KZ440 Pickup Not Detecting Timing Rotor

Hey folks, back at it again with the 440. It always seems to be something with this one...

On my 81' KZ440 LTD with the electronic ignition, I've been having trouble getting it to start. Once it would start, however, it would run just fine. Today, I went to start it and it was seriously having a hard time starting. No popping or anything. I pulled a plug and noticed I wasn't getting any spark when I turned the engine over with the starter.

BUT (and here's where I'm stumped) if I tapped a screwdriver on the pickup magnet with the plug grounded to the engine, the plug would spark very well. A nice, clean, fat spark too. Then I would try again with the starter (plug grounded the same way to the engine) and it wouldn't spark at all. The advancer opens just fine (I've taken it apart, cleaned, and lubricated it in the past year), and I'm fairly confident it's on correctly because it runs very well once it's started. Also, the battery is very new (within the last month), its charged properly, all the lights work, and the starter turns over at a good speed.

One last thing: I've noticed that if it is having a really hard time starting, I can usually bump start it. I have no idea why.

There are a few possibilities.

The pickup and rotor are a tiny little generator for the ignition signal.

Sometimes the starter turns the motor too slowly to generate a fire signal at the pickup. Bump starting might rotate it faster.

Check the gap between the point of the rotor and the center pole of the pickup. It should be about 1mm. Less than .5mm is too close and could cause the rotor to contact the pickup.

The more likely cause is voltage loss through bad switch contacts or fuse holders or wiring. When you use the electric start, it reduces the voltage even more, and then the igniter and/or coil won't have enough voltage to work. With clean switches, connectors, and wires, this should not happen. The fuse holders are the most likely place to lose voltage, then next is the kill switch, then the ignition switch.

To test this, you run a jumper from the battery's positive terminal to the coil's positive connection (yellow/red wire). This jumper will also turn on the ignition permanently, so don't leave it in place. Then start the bike with the starter. If that fixes it. then you have a little maintenance to do to restore the wiring.

Unplugging the headlight might also give you just enough extra voltage at startup.

Okay, so I got around to trying both of those methods and here's what I found:

I ran a jumper from the positive coil contact to the battery, but that didn't work. It did turn the ignition on permanently, so I know that I did it correctly. However, it still didn't start the bike, so I disconnected it.

Next, I took a look at my pickup gap. Low and behold, the gap was 1.5-2 mm! How it got so spaced, I have no idea. But, I sorta bent the pickup closer to the rotor until it was barely more than 1mm, and the bike started like a dream. After all the things I've adjusted before fixing this, the bike now starts better than it has ever started for me. Any idea as to how that gap increased on its own like that? Seems like its not something that should get out of adjustment on its own...

Thanks so much! Didn't know if I'd ever get this thing to start well. Now just to work on adjusting the new vm30's I got in the mail.

The most likely cause of the pickup to move would be for the rotor to strike it. If you look at the tip of the rotor you will see scrape marks if that was the case. There is no official adjustment for it, but if you loosen the screws you can move the pickup assembly a little bit. If the screws were tight, then it was probably set where it is.

So then why would it become harder to start?

There are several possibilities as mentioned above. Moving the pickup closer increases the signal. Raising the voltage to the igniter *might* increases the signal. Or maybe a part is starting to fail inside the igniter and is causeing less sensitivity to the pickup signal.

If the pickup reliably starts the bike at 1mm, then I don't think you have too much to worry about. Just inspect it every once in a while for damage (scrapes) on the rotor tip. Under more stressful running (hard acceleration etc) the crankshaft can bend which can cause the rotor tip to possibly contact the pickup.