'82 GS850L Stalling problem

[frosty5011]

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

Glad to hear that it seems to be running better......but I don't quite agree with the above statement. It still sounds to me like it's set up on the lean side - there shouldn't be a 400 rpm difference in idle speed. Keep an eye on your headers....if they start discoloring/turning gold, it's too lean.

[GS850_Coug]

I have to agree with frosty, only with a little curiosity as to why the bike should idle HIGHER after heating up. When you start a cold car, the choke will keep the idle high until it warms up enough to let off the choke. After this, the idle should maintain itself at the proper base idle. If not, then there is a problem with the fuel system, either too rich or too lean. If the bike runs better when hotter, that is typically a lean condition. If it runs worse when hotter then it is a rich condition. Check the plugs and do throttle chops. This will help to identify proper mixture before you have discoloration on your pipes.

[Rocketman]

Will do. Should be picking up bike tomorrow. New s/s brake lines are in, but wrong banjo bolts. Hopefully I can update you by the weekend. Larry.

[Rocketman]

Just in case I can't find you guys on short notice, can you give me the quick low-down on how I adjust the mixture from lean to rich, and how will I know when it's correct without running it for a half hour at a shot, and waiting for it to stall. Thanks again...me.

[frosty5011]

It could be lean for a variety of reasons: missing or un-oiled foam air filter, intake leaks, lean mixture screw settings. If your plugs are bone white, it's too lean, you want a a brownish/greyish plug color. And to do that (check plug color) right, you should do plug chops at various throttle settings.

As far as richening out the mixture, I'd make sure the other things are not the culprit first before messing with those screws. Those are the ones inside little holes on top of the carbs, which may or may not be plugged with an aluminum cap. And definately record/mark exactly how far each screw was turned in (or out from bottom) before you start making changes in case you screw things up and need a reference point on where to set the screws again in order to get it running.

[Rocketman]

Thanks Frosty...and what exactly is a "throttle chop"? Air filter is brand new & oiled; to check intake leaks, am I pretty much looking at the black rubber boots going from the carbs, and spraying WD-40 on them is OK to see if idle sounds/RPM's change? Used to have plugs in carbs, but mechanic drilled them out on the rebuild and installed screws.

[Rocketman]

Hey all...
Just got bike back from my mechanic and still having the stalling problem after 1/2 hour warm-up ride. Idles great when cold (1000-1100 rpm), and runs strong, but first time I stop, idle drops down to 4-500 and stalls upon acceleration. Took all your advice, and found no intake leaks, etc. Someone suggested pulling fuel petcock out and checking screen for sediment clogging, but mechanic says that can't be it, or it wouldn't run as strong as it does. Mechanic will be getting the bike back tomorrow to adjust mixture screws from lean to richer, as plugs are white now, and most of you suggested these bikes ('82 GS850L) run naturally lean, so not a bad idea to richen it up a bit. Also, new sympton after 1/2 hour ride last night, pipes 1,3 & 4 were wicked hot to the touch as they should be, but pipe 2 was not as hot, such that I could actually hold it without burning my skin. Any more ideas? Or how about you all come to Long Island to my house this weekend (I'll supply the beer and chips) and help me fix this puppy before I lose my patience!! \\/

[flyingace]

This sounds exactly like the symptoms of a problem some of us had a while back, only it was the #4 cylinder. The #4 plug fouls, and the idle drops and the bike stumbles from only 3 cylinders firing. Once it got to a certain RPM, the problem would clear itself, only to start at the next stoplight.

If you've ruled out the petcock, I personally believe the problem is related to intermittant flooding of one carb. Most likely due to misalligned float pins keeping the float stuck open.

Here's the steps I would take:
1. Swap plug wire#4 with #2. If problem persists with #2, it isn't electrical.
2. Take out #2 carb and clean, clean, clean every passage. Especially the idle circuits. Replace the entire needle/seat mechanism including the float pins.
3. Put a new plug in #2.

[frosty5011]

You stated that the carbs were cleaned by the shop that you just took the bike to. Right now, I'm going to give the mechanic the benefit of the doubt and assume he gave the carbs a good and proper cleaning.

If the plugs are completely white and dry when you pull them after a 1/2 hour ride, the cylinders are not rich/flooding. If you can hold the header with your hand after a 1/2 hour ride, that cylinder is not firing. It may start firing when you first start up the bike with the choke....but is then cooling off during the ride when the choke is off, and you're running on 3 cylinders.

If certain about there being no air leaks, and the proper filter being installed (and oiled if the foam type), I'd take the bike out, warm it up, and when back in your garage (see that you have the same situation as before...#2 not firing/cool header) give just a slight bit of choke while it's idling (don't look at choke knob, but watch the choke plungers - depending on how much play in your choke cable, you can sometimes move the lever/knob quite a bit before choke is actually opened) to see if #2 starts firing. If it does, then you know that #2 is too lean and the mixture needs to be increased. Once you know that that's the culprit, then I'd adjust each mixture screw richer in small increments until the plugs get their proper color.

And you will also most likely then have to readjust your idle speed to 1100.

[Rocketman]

Hope this doesn't sound silly, but if #2 does start firing, how will I know? Just by feeling the header to see if it gets hot?

Thanks again,

Larry

[frosty5011]

Hope this doesn't sound silly, but if #2 does start firing, how will I know? Just by feeling the header to see if it gets hot?

Thanks again,

Larry

You won't be able to hold the header with your hand like you've been doing!:-D

[Rocketman]

Good point Frosty. Maybe I can get one of my 4 kids to test it for me (since I've got extras)

[Rocketman]

Latest stalling update

Hey Frosty....
Dropped the bike off back at the mechanic last night. Finally, she crapped out right in front of him, and he saw my problem. We ran the bike at idle super-hot, and he has a laser thermometer. Three headers registered about 145-150 degrees, while one was only at 90-95. He's going to adjust idle mixtures on all 4 carbs, but he really thinks its an ignition problem more than a fuel problem now. Under my side cover, there's a little black box with a bunch of wires coming out. Think its some sort of signal generator telling stuff when to fire, or something. Somehow a 1980 GS1100 box ended up in my 1982 GS850! Don't remember putting it there myself, and never had any work done on the bike 'til now, so its somewhat of a mystery. Anyway, mechanic says these thingys do go bad after a while and send weak signals, so he's ordering and installing a Dyna S in the engine side cover to improve the ignition firing, or pickup signal sending, or whatever. Leaving the original coils for now, as they seem OK. Hopefully this will do the trick. I'm into the bike so far for $900 (rebuilding carbs, rebuilding front forks, installed braided brake lines all around, rebuilt front master cylinder, new front pads, new battery, general tune up and fluid changes, new Sylvania H4 bulb, state inspection, and miscellaneous new shiny stuff from Flat Out Motorcycles. Another $200 this week for the Dyna S installed, and I pray its finished. The guys not killing me on price-seems pretty reasonable for all the parts & labor, I just want to stop the bleeding! If all goes well, I'll be back on the road by mid-next week. If all REALLY goes well (and the wife OK's it) maybe I'll see you in West Virginia next year. Close to you, but a hike for me.........

[flyingace]

Sorry, I meant above to swap #2 and #3 plug wires (there went my credability - your bike wouldn't even run!). Anyway, that really is all you have to do to determine if the problem is electrical. If #2 clears up, and the problem goes to #3 - bingo it's electrical.

By way explanation, the #2 and #3 plugs fire at the same time from the same coil, so you can swap them. However, since they do fire from the same coil, that eliminates everything in the ignition except the plug, cap & wire.

[Rocketman]

I appreciate the follow-up. Hopefully with the idle mixtures adjusted and the new Dyna S installed, my problems will be h-i-s-t-o-r-y. If not, I'll start pluggin' and unpluggin' wires until this thing purrs like new.
Thanks again.