anyhow.

Points set at .014". A spark plug gap is .034".

If not already changed, a bad condenser causes a weak spark. Also a bad coil.

Problem finaly solved, Thank you all for the help. It was the battery, and I have it running finally!

You didn't understand what Loudhvx said (although it may not matter).
He was not talking about the way the advancer bolts to the crank, he was talking about the rotor on the advancer, it slides right off the advancer shaft and can be slid back on 180 degrees out.

Most of us twin owners have done that at least once.

Take the bolt off the end of the advancer, spread the weights a little bit apart, and pull on the rotor, you'll instantly understand.

You posted while I was typing :laugh:

Congrats!!