Need help, please...

[Anonymous]

Hi, I'm new to the site and I just have a question regarding a 1980 gs750.
A friend of mine just bought this bike and it did not start. After testing the coils we came to the conclusion that the coil for #2 and #3 was bad. We replaced it and still no spark on 2 and 3. There is good spark on 1 and 4.
the guy he bought it from told us it's probably the pickup coil for 2 and 3. Is this most likely the case or is there something else we should try first?
We thought it might be the igniter box or cdi box or whatever it's called but we were told if that was bad there would be no spark on 1 and 4 either.

What should we do? Oh, by the way we're looking for a cheep fix to this problem if that's at all possible.

[Anonymous]

Have you verified that you have primary power to the 2-3 coil?

[Anonymous]

Sorry, I'm new to this bike stuff, what do you mean by primary power? I'm not really sure how the whole system works.

[earlfor]

When sitting on the bike the 2-3 coil is on the lright side. Electrical power to the coil is positive + . there will be a orange and white stripe wire that is 12 volts Positive. This is the positive power feed (input) to the coil. The other small terminal on the end of the coil is 12 volts positive + output and this wire feeds the signal generator. Take a multi meter and check that you have 12 volts going to the coil and 12 volts leaving the coil. If you do not have positive voltage output, then there is nothing to power the signal generator/ignition for cylinders 2 and 3.

Earl

Sorry, I'm new to this bike stuff, what do you mean by primary power? I'm not really sure how the whole system works.

[Anonymous]

I'm not sure, I'll have to check tomorrow. If there isn't what does that mean? And If there is what does that mean?

[earlfor]

If you have 12 volts going into the coil and no voltage coming out of the coil, it means the coil is no good. If you have voltage into the coil, and coming out of the coil and the wire from the coil to the ignitor unit is carrying voltage, it means the problem is with the ignitor unit or if that tests to be good, the induction pickup on the crank could be faulty or possibly far out of adjustment.

Earl

I'm not sure, I'll have to check tomorrow. If there isn't what does that mean? And If there is what does that mean?

[Anonymous]

Ok... I know the coil is good. How do I check to see wether it's the igniter or the pick up? And if it happens to be the pickup how is that adjusted if at all.

[Anonymous]

JUst woke up and checked for power at the coil and yes there is primary power. Now what? Are there tests I can do to check the igniter and pickup coil? It's got to be one ot the other now I just need to know which one.

[Don Lobacz]

Ajax,

To test the electrical, you should pull the sparkplugs and lay them on the head (grounding) plugged into their respective wires. Turn the motor over and see which set of plugs fire.

To test the coils, you switch the pair of wires at the coils and turn the motor over. If the same plugs fire, the non-firing coil is bad.

Testing the ignitor and pickups: the wires coming from the pickups are the key. There are either one or two common wires to each pickup (black?) that power them, but the important part is the distinct colored wire from each pickup (output). These distinct wires need to be switched, and there are 3 ways to do it: switch the wire spades going into one connector body, unplug the connectors and make jumpers to make the switch, or cut and temporarily switch the wires. After this has been properly done, turn the motor over and see which plugs fire. If the same plugs fire, then the Ignitor or a wire in the pigtail are bad. If the other plugs fire, then a pickup or a wire in it's pigtail are bad.