81 GS 650 L one coil not firing

[Guest]

Both coils ohm out exactly the same. The left one fires fine, but the right one....nothing. Where to go from here? Thanks

[tom203]

Both coils ohm out exactly the same. The left one fires fine, but the right one....nothing. Where to go from here? Thanks

Check/clean connections from signal coils up to ignition coils- there's a 4 way plug under seat and a 2 way in solenoid area. Remove/unscrew spark plug caps and cut each plug wire back 1/4 inch to expose fresh copper to cap spike . Remember this is the wasted spark fire system- two spark plugs at same time ,thru one and up thru other.

[Redman]

Both coils ohm out exactly the same. The left one fires fine, but the right one....nothing. Where to go from here? Thanks

Did you "ohm out" thru the caps? (about 30K)
THe caps and/or the ends of the wires at the caps are much more suspect than the coils themselves.

[abaton6]

I checked the coils at the brass connections. So, you're saying "check through the caps", Do you mean from one cap to the other should be 30K? Thanks

[tom203]

I checked the coils at the brass connections. So, you're saying "check through the caps", Do you mean from one cap to the other should be 30K? Thanks

A better way is to remove both plug caps from an ignition coil ,stick your multimeter probes into the plug wires (wire to wire) and measure resistance- this way look for about 12000 ohms. Plug caps get corroded and give erratic readings. New caps will measure from 5k to 10k each.

[Redman]

Oh, I did not explain myself well at all.
Yes, I did mean, also do an ohm check with the caps on the wires, from one cap, to the other cap. So that way you are chacking the cap, its connection to the wire, the wire, the connection to the coil, the coil, the other connection to wire, the other wire, the other connection to the wire, and the other cap. Any one of those can be a problem, in fact I would suspect a cap or connection to the wire more that the coil itself. Total should be about 30K ohm.
Of course though, if the ohms are much more or infinite, that indicates there is a problem, but doesnt tell you where the problem is. TO troubleshoot further, take off the caps and ohm check each one, should be 5K. (with agean use, they go higher, like 10K or 20K and then go complete open). Also Look at the ends of the wires, if the look burnt or if it looks like some/many are missing or if some are lots shorter than others or if you know you havent trimmed them in years, go ahead and cut off about 1/4 to get to fresh wires. WHen measure from wire to wire dont stick the meter leads way up into the wire, do it only about like what the screw point on the cap does. SHould be about 20K.

.

[abaton6]

OK, l couldn't look at it for a while, now I'm back. Thanks for your help. I trimmed the HT wire at the cap end about 1/4", no help yet. I'm looking at the signal generator. My GS650 is an "L". There are 3 wires coming from the S G, but in my Clymer manual, looking at the wiring diagram for the "L", , it shows 2 wires. I took a pic of the S G, and followed the wires to the connector. Two of the wires are in the connector, while the other is not,...this one was cut when I picked up the bike.. Also, is there anything l need to do to the S G, to clean it upDSCN1290[1].jpg?

[abaton6]

3 wires from the S G.

DSCN1289[1].jpgThe three wires can be seen here, but my manual shows only 2

[tom203]

The red plug is the oil pressure sender with its wire (green/yellow?). The signal generator just has the blue wire and the green wire: these travel up to a plug near the starter solenoid and then on to ignitor.

[abaton6]

Thanks Tom. I'll do the coil and wire checks tomorrow. Ever hear of an issue with the signal generator? Also, since l am getting spark out of one coil, l take it that the iginitor is OK?

I found a lot of green corrosion on the wires that plug into the coils,..replaced all the spade connectors.

The red plug is the oil pressure sender with its wire (green/yellow?). The signal generator just has the blue wire and the green wire: these travel up to a plug near the starter solenoid and then on to ignitor.

[tom203]

Disconnect the signal coil plug from ignitor and ohm measure between blue and green wire going back to signal coils - look for around 300 ohms. I'd suspect corrosion issues causing a problem more than anything.
The ignitor could be at fault,with one coil set working while other set didn't . Likely the ignitor has a pair of transistors , so one could be smoked. At one time, I had 5 ignitors and all tested good on my bike. This ignitor seems tough, but a failed charging system could fry it, I sold one to a Florida guy who had this issue.


have a look at the ignitor testing in this link

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html

[abaton6]

Ok, I got back to the garage today. The coil that is firing measures 4.5 ohms at the primary. From cap to cap, measures 0 ohms.. The coil that is not firing measures 4.0 ohms at the primary,...and 36.2 ohms cap to cap.