I guess Murphy is alive in my garage

[Guest]

I bought two GS850's a month or so ago. I've rebuilt the carbs and got around to rebuilding MC's and calipers today. So I thought I'd take the L for a ride. Was I disappointed... Well turns out only running on 2 and 3. So first thing I did was pull the plug caps off of 1 and 4 and measured resistance between spark plug caps... Wide open. So for a sanity check I measured between 2 and 3 and got about 12k ohms. Then I went to the other GS850 (not running yet) and same resistance readings. What are the chances I have two 850's with 1 and 4 plug wires with no continuity? Well it's getting late so I'll trouble shoot tomorrow but I'm pretty sure the caps are no good or the connection to the plug wires is/are corroded. I did remove the resistors and they each measure 12.1k. But I did not unscrew the caps yet.

I've heard that the OEM coils are pretty robust and rarely go bad.

[fastbysuzuki]

first i would take off the plug caps and cut around 1/4" off the leads to expose good/clean cable and screw the caps back on and give it a try if that fails buy new plug caps as the resisters in the caps may be bad. both ideas will cost you very little money its a matter of working through untill the fault is found.

[tkent02]

For fault finding you can just replace the resistor with a piece of wire. Some of us even leave them in permanently.

[Redman]

.
. I did remove the resistors and they each measure 12.1k. ..

THey? the resistors? the coils?

THe resistor caps should be about 5K. THey go much higher as they go bad.

I think the purpose of the resistors is so the ignition system doesn't create radio frequency noise on nearby peoples electronics.

.

[Nessism]

Agree that the coils are robust. You can even dig the wires out of the coils and replace them, contrary to what some may think.

[chuck hahn]

No need to replace entire caps. If you want to do away with the resistors ( in stock caps ) just unscrew the connector inside and dump the resistors out, replace with 1/8 inch copper or brass rods cut to length of the resistors and reaseemble the caps. I do this automatically on any bikes i get to just eliminate the potential problem of failure.

[jdvorchak]

THey? the resistors? the coils?

THe resistor caps should be about 5K. THey go much higher as they go bad.

I think the purpose of the resistors is so the ignition system doesn't create radio frequency noise on nearby peoples electronics.

.

Yes I pulled out the resistors and measured them. Each reads the same about 12.1 k Ohm.

Like I said I'll work on this tomorrow but thanks for all the replies and confirmation that the OEM coils are robust. I have replaced those resistors with large gauge copper wire and even used a brass screw once. This particular bike has a radio mounted in the fairing but since I only listen to FM I doubt that spark RFI will be a problem. I'm guessing that since they are the outside cylinders, they probably are exposed to the elements more and probably only corroded plug wires is the problem. I just thought it was funny that both 80 and 81 GS850's had the exact same problem! Well they both had to have brakes completely rebuilt and the carbs as well so this shouldn't surprise me....LOL