1979 gs850g suddenly sets out on cylinder 1 and 4

[Jakobzen]

Hello Mighty Forum!

My 1979 gs850 is suddenly only running on cylinder 2 and 3. It happened during a ride. I managed to limp it home. I have cleaned the carb and checked the wiring. Nothing seems to have come loose. I can start the engine on two cylinders, but it lacks all power, so I cannot ride it to my mechanic.
question: is it possible that a fault in points and condensors can cause this problem? When I remove the cover, i can see a spark at one of the points, but not the other, unless I prod it lightly with a screwdriver. However, it doesnt begin to run on more cylinders if I do.

happy Easter to you all!

[zed1015]

Cylinders 1 and 4 are fired by the same coil ( as is 2 and 3 ) so losing 1-4 is almost certainly due to a fault in the associated wiring, ignition coil , condenser or points that serves those two cylinders.

[Big T]

The spark you're seeing means that condenser has failed.

Time to replace both sets of points and condensers, or, better yet, swap in an aftermarket electronic ignition, like a Dyna S.

[Redman]

If you lost cyl 1&4, yes, suspect ignition as one coil and one set of points/condenser operates spark for 1-4 (as others have said).

yes, can suspect condenser failure. As a test, you can disconnect the condenser from the points for 1&4 and see if those plugs start firing.
condensors do fail (more than coils) so those are usuall suspects.

[Jakobzen]

A big thank you to you all - it seems like I have to find myself new condensors and points.

[850 Combat]

You should be able to switch which set of points/coil operates which two cylinders. I've done that to make sure it was the condenser, which it was. OEM points and condenser were high priced.

Todd is correct about the spark though. A good condenser collects and grounds the wasted energy that is created in the coil when the points open and the high tension side of the coil releases its energy.