Dies at idle

[spots25]

My '78GS400 dies at idle. It won't do it right away, but after about a minute of idling, it will start sputtering and die. I've cleaned, tuned, and balanced the carbs. If I set the idle up higher, it will run like it should, but it obviously idling too high. Any suggestions?

[EZ OUT]

Re: Dies at idle

My '78GS400 dies at idle. It won't do it right away, but after about a minute of idling, it will start sputtering and die. I've cleaned, tuned, and balanced the carbs. If I set the idle up higher, it will run like it should, but it obviously idling too high. Any suggestions?

If the valves have not been adjusted recently, this could be the problem. My bike used to die at traffic lights and stop signs and never idled consistently. I replaced the o rings in the carb manifolds and rebuilt the carbs but it still happened until i did the valve adjustment. Now it purrs.

[spots25]

valves = adjusted like 500 miles ago

[beby99]

petcock needs cleaning?? Float height correct?

[gspaul]

Vacumn leak between the carb and the petcock, or in the petcock it self?

[spots25]

its a gravity feed petcock, that I just rebuilt. I don't suspect float height because it works just fine at any other speeds, just not idle

[IanFrancisco]

If you haven't adjusted the slow circuit screws you might want to. Mine were turned out only 1 1/2 turns and had the throttle stop screw cranked up to compensate. The bike idled at 2000rpm and would only idle at 1200 if I used clutch drag to force the rpm down. Blipping the throttle returned the idle to 2000rpm. Adjusting the slow circuit screws to 2 1/2 turns out and backing off the throttle stop screw solved the problem. The slow circuit screws are near the top of the carbs toward the front and face outward. Mine do not look like they had been drilled to expose them, but on some carbs they are sealed off. On a '78 GS400 chances are they were not sealed. Your carbs may be different from mine, I have the OE Mikuni CV carbs.