Spark, no spark.

[Superfly]

Hey guys. been down with electrical problems lately. traced down the wiring diagram, and my bike is wired ok. all electronics work well, except the disapearing spark. now you see it, now you don't! I do not have a spare ignitor box yet, any other clues?

[skreemer]

without knowing your bike and not knowing if it's the ignitor I'd check your "signal generator" on the right side just in front of the clutch basket cover. it's a rotating metal mass with two stationary magnets 180 degrees from each other. My bike was having a reappearing dissappearing spark issue and it was the signal generator... inexplicably the magnets got demagnetized... for my bike it can be bought for 19$ off ebay... I had a spare bike to pull it from...


I don't know a good precedure to test the signal generator so I just replaced mine.

then again if your bike is pretty old it might be the points...

[Billy Ricks]

This is for an '85 700 but you can probably use the same tests for your bike.

Here's how to check the ignitor. Remove spark plugs 1 & 2 and ground them to the motor so they will fire when they get power. With the ignitor facing you, the plug on the right side of the ignitor is where the signal generator plug fits. The two terminals on the right side of that portion of the ignitor will be pin 1 at the front and pin 2 at the back. The two left pins will be pin 3 in front and pin 4 at the back. Turn the ignition switch on. With a multitester set a the X1 ohm range put the + probe on pin 2 and the - probe on pin 1. Plug number 1 should fire. Next put the + probe on pin 4 and the - probe on pin 3. Plug number 2 should fire. If this happens the ignitor is good and the signal generators are suspect.


As for testing the pickups, signal generators, measure the resistance between the two wires on each pickup. You should get somewhere around 130-200 ohms. If the resistance is infinity or less than spec they are shot.

To test the coils put one probe of the multitester on each of the terminals on the primary side of the coil. You should get 3-5 ohms. Check the secondary windings by placing one probe into each of the plug wires coming from one coil. Those would be 2 & 3 from one coil and 1 & 4 for the other. You should get 30-50,000 ohms for stock coils and 15-20,000 for aftermarket.

[Superfly]

Thanks for the help guys, I guess I should mention that it is a 81 GS450S! If that helps any. But signal generator sounds like a great place to start!

The part that was getting me is when there is spark, it is a nice bright blue arc. It looked strong. but then... nothing.

[skreemer]

exact same thing I was going through... spark for 20 - 30 minutes... and it was beautiful... button her up and about a mile and a half down the road... nothing... got fed up and change the ignitor box... that didn't make a difference... the only thing on that circuit on my bike was the coils the ignitor and the signal generator... the coils tested good... so I replaced the only thing I hadn't...

[Superfly]

Ok, This is interesting (nice way to say aggrivating!) I think I have narrowed the problem to the wiring in the back left cover.

What happens is when I loose spark, I shake wires on left side of bike, and the spark comes back. I was riding down the road, and she would start spittin' and sputterin' then I would get home, situate the wires better, and get the spark back. and test it again, then have no problem. It is in and out. I need to double check all the wiring in the back, I noticed a split in a wire, fixed that, and it is still doing it.