CDI problems

[red bandit]

My 1980 GS550E has a puzzeling problem, it runs great for about 10 minutes then it shuts down like you hit the kill switch. Then it won't start again for several minutes, not so much as a sputter. When it does start again it fires up on the very first turn,no hesitation. I have eliminated fuel starvation and other common guesses. I think I am dealing with a bad CDI box that shuts down when it gets hot. Any one with any ideas? Any one with an extra CDI box?

[t3rmin]

If it shuts down like you hit the kill switch, with no gradual stall or hesitation beforehand (or erratic idle), then you may be right, except these bikes do not have CDI. What you're referring to is called the ignitor and is a component of the factory electronic (non-CDI) ignition.

A relatively cheap and super easy way to eliminate the crappy stock ignition as a point of failure is get a Dyna S aftermarket electronic ignition. You'll find a ton of info on the Dyna S if you search around the forums. They sell for about $120 at z1enterprises.com if you keep your stock coils.

[jimcor]

Any one with an extra CDI box?

Still available from Suzuki, $373.16 from Alpha Sports.

[t3rmin]

Ick. Dyna S much cheaper, more modern/reliable, and easier! ;-)

[jimcor]

I have eliminated fuel starvation and other common guesses.

Are you sure it's not the petcock? They've been known to act just as you describe your problem.

[arveejay]

Sounds like failing coils. My 850 did just that when I bought it and I found out someone had replaced the coils with the wrong coils right before an extended storage.

[DickV]

Ignitor check

I suggest a relatively easy way to check your ignitor. The ignitor momentarily switches one side of the coil primary to ground when it gets a voltage spike from the signal generator. The other side of the coil primary has a +12 volt applied whenever the switches are in position to run the engine. Use a DVM set to AC volts (on the next scale above 12 volts) and connect the DVM leads to the two wires coming from the ignitor which go to the coil; again, one will be +12 volts and the other should be switched to ground by the ignitor if it is working. When cranking the engine, if the signal generators are working, and the ignitor is working, you will get some readings on the DVM as the ignitor switches to ground. The actual voltage readings are not important, but any voltage reading indicates the ignitor is switching the coil primary to ground as it should. On my GS450 I had to remove the seat and tank to get to the connectors near each coil. Good luck!
DickV