'82 GS850L Stalling problem

[Guest]

Would appreciate a concensus of ideas here to get me back on the road asap. Just got bike back from mechanic after 8 yrs in storage. Carbs, forks, battery, brakes,etc all done. Ran like new first couple of days. Tonight after about 1/2 hour to 45 minutes of steady 40-60 mph running, stalled 4 times at traffic lights. When I got home, with the engine running, pulled each plug individually (1->4 from left to right while sitting on bike). Plug one pulled- ran rough, then re-installed; plug 2 pulled- stalled out immediatley; plug 3 pulled-ran rough; plug 4 pulled stalled immediately. Bike normally idles smooth at 1000-1100 rpm but tonight was in the 400-500 range when I stopped at these traffic lights, then stalled on acceleration. Any specific ideas what might be wrong. My wife thinks the coil could not be providing enough spark...is this possible since the bike sat for 8 yrs in my garage, then the coil decides to crap out on me the first week back? Any other definite ideas with these specific symptoms?Any suggestions would be greatly appreciated.
Thanks.
Larry
"The Rocketman"

[GS850_Coug]

Check for vacuum leaks on intake. Spray wd40/carb cleaner/starter fluid on all intake exterior surfaces of intake a little at a time. Listen for any changes in idle. Changes in idle would indicate a leak in the area sprayed. Also check fuel filters. Could also be a bad ground somewhere, resulting in a weak spark. Does the bike start right up? If not, does it sound like a weak battery? If the battery is weak, the charging system may not be doing its job.

[Rocketman]

Battery is brand new. Only electrical thing changed since I got the bike back from the shop was adding a new battery & replacing original H4 bulb with Sylvania Silver Star. I can't imagine that causing a problem at all. There is no fuel filter to check on this model. And why was bike running perfect first few days, and crappng out now? Any indications based on pulling plug results? Also, problem is intermittent. Doesn't stall every time I come to a stop, but often enough to be very annoying and dangerous. Lastly, bike starts right up after stalling. Thanks.

[frosty5011]

You just started a new thread about where to buy replacement coils.

I really doubt that's your problem....both coils going like that at the same time, and only one lead per coil.

You say it ran like new the first few days. How long were you actually running it those days? Were they just short runs, and the first long run (of 30 to 45 minutes) is when the problem first appeared?

Take a look at the colors of the plugs first and let us know.

[Rocketman]

First couple of days were relatively short runs, and yesterday was definitely a longer run. Will pull all 4 plugs when I get home from work later, and will report back. Thanks again.

[Rocketman]

OK Frosty-I'm back...
I did what you suggested-pulled all 4 plugs, which were installed brand new last week. They're all clean as a whisltle, little white residue, but look perfectly fine.
Went on a quick 20 mile round trip, topped out at 65 mph, no stops along the way, and as soon as I did stop, RPM's went from the normal idle of 1000 down to 4-500, and stalled on acceleration. Started up again with no problem, just had to feather the throttle a little til I got rolling. Pulled plug wires individually again (so I always had at least three wires connected) when I got home, and this time, 2&4 stall the engine, while 1&3 have little effect, just shooting quick shocks up my arm? Still think I'm looking at both coils intermittently dying, or not? I can always ask the BikeBandit guy tomorrow, but I just don't want to waste the $$$ through process of elimination, in case I can get a definitive answer from you guys. Thanks.

[frosty5011]

If the bike is running fine (on all 4 cylinders) the entire time that you're riding, and none of the plugs are wet with fuel or fouled, I don't think the coils are the issue. It appears the only time that you have a problem is when you stop the bike......and the idle speed tends to drop down to the stalling point.

My first guess would have been the set-up is too lean, especially with the new info that your plugs have "white residue". I'd richen it up and adjust idle to around 1100/1200 rpm's to see if any change.

[Rocketman]

Will do.......especially since turning a few screws costs a lot less than buying two coils, which I might not need. Is your thought process that by running too lean, engine is overheating, affecting the idle? Think since my mechanic got me this far, I might leave it up to him to make the adjustments this week, especially since by the time I bring him the bike, it'll be nice and warmed up, and hopefully will stall right in front of him (unlike the toothache that magically disappears as you pull into the dentist's parking lot). I appreciate the advice and the call earlier, and will update you during the week. For now, I sit home, polish chrome, and wait for Tuesday as my mechanic is closed Sunday & Monday.....

[GS850_Coug]

Running lean is another reason to check your intake for leaks also. Make sure not to just adjust the carbs to fix the symptoms, as the more likely problem is bad orings at the head/boot interface and/or fuel filter issues.

[Rocketman]

I'll check for intake leaks as suggested, but I've looked all over and really don't think this bike came with a fuel filter. If you have the same '82GS850L and can let me know where it is, I'd appreciate it, but I've had the tank off and traced all the lines and can't find a filter (in-line or other) to save my life.

[steely]

The only filter on your bike is the screen on the petcock.

[Rocketman]

That's what I thought. Thanks.

[flyingace]

If your bike is warmed up and idling at 400-500, what happens when you set your idle adj screw up to 1100 or so? Does that cause 'normal' to be too high?

It's possible that your 'normal' idle is just the throttle sticking slightly and not hitting the stop on the idle adj screw.

I had a problem with idle dropping suddenly, but it was always because one spark plug was getting fouled.

[Rocketman]

Normal idle is 1000 to 1100 rpm. Just lately its dropped down to 4-500 only after riding for 1/2 hr to 45 minutes. I think if I reset the idle to 1100 after the bike was warmed up, it would idle in the 1500-2000 range when cold, which is WAY too high. Throttle response is fine, and doesn't seem to be hanging up at all. Lastly, no plugs are fouled-they're completely dry. Tomorrow mechanic is back, and I'll leave it in his hands. He brought this baby back from the dead after 8 years, and I'm certain he'll find the problem (especially since I still owe him $$$$ for all the other work!) But thanks again for all the suggestions. Half the folks seem to think engine's running too lean, other half thinks both coils are intermittently dying. I'll let you know as soon as I get an answer from the mechanic this week (I hope!)

[Rocketman]

Hey Frosty.....You out there?????

Just as a follow-up to our last conversation, I think I have some good news. Brought my bike to the mechanic yesterday, explained my stalling problem, and discussed all the possible solutions you GS-ers offered. He took the bike out, went up to 8K rpm's in 2nd gear, came back with a fully warmed up bike and it was idling perfectly at 1400-1500 rpm. He claims that even though carbs have been rebuilt and synced, and even though tank was shiny clean as a whistle inside, all it takes is one thin hairline piece of shellaqued (?) gas clogging up a jet, or one old piece of carbon laying around for the past 8 years to screw things up. He asked me to be patient, get 300-400 miles under my belt since the rebuild, and to blast the bike out once in a while 'til then to bust loose any old sediment to be burned up and blasted out the exhaust. He says bike naturally should idle 1000-1100, and 1400-1500 when smokin hot at idle, and that's just what its doing now. \\/ Guess I just never had much cause to run at redline, mostly just cruise at 3-4000. Still waiting to get bike back later this week with new s/s braided brake hoses, then time to hit the road again, and hopefully not to stall again. Will update as we progress.
Rocketman