left cylinders not firing

[Guest]

hello, newbee here, just got a 1977 gs 750, had it out cruising round town yesterday and it seemed to run fine. today it doesnt want to idle or stay running, seems like the left side isnt firing, both pipes stay cold, blowing cold air out the exaust. i pulled the outside plugs and there black havent pulled the inside ones yet, going to get a longer socket, wondering if it could be a bad coil?

[GelandeStrasse]

Welcome.
It's probably just a bad connection to the coil. Try connecting the left coil +ve directly to the +ve batt terminal and see if that helps

[maddoghoek]

cool, ill check it out . man i really go riden today!! thanx

[JTGS850GL]

Correct me if I'm wrong, but I thought the coils were 1,4 (outside) and 2,3 (inside). A failed coil wouldn't cause both cylinders on one side to not fire.

[GelandeStrasse]

Correct me if I'm wrong, but I thought the coils were 1,4 (outside) and 2,3 (inside). A failed coil wouldn't cause both cylinders on one side to not fire.

Good point!
Oh dear, probably carbs then. Still, good to check coils anyways.

[MisterCinders]

Good point!
Oh dear, probably carbs then. Still, good to check coils anyways.

Check the "Bike Won't Start" thread below.

Dropping 1 and 2 does not sound like electrical, because those split between 1/4 and 2/3.

Of course, do all the maintenance updates (valves, carb strip/dip, etc.).

Check the plugs on the left side again. I wager they are dry for lack of fuel, unless your carbs are fully crudded up.

Also add your location to the profile, someone nearby might be able to help you, and add your bike to your sig, for future posts.

[maddoghoek]

welp i guess i m cleaning carbs, was hoping to save that for a winter project but oh well, just blows my mind that it could run like a champ one day then run like crap the next day

[JTGS850GL]

Join the crowd... Same situation with me. Hope yours turns out to be an easy fix.

[maddoghoek]

have a bit of an update i pulled the plugs off my 750, cleaned them up real good and fired it up and now the two center pipes are staying cold and its blowin some white smoke out the left pipe, probably still a carb issue right? wonderin if i got some gummy crap floatin around in there considering its only been on the street a few times this year. not trying to bug anyone with dumb ?s just thinkin out loud

[MisterCinders]

have a bit of an update i pulled the plugs off my 750, cleaned them up real good and fired it up and now the two center pipes are staying cold and its blowin some white smoke out the left pipe, probably still a carb issue right? wonderin if i got some gummy crap floatin around in there considering its only been on the street a few times this year. not trying to bug anyone with dumb ?s just thinkin out loud

Check threads below in sig. Cold center cylinders could be coil or timing, both are split across 1/4 & 2/3.

[maddoghoek]

update no. 2, went and bought new plugs, fired it up and is running on all four cylinders, all pipes are hot, got a fresh new burn on my knuckle to prove it.seems to be running rich, got alittle black smoke out the exhaust, maybe some carb adjustment next. sound about right?