Voltage Regulator

[81Delorean]

I think my bike is overcharging so I'm going to do something with the voltage regulator. I see that RPM has a voltage regulator upgrade from stock and I also have read about an external Bosch regulator that can be done. My confusion (which happens when I start reading into things) is do they achieve the same result at the end? It's just a matter of  what route you want to go?

[86FJNJ]

Would adding heated grips, a phone charger, and some auxiliary lighting help the overcharging?

[Pat Conlon]

15+ volts FJ overcharging is very common. Ever wonder why our RED plugs are melting?

FJ's oem old school lead acid batteries seemed to tolerate this voltage unlike the newer batteries.
I remember charging light bulbs frequently. Always Looking for the LL long life bulbs.
On long hot rides, I've  boiled my battery dry on several occasions. Just add some distilled water, and don't forget the hose vent!
I've also burned up a perfectly good Westco AGM sealed battery. It seems as though AGM and Li batteries don't like 15+ volts charging.

I've tried twice replacing the VR using the original location (in the generator housing) but they too failed after a year or two.... I never had this problem with my I-4 Hondas (500/750)

My conclusion: The problem isn't the VR, the problem is where it's located.

FJ History: In 1984 Yamaha tried something new on the FJ. Previous I-4 engines had the generator located on the side of the engine in line with the crank, hanging off the end of the engine, but this added width to I-4 engine, something the racers never liked. To narrow the engine they would remove the generator, install a blank plate and run a total loss battery system, and for 20 laps it would work.
To reduce the width of the new FJ I-4 engine, Yamaha relocated the generator to a location behind the cylinder bank. Great!  Now the new FJ1100/1200cc I-4's had the same width as the 750's, Very Cool...
...but alas, an unfortunate side effect....not so cool for the internal VR.

Only when I went to the Transpo VR and located it away from the engine heat and vibrations did I find a permanent solution. Simple mod. Problem solved. 14.4 volts rock steady. My AGM and light bulbs love it.

https://fjowners.com/index.php?topic=661.0

Cheers

Pat 

[mike g]

problem is voltage check level comes through ignition switch and drops a bit throught the contacts, if you wire it direct to the battery via a relay (switched from the original lead) it sees actual voltage, mine now charges at 14.5v not 15 fairly easy job, might even be a link on here on how to do it

[Sparky84]

Would adding heated grips, a phone charger, and some auxiliary lighting help the overcharging?

15+ volts FJ overcharging is very common. Ever wonder why our RED plugs are melting?


Cheers

Pat 

I wouldn't think that extra voltage would be the culprit in melting the RED plug, more a bad connection resulting in a "hot" joint, with amps trying to get through but can't resulting in it heating up and losing the battle.
Keep those plugs maintained 

[81Delorean]

Thank you all, sounds like the best course would be to just mount the external regulator and be done with future issues with heat and everything hopefully. I'll get one ordered today sometime. Thanks again for all the advice on everything that gets posted on this site.