Poor idling now won't start. Need Advice.

[Anonymous]

If I rev my '81 GS550T even the slightest bit in neutral or with the clutch pulled it will die on me the next time I come to a stop. If I'm very careful not to give it any extra gas it will usually idle okay. Carbs were professionally cleaned 2 months ago when I bought the bike. Any advice? Today it wouldn't start. Weather was slightly cooler. Looked at the plugs and they were dull black. Replaced the plugs and it still won't start. Air filter is clean. Tried the spark test on the block case and got a weak white spark. Once today when I tried starting it I held the starter for 6 seconds and when I released it the engine almost started. Battery is only 2 months old. Plenty of gas in the tank. 12k miles on engine.

I'm new to motorcycle maintenance so any advice is much appreciated.

-Shelby

[isaac]

Check for a sticking choke. Are the jets stock or are they bigger?

[KEITH KRAUSE]

Re: Poor idling now won't start. Need Advice.

If I rev my '81 GS550T even the slightest bit in neutral or with the clutch pulled it will die on me the next time I come to a stop. If I'm very careful not to give it any extra gas it will usually idle okay.
-Shelby

Please describe the problem differently. I don't understand it the way you've described.
Giving it a little gas causes it to stall at the next stop? But you must have given it throttle (without stalling) to get to that point?
Also, any mods or stock? Did the bike just start doing this suddenly, or did it come from the mechanic this way? If the plugs are dull black (the insulator) then it's rich or a weak spark.

[Anonymous]

I believe everything is stock on this bike. I charged the battery and got it to start. About the idling: The bike seems to die on me about 50% of the time when idling at stoplights. I notice that if I've given it gas while in neutral (or with the clutch pulled), say at an earlier stoplight, it is more likely to die at the next light. Should I try adjusting the idle or does the fact that it's burning rich indicate it's a something more involved?

[Anonymous]

Check your coils and igniter box, since you have a weak spark i would suspect those are breaking down. IF so replace them with some accel super coils. replace the box too if needed.
checking things on a bike is a process of elimination. buy a good repair manual and get used to doing this at times. also keep checking GSRESOURCES for help.

[KEITH KRAUSE]

Not knowing the bike's history, it could be so many things. Since you say only a low idle/stalling is the only symptom, we'll focus on that.
We do know the filter is clean and you have new plugs. I assume you have a manual or info to correctly gap the plugs and you bought the correct heat range?
Try a few simple things first. Take off the battery terminals and clean them well. Add distilled water if needed. Check your airbox for good sealing. Set your idle to about 1,100 rpm's or what your manual calls for by adjusting the idle adjuster knob. Test.
If no change, try adjusting the mixture screws IF their tamper caps have been removed and any factory sealant is disturbed. Use a GOOD fitting tool. Keep a record of any changes. Since your plugs are black, try turning them an additional 1/2 turn IN from where they are now. Test. If you like, try another 1/2 turn in and test. We have no way of knowing where they initially are if the caps were removed, unless you LIGHTLY bottom them and count as you go. They are generally 1 1/2 to 2 turns out on stock bikes. I suggest moving them only because the PO could have them too far out (rich) and if you don't like your screw adjustment results, you can always just put them back, following your records.
If the bike still won't idle well, you can try more involved cleaning of the electrical connections at the plug caps, the coils, etc. Also, a carb vacuum synch may help. The carbs pilot circuit may be dirty and the carbs may need a cleaning/rebuild.

[Anonymous]

One more easy check would be the resistance of the spark plug caps ( I am not sure of the spec right now. My newer NGK caps are 4.5 ohm, I think) Too high would be bad. Also the supply voltage to the 2 coils ( it should be close to your battery voltage) Also make sure that the correct wires are going to the correct plugs. What is your battery voltage at when fully charged? I'm adding this because this was my fix recently. Also when you get her fired up check the charging system. With it reved up it should charge up to 14 volts.