4Th Gen R/r Or Alternator Swap?

Riding my '94 750 last week. Stop to get gas. Had to push start it afterwards, and decided to head right home. On the way there, at a steady speed, the tach and speedo were jumping all over the dial.

Got a new battery after mine tested as irrecoverable, and it had about 7 years on it, though all of them on the Tender. The light behind the clock no longer worked, which was odd, but the clock still did. FIgured it was the bulb, and ordered another one.

Then, headed home the next night with the new battery, stopped @ a stoplight it died on me while idling. Tried the push start again, didn't work. Got it jumped started @ a gas station, made it one more mile, then it died in motion while pulling into the garage. Left it off the Battery Tender that night. Tried it next morning, and it wouldn't start, so I clipped it to the Tender again, and rode the 800 to work instead.

Today I took the multimeter to it. It started fine on the Tender, voltage @ 12.4V. RPMs up to 4k, but voltage still @ 12.4V.

So, I know it ain't charging, but here's my question: do I need a new R/R (this will be my third. OEM one: 32k. #2 was also OEM, though the re-designed finned one: 24k.) or a new alternator? How to tell?

Last time I lost a R/R was while riding. Tach and speedo were all over the place then too, but I was doing 65 on the freeway. Loss of power, but I could drop a gear now & then and limp it home, so I did. The OEM R/R had that small solid puddle of black stuff on one side, and it was easy to tell that the R/R failed: the puddle had turned to liquid and dripped all over the frame, etc.

My guess is the R/R. Sounds identical to my only failure of anything in ten years on my 4th gen. I purchased a new battery and R/R with the heat sink on one side and 30k more miles with no issues. I think the R/R ran about $120 and another $90-ish for a good battery from Batteries Plus.

Check if the plug into the R/R is indeed ALL the way in.

Before you do, unplug and inspect the wires into the plug and the little "shoes".

Press the plug ALL the way in....  

After I installed the VFRness, I omotted to push it all the way in, with the symptons you describe as a result.

Good luck!

Check the molex connector that joins the stator wires to the main wiring harness to make sure they are not burnt or corroded (located behind the right mid panel) 

The only test you can perform on the stator itself is to warm up the bike and then check the A/C voltage coming from the 3 yellow wires and check to make sure there is continuity between all the yellow wires.

Rollin

Since changing/upgrading the R/R is easy enough to do, its probably a good time to do that. I've heard that a bad R/R can damage the battery.
Anyway check all the wires going from the stator to the R/R, then to the starter relay and battery. It basically sounds like you aren't charging the battery while riding, so it could be a fried wire somewhere in that circuit. I had a starter relay melt on me and that killed the connection.

Paul in SoCal

Getting ahead of myself here a little, but if you have an R/R you're not using/gonna use (probaby should go with the OEM one, not aftermarket) drop me a line. I'm checking it out this weekend, but I may be interested.

Hey there, having charging issues here too, will save you the drama, (link to the other thread), just wanted to say I'm looking into this unit here (link to electrosport) for a 4th gen, and would appreciate opinions. I'm in Mexio which limits shipping options a bit.

Thanks

I've replaced the R/R on all my bikes with late model GSXR regulator/rectifiers with good results. I've found them on ebay for as cheap as $10, but usually around $30.

Paul in SoCal

Anything special I'd have to do to a GSXR one to make it work on my 94 VFR 750, Paul?

-greg in SoCal

check out http://www.easternbeaver.com for connectors and wiring kits to run newer mosfet style R/R's. I've bought zx10 R/R's but R1's work as well as some others... 

Nothing special. I just crimp spade or bullet connectors onto the wires. On my original 94 (245K miles) I rewired most of the wires with slightly heavier-gauge wires, and ran the ground straight to the battery negative terminal. I dremeled the stud off the subframe and drilled a hole in the subframe plate to mount the gixxer unit. Pretty minor modifications overall.
Paul in SoCal

I've gone the route of the GSXR R/r as well with good results. Want to go back and redo my wiring, but otherwise great.

Greg, where are you located? Drop me an IM if you want a hand.

Figure out of the R/R is bad or the stator, fix the issue there, then install the VFRness.  Ensure that the rest of your wire harness on the bike is good.  I had all sorts of issues with my charging, replaced the stator, R/R, still had issues, after riding the bike through knee deep water (knee deep while seated on the bike) my wire harness was completely cooked which resulted in some real-man moves to get it home (more on that some other time).  Anyway, I replaced the wire harness installed the VFRness and have never had an issue since.  Bike starts and runs like it were new.  Hope this helps. 

DD