How to figure out if problem is R/R or Battery or something else?

[TNRabbit]

Something else to consider is a short that opens up when hot.

[Guest]

I have 13.8V at idle w/o lights etc. and 12.4 when lights on, 13.4V at 5000rpm w/o lights and 12.9 w lights. Stator resistance 0,2 all wires, and open circuit to engine case. 58V stator AC at 5000rmp. 12,7V no load at battery. The charging voltages seem a bit low. I also had the battery go flat yesterday while riding (oxford heated grips were on at 75%). What are your thoughts? RR is a SH689DA that has been fitted by one of the previous owners.

[mello dude]

I have 13.8V at idle w/o lights etc. and 12.4 when lights on, 13.4V at 5000rpm w/o lights and 12.9 w lights. Stator resistance 0,2 all wires, and open circuit to engine case. 58V stator AC at 5000rmp. 12,7V no load at battery. The charging voltages seem a bit low. I also had the battery go flat yesterday while riding (oxford heated grips were on at 75%). What are your thoughts? RR is a SH689DA that has been fitted by one of the previous owners.

Hi illegal,

You have the classic "upgraded" OEM R/R and they work ok for awhile, but eventually they fall out of spec. I have heard about too many that the volts drop at higher revs. (I have one sitting on my desk, nice paperweight.) -

-- I just fixed a buddys bike that had one and ran the battery down. - Its new R/R time.

-If you are a plug and play only guy, go www.wiremybike.com

-if you can do minor wiring and connection work, go www.roadstercycle.com

Also double check that battery, do a overnite charge and get load tested.

From your stator info, looks ok.

Oh yeah, check the stator connector too for the classic burn up.

Good luck dude,

[Mac Morgan]

Check roadstercycle.com for their mosfet rr kit. Comes with new connectors, wire and mosfet rr. If your stator is good, the new rr should cure the problem.

[Guest]

What about THIS one? Few times cheaper than the options mentioned above. It also seems to be a Shindengen FH R/R and even if the connectors are crap, I can direct solder the wires or find better connectors for almost nothing.

[Switchblade]

Like this one ?

[Guest]

It says FH002 on the R/R that is on eBay. It looks a bit different than the one on your picture. At the moment I have one that looks more like the one on your picture but it seems that it is not up for the task anymore.

[Switchblade]

10-4

[number9]

Is there some reason why you are suspecting the stator? It's usually the reg/rec that goes bad, and high-temperature failure is a well-documented mode...

Ciao,

Hi JZH, I agree that it is probably the RR, based on the info that I have read about the hot RR failures. I just wanted to get a sanity check because there are the two things that took me by surprise 1) the suddenness of the failure - literally in the blink of an eye it goes from perfect readings ~14.5V at 5k rpm to battery voltage, and 2) The lower-than-expected output from the stator when the bike is nice and warm (~13VAC).

I just want (as anyone would, really) to first replace the part that has the highest likelihood of being the one that will help me, and usually coming here first gets me the best info out there...

I think that I will order the RR today and see what happens and let y'all know!

Thanks again!

Sam

Sam, did you end up fixing your issue? It sounds the same as what I'm seeing - output drops as the bike gets hot.

[Switchblade]

Stator ?