Low voltage running on 3 cylinders

[Relic]

Hey everyone, I searched some threads here couldn't find anything on this topic. Vmax 1200 1988. I rebuilt the carbs with the K&L parts you guys suggested. I synced the carbs and it ran like a rocket ship. Yay! Put it up for a month. Then I started on a new different project bike. Next time I started the vmax it cranked a bit slowly and was popping and backfiring badly out of 1 or more cylinders. Took it for a 10 mile ride . Misfiring got a little better but not much. Checked the voltage while running 12.2 after the ride.
I've got work to do on the charging system evidently. Charged the battery until full and went for another ride. Ran like a rocket ship again. So low voltage obviously was causing missing cylinders while running. Just thought I'd let you all know.

 

[Fire-medic]

Max Midnight will soon post his charging system directions for troubleshooting.

I always start with ensuring grounds are clean and tight. Then check connections from the stator to the Regulator/rectifier, and the R/R to the battery and wire harness.

If you use a lead/acid battery, make sure it's filled with distilled water.

 

[Relic]

Hey thanks FM. I'll go thru it step by step when I see his instruction sheet. Do the stator or pickup go bad frequently? 35k miles.

 

[Fire-medic]

In 30 years of VMax ownership, I've had the pickup coil go bad twice. Stators failure are not common, but they do happen. It's not like a Suzuki GS1000 air-cooled.

Here's a start:
https://www.vmaxforum.net/threads/how-to-fix-your-vmaxs-low-voltage-or-charging-problems.19108/
Look up the 'crimp fix' using the search function. You solder together wires above the battery after exposing a brass crimp which is supposed to act as a splice among the bundled wires. The benefit is better voltage to the battery.

 

[MaxMidnight]

As requested

 

[Relic]

In 30 years of VMax ownership, I've had the pickup coil go bad twice. Stators failure are not common, but they do happen. It's not like a Suzuki GS1000 air-cooled.

Here's a start:
https://www.vmaxforum.net/threads/how-to-fix-your-vmaxs-low-voltage-or-charging-problems.19108/
Look up the 'crimp fix' using the search function. You solder together wires above the battery after exposing a brass crimp which is supposed to act as a splice among the bundled wires. The benefit is better voltage to the battery.


View attachment 91202

Yep I have already redone the crimp fix which was already done by by the previous owner. I'll run through all the other procedures in this info as well.
I don't know that I have ever seen or identified on any vehicle in 50 years of owning and maintaining stuff, low system or low battery voltage causing misfiring like that.
Thanks for the help !

 

[Relic]

As requested

Hey thank you MM for a prompt response! I'll look through and follow the documents to hopefully get the output voltage where it needs to be.

 

[MaxMidnight]

Yep I have already redone the crimp fix which was already done by by the previous owner. I'll run through all the other procedures in this info as well.
I don't know that I have ever seen or identified on any vehicle in 50 years of owning and maintaining stuff, low system or low battery voltage causing misfiring like that.
Thanks for the help !

I seem to recall reading in the dim and distant past that the ICU cries enough at around 9v. Don't quote me as I've nothing to back that up.

 

[Fire-medic]

I seem to recall reading in the dim and distant past that the ICU cries enough at around 9v. Don't quote me as I've nothing to back that up.

That's true for the Li-ion batteries. Their circuitry prevents charging once the battery gets to that point.

 

[Relic]

I seem to recall reading in the dim and distant past that the ICU cries enough at around 9v. Don't quote me as I've nothing to back that up.

 

[Relic]

Yes, If you have any cylinders misfiring it may be the first and easiest thing to check. The bike cranked rather slowly but started right up, but wouldn't run properly at all. Until I charged the battery.