Check the AC voltage output from the stator with engine running:
Leave stator disconnected from the R/R and start the engine.
With meter set to read AC Volts check
1-2
2-3
3-1
All three should be the same value – any significant difference of one reading will indicate a bad phase and the stator is probably defective.
At idle this should be ~ 20V* and rise to ~ 70V* at 5K rpm.
I hesitate to use absolute numbers here as this can be different between models and test equipment and especially the engine rpm!
What you are looking for is same value between phases and like increase on each phase as rpm increases.
If any of the above tests raises suspicion, remover the cover & inspect the stator. It is simple to do and can set your mind at ease by seeing what it looks like.
Hopefully NOT with 1/3 of it a black charred mess!
If you have to replace the stator and R/R, especially because of a shorted R/R and excess current drain, be especially careful to ensure that your wiring has not burned. Replace any cable &/or connector plug that is not in good condition.
Now on to the alternative R/R replacement
- as aforementioned this is a good preventive upgrade measure with a better component, not necessarily limited to replacement on failure. Either way, process is the same.
Best widely available R/R on the market was the Shindengen FH012AA used on the late (06+) Yamaha FJR, 07+ Yamaha R1 among others this has now been now superseded by the better FH020AA
What makes it better is that is a MOSFET controlled device rather than the crude SCR shunt type that is on our Ducati's.
MUCH better voltage regulation and runs cooler too due to more efficient device and control circuitry.
The SCR shunt type consumes more energy in the Regulator itself than the bike is using and dumps a ton of excess current into the heat sink (feel yours & just see how hot it runs after a ride - don't touch it - you'll burn yourself - seriously!)
The problem is exacerbated because their efficiency goes even lower when they get HOT so it's a vicious circle. Heat is the number 1 killer of these devices.
Incidentally it’s a misconception that shunt type work harder with increased load i.e. higher-wattage lights, heated grips etc. - actually, the higher the load on the output, the less work the shunt regulator does in dumping that excess energy and will actually run cooler!!
The FET has extremely low resistance in conducting state and this’ results in a lower dissipated power from the device while conducting load current, as opposed to the SCR which shunts the maximum current across a significant volt drop, resulting in a higher dissipated power - and resulting temperature, much more so than the FET device.
Parts Needed for a direct swap
Shindengen FH020AA or FH012A0
Triumph link lead part number T2500676
