Carbon fouling problem

[BadBillyB]

I would be tempted at this stage to put new spark plugs in the motor. Sounds like you have overcome a few issues you had and maybe the spark plugs have taken all they can handle......Once fouled or even close to fouled they can not be trusted.......BadbillyB

[Jethro]

But the bike runs as perfect as it ever has for the first 10 minutes. Zero vibration, perfect. That's what is making me think it's electrical and something is heating up or the battery isn't keeping charge. I'll pick up new plugs tomorrow anyway.

[earlfor]

With a battery, there is voltage and capacity. The charge curve for a battery is a bell curve. At higher voltage levels, the curve is gradual and capacity (ability to support a load) is stable. As voltage in the battery drops, so does capacity.
At 12.3 volts, there is little capacity left, so when a load is applied, the voltage plummets and things work intermittantly or stop working. Flashers stop working or work very slowly, lights burn yellow and ingnitions misfire and produce sooty plugs.

It almost impossible to troubleshoot an electrical system without having a stable voltage level in the battery for comparison at various points in the system. You need a new battery. I think a lot of the problem is a dead battery. Your saying what your battery voltage was has helped clear up some things in my mind that just didnt fit. The pieces are starting to go together now. :-) Get a battery, charge it to 13 v and then do the voltage check on just the orange white wires with the coils disconnected. Lemme know.

Earl

Well if that's true I guess I'll buy myself a new battery. The road test went as before. Runs like a swiss watch until about 10 minutes after I start riding, then I get a bad stumble at take off. But voltage at idle seems to be about 13.25 volts, and it idles nicely.

[Boondocks]

Why does the manual say it's a 12v system if the batter needs to be 13 volts!? I'm getting even more confused, if that is possible. I'm guessing this could be a huge reason why it's stumbling.

If you have a flooded lead-acid battery with vent caps, the BCI (Battery Council International) standard for a 100% charge should be about 12.65 V. Wait 4-8 hours for the surface charge to be removed and the battery voltage to stabilize before measuring. Your 12.3 V reading is about a 50% charge.

See State-of-charge reading based on terminal voltage.

[earlfor]

Hmmm, I make it a point to remember things that I know I will find useful.
Battery charging curves are one of them. Its a case of conflicting website information as what I have found overlaps your numbers rather than overlays them. I would think 100% charge would be the maximum voltage a battery could retain. The batteries in my bikes, retain a higher voltage than 12.65 indefinitely (close to anyway) :-). Uhhh, no this isnt some kind of word war, I really am curious and want to adjust my "background information" if necessary. :-) Or, give you the opportunity to adjust yours. eheheh

Earl

If you have a flooded lead-acid battery with vent caps, the BCI (Battery Council International) standard for a 100% charge should be about 12.65 V. Wait 4-8 hours for the surface charge to be removed and the battery voltage to stabilize before measuring. Your 12.3 V reading is about a 50% charge.

See State-of-charge reading based on terminal voltage.

[Jethro]

I just picked up a cheap battery at the bike shop will have to charge overnight and test on Thursday after work. I was told a trickle charge for 24 hrs would be the best, and to make sure it is fully charged before beginning to discharge it. Apparently these lead acid batteries have a better memory than I do.

[Boondocks]

Hmmm, I make it a point to remember things that I know I will find useful.
Battery charging curves are one of them. Its a case of conflicting website information as what I have found overlaps your numbers rather than overlays them. I would think 100% charge would be the maximum voltage a battery could retain. The batteries in my bikes, retain a higher voltage than 12.65 indefinitely (close to anyway) :-). Uhhh, no this isnt some kind of word war, I really am curious and want to adjust my "background information" if necessary. :-) Or, give you the opportunity to adjust yours. eheheh

Earl

Earl, this is my take on the subject. Battery charging curves are very useful and interesting, but they don't indicate the condition of the battery. They just show the rate and method of charge.

A 100% charge is the maximum voltage a battery can retain (excluding normal self-discharge). However, the retained charge can only be measured accurately after the surface charge is removed. The surface charge is a temporary higher charge reading after removal from the charger. It will disappear by itself in 4-8 hours or after turning on a current load like headlights long enough to remove the surface charge.

The state of battery charge can be closely determined by voltage measurement with a very accurate digital voltmeter. The voltage is affected by battery type. AGM batteries will have slightly higher voltage readings than flooded batteries (vent caps).

Rather than use my own numbers, I used the BCl international standard voltages in my first link. This is to avoid personal differences in batteries, voltmeters, etc. and use the recognized standard as the authority. As I mentioned, this is for flooded batteries (vent caps).

Earl, I know that you have an AGM battery. Because of their more efficient construction they typically read from 12.8 to 12.9 volts when fully charged. These numbers are coming from Battery Tutorial at Batterystuff.com. Although these voltages correlate with my own AGM battery, I use their numbers as an authority. By using sources with undeniable expertise in batteries, I hope to bypass conflicting opinions or a "word war".

[earlfor]

Ok, not a puzzle at all then. I dont know why the differences between flooded and AGV didnt come to mind. I thought I was awake, but apparently, I wasnt. :-)

Earl

Earl, I know that you have an AGM battery. Because of their more efficient construction they typically read from 12.8 to 12.9 volts when fully charged. These numbers are coming from Battery Tutorial at Batterystuff.com. Although these voltages correlate with my own AGM battery, I use their numbers as an authority. By using sources with undeniable expertise in batteries, I hope to bypass conflicting opinions or a "word war".

[Jethro]

The battery I just got came with instructions on charging and such, and the sheet says that a CB battery is 100% charged at 12.7 volts, 75% at 12.5, 50% at 12.2 and 0% at 11.9 or less. For standard batteries, 100% at 12.6, 75% at 12.4 and so on.

Can we get back to my problem here?! NO HI-JACKING!:-D

Just kidding. I need all the education I can get. 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?

[Jethro]

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

[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.