Carbon fouling problem

[Jethro]

So I have my bike set up completely back to stock, in anticipation of some sweet pipes coming my way soon. I used a mock up pair in less than perfect shape just to make sure I can get the bike running right.

The sound of dual pipes is awesome. I've owned an 1100 of some sort for about 13 years now with 4-1 pipes, pods. It's nice to have quiet power, makes it feel more powerfull, like, "how does it go this fast with no sound?" And boy is it nice to have a centerstand again!

Anyway, I have cleaned the carbs, set the float height, installed non-drilled slides, all the stock jetting, screws 2 turns out, new old stock paper air filter- 100% back to stock. I synched the carbs real good, tried to get the highest idle with the screws, and went for a ride.

A 1/4 throttle chop plug read said plugs are burning good, and it pulls so hard to redline I know the mains are burning well, but at idle I am getting nasty carbon fouling. The exhaust doesn't smell rich or smoke at all, and I did a valve adjustment less than 700 miles ago (probably still check it before summer), and the electrical system checks out well.

Any suggestions? I still have gas with stabilizer in the tank, but that wouldn't be this extreme would it? Never had a problem with the Stabil like that before.

The symtoms are:
cold startup is as usual. 3/4 choke to start, in 30 secs. 1/4 choke. After a minute or two I can back the choke off. Idles well at first, about 1300 rpms.

When still warming up the throttle is responsive, but in about 3-5 minutes the idle will suffer, and take off stumbles a little more.

After fully warmed up the bike will very slowly stutter to a stall (like 2 minutes) and throttle response becomes worse. The plugs are then caked with soot.

I guess I am planning on adjusting the float height a little less rich, and changing the gas out. I'll get new plugs again too. Any thing I am missing?

[Dink]

Sounds like you have it under control, may want to go a size smaller on the pilots though.
Dink

[Jethro]

Even though the book says 45, think I should try my 40's? I don't think I have a 42.5. Is it common for the 1100's to need a smaller pilot with stock pipes and all?

[DimitriT]

Try adjusting the mixture on the idle. Turn in clockwise 1/4 turn and adjust the idle throttle knob to compensate. I like to set the screws at the fewest turns out at which I get the highest RPM. Once I have them all at this setting, I will turn all four 1/4 turn in and run with it for a while. If I get a steady idle I will turn them in a little more. I look for the leanest setting where the idle is steady at 1-1.1k RPM after running on part choke for 2 or 3 minutes. If I go too far, the idle will take too long to get steady and I will back them out a little and turn the idle throttle knob in to enrich the mixture.

[earlfor]

Sounds to me like an electricl problem Jethro. when the bike is at idle, the charging system isnt maintaining voltage and youre consuming more than is being produced. Spark gets weak and the burn is sooty. I would put a multimeter on the orange/white wires to measure voltage with the bike at idle for a few minutes. I will bet that when it sputters down and starts to have problems, you will see a reduction in voltage compared to what you started with.

Earl

[kalessin]

Are those original Suzuki or aftermarket pipes on the bike now?

I like the way they look...

[Jethro]

Original Suzuki pipes in the picture above. The only thing missing from them is the heat shields.

Sounds to me like an electricl problem Jethro.

That's something I was thinking as well. Could this condition get worse as the bike gets warmer? Becasue it definitely does. I'll play around with the meter tomorrow and see what I come up with.

[Jethro]

Try adjusting the mixture on the idle. Turn in clockwise 1/4 turn and adjust the idle throttle knob to compensate. I like to set the screws at the fewest turns out at which I get the highest RPM. Once I have them all at this setting, I will turn all four 1/4 turn in and run with it for a while. If I get a steady idle I will turn them in a little more. I look for the leanest setting where the idle is steady at 1-1.1k RPM after running on part choke for 2 or 3 minutes. If I go too far, the idle will take too long to get steady and I will back them out a little and turn the idle throttle knob in to enrich the mixture.

I spent a good hour or so messing with the mix screws. I'm convinced the only effect they have on anything is when they are bottomed completely out. My problem is that I seem to get a nice idle, the bike is running super smooth, then in about 2 minutes of idleing it ever so slowly begins to slow down and stall.

[earlfor]

I dont know if getting warmer would make a difference. I'm inclined to think
the extended running at a low rpm that does not allow to battery to charge is the real cause. My mind just keeps screaming low voltage problem at the coils. Little voice in the back of my head kind of thing. :-)

E.

Original Suzuki pipes in the picture above. The only thing missing from them is the heat shields.



That's something I was thinking as well. Could this condition get worse as the bike gets warmer? Becasue it definitely does. I'll play around with the meter tomorrow and see what I come up with.

[Jethro]

I went out this morning and checked the voltage, and at 5000 rpms, only get 13.75 volts. Battery is healthy and charged. A little more investigation revealed the reg/rec connector had metled at the red wire. It looks like that red wire going back to the harness has fried pretty good and is very brittle, but the red wire on the other side of the connector going to the reg/rec itself isn't brittle or burned. The connector wasn't so melted that I couldn't pull it apart.

I was gonna try another reg/rec I have, but I guess I need to replace that red wire. Does it go straight to the stator? Does this indicate anything specific, like I definitely need a new stator, or it's definitely the reg/rec? Or could it simply mean there is a short or bad connection and it could be anywhere?

Funny, my starter switch melted a connector late last year so bad it was dripping plastic. Guess I should have addressed this issue then, definitley a linked issue.

Any other suggestions Earl? Think this could be the cause of my carbon fouling? I do, if the fuel was too rich, I'd be able to smell it. And it would be bad right from the start. This spark issue gets worse as the bike gets warmer, like the reg/rec or another connection is getting hot after a few minutes and screwing up voltage.

[earlfor]

On your R/R and harness: I would peel back the harness casing and replace the section of red wire that is brittle. On my 450, that red wire also is the main power supply to the ignition switch, but it is not the ignition supply wire on any other bike I have had. On my 83 1100, I snipped the red wire coming from the harness and capped it off. I then ran the red wire from the R/R directly to battery positive. Everything works normally. You might want to do that instead of repairing/replacing the harness red wire.


The red wire is 12v DC positive. The stator is AC. Whatever you do, DO NOT connect that red wire to the stator! Instant Hiroshima!!! :-)

13.75 volts at the battery at 5k rpm with the headlight on high beam is healthy. Leave it alone. :-) Voltage will be higher if the battery is depleted, but if the battery is charged, 13.75 is, if anything, a bit high.

The only way to check the stator output is to disconnect the stator from the R/R and run the bike at 5K, checking each of the three phases for AC voltage.
You should get 80 volts AC on each pair of wires, i.e, 1,2 and 1,3, and 2,3.
Set multimeter to the ACV 200 scale for the check.

I think youre right. a bad connector/connection is getting hot and the hotter it gets the less it flows. I still think electrical supply problem. Only way to know is check voltages at various points and compare them to voltage at the battery.

Earl

I went out this morning and checked the voltage, and at 5000 rpms, only get 13.75 volts. Battery is healthy and charged. A little more investigation revealed the reg/rec connector had metled at the red wire. It looks like that red wire going back to the harness has fried pretty good and is very brittle, but the red wire on the other side of the connector going to the reg/rec itself isn't brittle or burned. The connector wasn't so melted that I couldn't pull it apart.

I was gonna try another reg/rec I have, but I guess I need to replace that red wire. Does it go straight to the stator? Does this indicate anything specific, like I definitely need a new stator, or it's definitely the reg/rec? Or could it simply mean there is a short or bad connection and it could be anywhere?

Funny, my starter switch melted a connector late last year so bad it was dripping plastic. Guess I should have addressed this issue then, definitley a linked issue.

Any other suggestions Earl? Think this could be the cause of my carbon fouling? I do, if the fuel was too rich, I'd be able to smell it. And it would be bad right from the start. This spark issue gets worse as the bike gets warmer, like the reg/rec or another connection is getting hot after a few minutes and screwing up voltage.

[Jethro]

Every wire between the stator and the reg/rec was pretty toasted at that connector. The yellow and red wires especially. I pulled the burnt wire and refit them, the bike runs smooth as silk now at idle! No more stumbling at take off. Voltage at the battery at 5k rpms is a solid 14.25. I'm still worried what casued the problem, and pulling that harness apart with every wire burnt make me wonder what else is robbing me of my spark... or is going to in the near future...

[earlfor]

I assume you've replaced the burned sections of stator (yellow) to R/R wire on all three stator leads. Yellow is AC input to the RR. Red is DC output from the RR to battery. I will guess that you need to check/clean the ground wire from your battery negative to the transmission case. Usually, if part of the RR toasts, it will only cause one leg of the stator wiring to overheat. If all three of your stator legs show overheating,plus the red DC output wire, in addition to faulty connector/s, I would suspect something common to all three legs. The only thing I can think of (relative to the charging circuit) that could be at fault is the main ground from battery to engine.

I (for peace of mind) would remove the headlight and check voltage available at the headlight 3 way plug. Without the light plugged in, voltage should be pretty close to battery voltage. (yeah, I know youre going to show a loss for ignition circuit being switched on) :-) If voltage level to the headlight plug is OK, I would say youre outta the forest. :-)

I will assume you repaired all the burnt wires you found.

Earl

Every wire between the stator and the reg/rec was pretty toasted at that connector. The yellow and red wires especially. I pulled the burnt wire and refit them, the bike runs smooth as silk now at idle! No more stumbling at take off. Voltage at the battery at 5k rpms is a solid 14.25. I'm still worried what casued the problem, and pulling that harness apart with every wire burnt make me wonder what else is robbing me of my spark... or is going to in the near future...

[Jethro]

I will guess that you need to check/clean the ground wire from your battery negative to the transmission case.

This should be fine, I had it off late last year and it was clean. I also added another ground off the neg terminal to the body of the reg/rec.

I'll check the voltage at the headlight tonight. Bike running or not? Or should I compare voltage both running and not?

I will assume you repaired all the burnt wires you found.

Basically I removed the connector for the reg/rec, and about 2 inches of wire from either side of the connector. Most of those wires were super brittle, and the connectors were oxidized badly. I didn't pull the entire harness apart, but I'm thinking it may not be a bad idea. The headlight voltage test will help me determine that.

[earlfor]

I dont think it will make any difference in comparative accuracy. Its probably easier to check without the bike running.

Earl

[QUOTE=Jethro]
I'll check the voltage at the headlight tonight. Bike running or not? Or should I compare voltage both running and not?