78 gs550 points/timing issue

[jrom3897]

Hello,

I have a 78 gs550 that was left sitting for a while, I cleaned the carbs and got the bike running although once pulled on the throttle the bike died. I then noticed that only cylinders 2,3 were firing and not 1,4. I assumed this was a timing issue and set the points and the bike began to run normally, but after about 20 minutes of riding the bike died and the same issue of only two cylinders firing started again. I replaced the points and condensers and i'm still having the same problem.

Any ideas? could I just not be setting the points correctly? this seems to have been an issue with the bike's previous owners because most of the screws holding the points and the plate are very worn.

[Suzuki_Don]

Hello,

I have a 78 gs550 that was left sitting for a while, I cleaned the carbs and got the bike running although once pulled on the throttle the bike died. I then noticed that only cylinders 2,3 were firing and not 1,4. I assumed this was a timing issue and set the points and the bike began to run normally, but after about 20 minutes of riding the bike died and the same issue of only two cylinders firing started again. I replaced the points and condensers and i'm still having the same problem.

Any ideas? could I just not be setting the points correctly? this seems to have been an issue with the bike's previous owners because most of the screws holding the points and the plate are very worn.

You have one coil that fires cyl 1 & 4, so I would suspect the coil could be breaking down. When this happens again, swap the coils and see if the fault then transfers to cyl 2 & 3. If it does then the fault is in that coil. You dont have to physically dismount the coils and swap them over, just swap the wires from the points on each coil (black & white) and swap the HT leads onto the opposite plug pairs and then test. If the problem does not swap to the other cyl (2&3) then it is in your wiring, points, etc. that is tied to cyl 1&4.

[tkent02]

could I just not be setting the points correctly?

Could be. What method did you use to set them?

[btbarb]

..... I assumed this was a timing issue and set the points and the bike began to run normally, but after about 20 minutes of riding the bike died and the same issue of only two cylinders firing started again.

If you set the points and it drove normally, but now doesn't, check the point gap on the 1&4 point set and see if it is still set the way you left it. If the gap has changed, I'd say your set screws aren't staying. Make sure your ignition and condenser connections to that point set aren't moving and grounding you out too. If they gap is still good, then Suzuki_Don's coil suggestion.