Carbon fouling problem

[flyingace]

I don't think this problem is electrical. Sounds to me that the bike could be taken out on the freeway and run at 70 all day long. If the charging system is bad, the ignition system would stumble and stall pretty quickly. However, if a new battery solves the problem - disregard the rest of my post.

This is strangely similar to a problem I had with one carb where the float would intermittantly get stuck in open position due to misalignment of the holding pins. It ran well when wide open, but once in the idle and off-idle circuits - black sooty plug and stalling. If just two carbs have this condition, the bike probably won't run.

Just my .02

Good luck. Sounds like a diagnostic nightmare.

 

[Jethro]

I'm almost certain the carbs aren't the problem. I say that because the bike runs perfect, flawless even until it gets warmed up. Even then all I have is a tiny stutter when I let the bike idle for a while, like 30 seconds. If I blip the throttle, the stumble goes away and it's no problem. I'm not ruling out that the carbs are loading up the cyls with fuel at idle, and I only have an issue when I let it idle for a minute, but wouldn't that happen even when cold? If anything the condition would be worse when cold. Plus the carbs wouldn't be dry carbon fouled, they'd be wet when it sputters.

I'm convinced the electrical is the problem. The battery seems to not have enough life left to hold a charge when it's at idle. When the stator spins a little faster (like when I blip the throttle), the battery gets a temporary blast of juice and makes the condition seem better.

Billy, I did get some new plugs, but the battery needs to charge overnight. We'll see what tomorrow brings!

 

[flyingace]

I suppose that's possible. I'll keep an eye on this thread - your pain and suffering is very educational

 

[Boondocks]

... My new battery is charging. When I got home, I had 12.48 volts at the battery. It starts the bike just fine, but probably only becasue the bike takes about 2 revolutions to fire up (it's running so well). After letting it warm up, I checked the voltage at 5k rpms- 14.5 volts on the money, no fluctuation. However, I let the bike idle for a while after it was warm, and while running at idle (when the stutter becomes present) the voltage was less than 12.3. I'm pretty sure this is the problem. When I get it revved up a little the voltage goes back up. But at idle I have a very weak battery.

Could this also indicate a low rpm charging problem with the stator?

No. It is normal to show some battery discharge at idle. The engine must be turning faster than idle before the stator can generate enough power to charge the battery.

 

[Boondocks]

Can one of you guys also explain an AGM battery to me?

It's a sealed, maintenance free high performance battery with advanced technology. The link at AGM, or Absorbed Glass Mat Batteries explains it better than I could.

 

[earlfor]

I dont think you have a low rpm charging problem. It is normal for the stator not to produce enough to run the bike at less than about 2K rpm. There will always be a discharge condition at the battery at less rpm than that.

P.S. I posted the above from a previous page, now I see Philip already answered. LOL

I still believe you have a marginal battery. AGM is the way to go, but they are more money.
On the other hand, I have not needed to replace my AGM in 4 years and it is still doing fine, so in the long run, it may be cheaper. A really nice thing is never needing to add water. There isnt any place to put any in anyhow. ehehe

Earl

I checked the voltage at 5k rpms- 14.5 volts on the money, no fluctuation. However, I let the bike idle for a while after it was warm, and while running at idle (when the stutter becomes present) the voltage was less than 12.3. I'm pretty sure this is the problem. When I get it revved up a little the voltage goes back up. But at idle I have a very weak battery.

Could this also indicate a low rpm charging problem with the stator?

 

[Jethro]

On the other hand, I have not needed to replace my AGM in 4 years and it is still doing fine, so in the long run, it may be cheaper.

Yep, I go through probably a battery every 2 years if I'm lucky. If you get another year out of yours, it's like spending $120 for me.

 

[earlfor]

I paid about $65 for mine. Not bad, all things considered. It also "rests" at around 12.8 volts or better, so no low voltage quirks either.

Earl

Yep, I go through probably a battery every 2 years if I'm lucky. If you get another year out of yours, it's like spending $120 for me.

 

[Jethro]

It also "rests" at around 12.8 volts or better, so no low voltage quirks either.

Nice, if this cheapie battery solves my problem, I'll buy one of those beauties. The story will continue tonight...

 

[earlfor]

My personal rule for working on a GS is no matter what I think is the problem, the first thing I do is check the electrical system. 9 times out of 10, it isnt the carbs, timing, valves, induction, etc, its connectors, aged wires, battery and low voltage. Without the electrical system working correctly, there is nothing that can be done accurately on an engine if the engine has to be running to do it.

Earl

Nice, if this cheapie battery solves my problem, I'll buy one of those beauties. The story will continue tonight...

 

[Jethro]

Well, no dice. The new battery is charged, rests at 12.7 volts, I lose about a volt between the headlight, tail and coils, is charging fine but when it gets warm, it stutters on take off and still seems to be carbon fouling plugs. All connectors I could find are clean and good. I am supposed to test voltage at the coils between the orange/white wire and the POSITIVE battery terminal, right? Between the NEG battery terminal and o/w coil wire I only get about 8 mv.

I went back into the carbs, and checked the float level with tubes on the float drains. If anything they are a little lean. I put new plugs in and still have the problem. I even got fresh gas. The mix screws show highest idle when at about 1/4 of a turn out form seated (just like last year with the 4-1 system) I am currently dipping another set of carbs and will rebuild them so I have two sets of carbs to swap and test with.

Any more suggestions? Could poor timing do this? A stretched timing chain? Anything electrical I am not testing? Could the coils be bad? Remember, it runs awesome until it gets warm. Even then the only problem is on take off after it sits a minute. It idles and runs like a top. Just a stutter on take off.

 

[BadBillyB]

If you have a prime position on the petcock, put it on prime w/engine off and see if one or more of the carbs overflows within a few minutes. A needle and seat that does not seal quite well enough may cause problems when the fuel consumption is low (idle)........just a thought.....And the "voltage drop" is checked between the B+ terminal of the battery and the coils battery supply while the engine is running...The measurement from Battery Neg to coil B+ terminal is available voltage........BadBillyB

 

[earlfor]

The orange/white wire is positive, so you check voltage between the orange/white wire and the neg bat terminal. If the battery shows 12.7 at the terminals and you have 8 volts at the unconnected coil wire, thats a 4.7 volt drop. Last time I checked, my 1150 had 1/4th volt drop. The six pin plug that connects your ignition switch to the wiring harness is supplied power from the fuse block by two 12v + wires, one is red, the other orange. The other 4 wires are output wires. I would check input/supply voltage on those two wires with a multimeter before they reach the 6 pin connector. Ignition doesnt need to be on because that is before it is switched. Those wires are always hot. If supply voltage is the same a battery voltage, I would turn the key on and check voltage on each of the four output wires. (you can push a straightpin through the wires and clip your meter to the pin rather than stripping wire and making a mess.) I think you need to find out where that 4.7 volts is going. If output voltage from the ignition switch is only 8 volts, I would replace it.

I would unplug the headlight, tailight and coils so there is no electrical consumption and all that is being measured in voltage in the harness.

Earl

I am supposed to test voltage at the coils between the orange/white wire and the POSITIVE battery terminal, right? Between the NEG battery terminal and o/w coil wire I only get about 8 mv.

 

[Jethro]

Ok, between the neg battery terminal and the o/w wire, I get a few millivolts if that!! The positive battery terminal between the o/w wire shows 11.8 volts, with the battery itself showing 12.7. Is there a grounding problem? Is this backwards? I did the test at least 10 times.

 

[earlfor]

The orange/white wire is switched 12v+. There is no voltage on it with the ignition switched off. Ignition on, red meter probe on the orange/white and black meter probe on ground or the neg battery terminal will read voltage on that wire. It should be close to the same as voltage at the battery terminals.

There is a voltage drop, we're trying to figure out where. Power comes from the battery, goes to the fuse block, then into the ignition switch and out to the harness when the switch is on. I asked you to check voltage into and out of the ignition switch so we would know if it is getting that far before dropping. If voltage is dropping on the supply into the switch, then we know the drop has to be in the fuseblock. If it drops immediately after the switch, we know it is the switch. If voltage is good from the fuseblock, through the switch and through the connector, we know its a harness problem between the ignition switch 6 pin connector and coil connection.

Check the input and output voltage on the ignition switch. That will tell you where to look next for the cause.

Earl

Ok, between the neg battery terminal and the o/w wire, I get a few millivolts if that!! The positive battery terminal between the o/w wire shows 11.8 volts, with the battery itself showing 12.7. Is there a grounding problem? Is this backwards? I did the test at least 10 times.

 

[Jethro]

Ignition on, red meter probe on the orange/white and black meter probe on ground or the neg battery terminal will read voltage on that wire.

That voltage is 8 millivolts. Before when I said 8 volts, it was actually 8 mv (I have an auto-ranging meter and missed the mv). I get 11.6 volts with the positive battery terminal.

I have about 11.5 volts at the ignition switch wires. I also have 11.5 volts on the orange/white wire directly out of the ignitor box. The fuse panel shows 12.7 volts on either side.

 

[earlfor]

OK then, I'll assume you have the headlight either off or disconnected, the coils disconnected and the tailight bulb removed. That should only leave the dash lights and ignitor box consuming power. I dont know the exact consumption of those two things, but it should be slight. 11.5 to 12.7 is a 1.2v drop. Would you clarify? You have 11.5v at the ignition switch wires...you said. Is that 11.5v on the input side or the output side? (the input side will always be hot regardless of the switch position, the output side will go on and off with turning the key)

Earl

I have about 11.5 volts at the ignition switch wires. I also have 11.5 volts on the orange/white wire directly out of the ignitor box. The fuse panel shows 12.7 volts on either side.

 

[Jethro]

OK then, I'll assume you have the headlight either off or disconnected, the coils disconnected and the tailight bulb removed.

Correct. The headlight is off the bike, and the tail bulbs are out.

11.5 to 12.7 is a 1.2v drop. Would you clarify?

Correct. I see a 1.2v drop between the headlight and tail. At the coils I am concerened I am doing something wrong, but it's very simple- ignition on, bar sitch on "run" red meter wire to disconnected o/w wire on coils, black meter wire on negative battery terminal reads 8 millivolts. Put that black meter wire on the positive battery terminal and I get about 11.5 volts.

Anyway, I checked before and after the bar switch wires (I think they are orange with green stripe?) and get 11.5 volts both before and after (after when the switch is on "run"). I haven't figured out where the harness to the keyed ignition is yet to test that. Any idea what color wires I am looking for for that?

 

[BadBillyB]

Just checked for voltage drop on the O/W coil wires on my 78 GS1000 and I found I was losing 2.5 volts, key on/engine off.....After following this ignition circuit all the way from the battery to the coils I found many drops along the way.....some of it was in the wires themselves, some across the fuses, some in the ignition switch (.85) and some in the emergency stop switch (.4).... After some thorough cleaning I ended up with 1.6 volt drop to the O/W coil wire. I would like to see it under a volt......Jethro if you have an emergency stop switch, check your voltage there. Thats the last switch/connector that the coil power goes through on mine......BadBillyB

 

[Jethro]

Jethro if you have an emergency stop switch, check your voltage there. Thats the last switch/connector that the coil power goes through on mine......BadBillyB

You mean the bar switch? I checked, I lose about 1.2 volts there, both before the switch and after the switch.

Tonight I checked my coil voltage again, this time CORRRECTLY. I had disconnected the wires to the bar switch and that is why my readings showed 8 millivolts. #-o I have 11.3 volts at the coils. I checked the voltage while the bike was running and at idle- about 13.6 volts.

I don't seem to be losing a huge amount of voltage anywhere, but I still have the slight stutter on take off (only after I sit and idle a minute). Still, I went for a nice 45 minute ride today- man I love those stock pipes. The quieter the better.

I'm gonna go downstairs and smoke one up and change out the pilot jets to my #40's. I also have a whole other set of carbs in the carb dip to swap out with the ones on the bike now. What the hell else does a loser like me have to do on a Friday night! :-D