TOPIC:

Well this chump is stumped!

Rode my 79 kz750 twin to work and parked it outside for a few weeks (we were in the middle of moving). It was running great when parked. When I tried to start it to bring it to our new place it wouldn't start. Towed it home and I've got no spark on either cylinder.

Spark plugs are brand new
Battery is producing 12.8 volts
I have 12.8 volts at the coil
Coil is aftermarket, 2-3 years old
Primary and secondary windings check out ok per tests in manual
Point gap is correct
Points look fine (no pitting)
Wire between points and coil has continuity

I'm not seeing any spark at the points when I try to start the bike. Seems like I should see that right?

Bike was running great when parked three weeks ago.

The only other thing I'll throw out there is that when parked bike was kick start only. I had a rebuilt starter and starter clutch waiting to go into the bike when I parked it. When it failed to start and I towed it home I started by putting the starter motor and starter clutch in.

This chump is stumped. Any ideas?

Have you checked continuity thru the coils?
What brand coils do you have?

Lazyman06 wrote: Have you checked continuity thru the coils?
What brand coils do you have?

I don't remember the brand of coil. It's been a few years. I ran the tests on the primary and secondary coil windings outlined in the manual, the ones where you're measuring ohms and looking for a short. Both tested OK.

The manual mentioned a test for continuity between the red/yellow wire and the coil core. I didn't know what they meant by the coil core. How do I test that?

That's to see if it's grounded internally.
steve

Chump was a derogatory term for a stupid mark by con artists or by low life criminals. You're NOT a chump.
Steve

So how do I test at the "coil core"?

Check each lead against the metal core.
Steve

Make sure your points are not shorting out to ground.

Disconnect the negative leads from the points. Pull a plug wire off spark plug and if you have an extra spark plug, clip it onto the plug wire and lay the plug on the engine case somewhere. Apply 12v to the coil and touch the ground lead from the points on the engine case. The plug should fire every time you lift the wire from the case if the coil is good.

missionkz wrote: Disconnect the negative leads from the points. Pull a plug wire off spark plug and if you have an extra spark plug, clip it onto the plug wire and lay the plug on the engine case somewhere. Apply 12v to the coil and touch the ground lead from the points on the engine case. The plug should fire every time you lift the wire from the case if the coil is good.

OK, by this test the coil seems OK. I cleaned the points and set the gap (for the third time) and still no spark. So I've ordered a new set of points and condenser. My gut says it's the condenser. I've not replaced it in the time I've had the bike. We'll see.

Check the insulators for the points, one or more may have moved or cracked, shorting out the system.

Usually the points will start sparking indicating the condensers are going bad.
Steve