GS450T waste spark system pre-ignition on intake causing backfire though carbs

[Guest]

I seem to be having a pre-ignition issue on my bike. I can turn it over and it cough a few times, and a little bit of white smoke slowly rises from the exhaust, however eventually it will backfire out of the carb on the right cylinder and will not start. I've noticed that the right cylinder is the one that is "coughing/pop" every four seconds or so, and the left isnt doing anything, maybe the occasional "cough/pop". It also seems that the right carb is the one backfiring more often than not, but i have seen the left side do it as well, though not as often. I'm not sure whats going on, i had it running on the left cylinder for about ten seconds before my igniter box died, i forgot to put the spark plug wire on the right cylinder, but i have replaced it with another working igniter box and now i get nothing at all. Any help would be greatly appriciated

[Steve]

Mis-firing is not all electrical.

Have you cleaned the carbs and adjusted your valves?

The popping could be a lean mixture that finally has enough fuel in it to fire, or it could be a valve that is not quite closed because the clearance is too small.

.

[sam000lee]

I don't believe there is a waste spark on the GS450 so it shouldn't be firing when the intake valve is open. There's an orange wire supplying power to the coils and white and black/yellow wires (IIRC) coming out of the ignitor sending the firing signals to the left /right coils. Is it possible your timing is off or you switched the coil leads?

[sam000lee]

Mis-firing is not all electrical.

Have you cleaned the carbs and adjusted your valves?

The popping could be a lean mixture that finally has enough fuel in it to fire, or it could be a valve that is not quite closed because the clearance is too small.

.

Also this. My GS450 pops from the carb. every once in a while when I'm sitting at a red light.

[coreyspare]

i was pretty sure the gs450 had a waste spark system, it has two pickups and two trigger/lobes, each spaced 180 degrees apart, so when one trigger lobe passed a pickup coil the lobe on the other side passed the second pickup coil at the same time. it seems strange to me that it would have two separate pickups, but i dont think there is any logic in the igniter box to do a single firing cylinder. What really stumped me is it ran ok for a good ten seconds, but i was never able to get it to run at all afterwards. I know the timing is right, i haven't checked the valve clearances, but even if they were off i would still think i would get it to at least run very rough. Carbs have been cleaned twice now, and there is no manifold or vacuum leak.

[JTGS850GL]

Might also want to do a compression check and make sure you don't have a leaky valve.

[coreyspare]

Well, i'm confused. I switched ignition coils and it ran fine, so i'm assuming it is not a wasted spark design.