New owner w/ R/R - Stator - Alternator Questions

Hey all,l

Like the title says, I'm a new VFR owner. I have a 96 and I'm trying to diagnose a charging system problem. This is going to be pretty verbose, so brace yourself. I appreciate any help/suggestions you might have to offer.

What I'm noticing is that my battery keeps dying. The night I bought it, I had a buddy ride it home for me because I didn't know how to ride yet. It's a 45 minute ride from the seller's house to my house. After that 45 minute ride, the bike wouldn't start back up, the battery didn't have enough juice. I figured that ride home shoud've been enough to fully charge a healthy battery, so the battery must be bad.

I replaced the battery a few days later, and the bike started fine. Then I started and finished my MSF class, and spent a couple hours riding with my buddy, the bike ran great that whole day. I went riding for a couple hours a day every other day up until today, because the bike wouldn't start again. I took my portable charger and jumped the battery and the bike started right up. While it was running, I disconnected the negative terminal and the bike died immediately. This leads me to believe that the stator is faulty because the bike is running from battery power as opposed to power provided by the stator.... which would explain why my battery keeps draining.

To the best of my knowledge, and please correct me if I'm wrong, the battery is only used to start the bike, and to power the accessories if the ignition is on while the engine off. If the engine is running, the alternator/stator should be providing juice for the accessories and the spark plugs, as well as recharging the battery. So theoretically, you can remove the battery from a running engine and it will continue to run.

The part that I'm most confused about where the regulator/rectifier comes into play. I'm not very familiar with what role they play. On a basic level, I kind of understand that they convert the AC power from the alternator/stator to the DC power which is required by the bike's accessories and spark plugs. So, in theory, a bad R/R would cause the bike's electrical system to draw DC power directly from the battery instead, again causing the battery to drain.

If what I'm assuming is correct, how do I diagnose a faulty R/R vs. a faulty stator?? Any suggestions?

Thanks in advance....

 

This bike cannot run without the battery fully connected.

In my experience, it is almost always a combination of bad R/R and corroded connections. The cure is to first clean and re-connect all your charging system connections, then replace the R/R.

I keep a multimeter handy, and test the battery with the switch off, switch on, idling, and up the rev range. Normal for my bike is 12.8 or so at rest, at least 12 with the key on, and 13-14.5 at anything above idle.

Does that help at all?

--Thomas in San Diego

 

It does help, and I appreciate it.

I actually went and bought a miltimeter this morning and was out in the garage with it and my Haynes manual getting various readings. I don't think I tested anything with the engine running though. But, with the ignition turned on without the bike running, I noticed that I got good readings from the actual harness itself for voltage and resistance. I checked for resistance between different points on the R/R itself and got NOTHING when they should've actually been similar to the resistance I got from the harness... Haynes says that the R/R would be the culprit in this situation.

I was planning on waking up tomorrow morning and getting on the phone to call Electrosport to order not one but TWO new R/Rs from them so I could have a spare.... but before I do that, I'll do what you suggest and test voltages and resistances with the bike running and at operating RPMs to see what else turns up.

All of the connections actually look clean from what I can see, but I can't find the connections to the alternator??? Haynes doesn't do the best job of describing the alternator's location other than that I need to remove the left side middle fairing, and the four bolts that secure the alternator.... ?? No pics, vague description, I'm lost....

 

Well, there really IS no alternator. The charging system consists of the Stator, Regulator/Rectifier, and battery. (The stator is what you see with all the wrapped wires, when you remove the crankcase cover)

In a system with an alternator, such as a car, the alternator contains both the stator and the r/r within the body of the alternator.

I would get the updated Honda R/R, and you may need a new battery as well--running a new battery with a bad R/R will likely have ruined the battery.

I have always bought my parts from either servicehonda.com or dynamohumm, the cheapest sources for OEM parts...

 

Try to remove the battery line when the bike is running faster than 1500 RPM's. That is when the charging system kicks in and if it dies then its not chargeing. If it doesn't charge I would start looking at the wires going to and from the RR.

 

I was out in the garage just now w/ my battery charger and my multimiter.

I jump started the bike and tested the battery voltage while the bike was idling, I was getting about 11.5 volts at first (I only let it charge for a few seconds), but it was steadily falling for as long as the bike was running.

After letting the bike run for a few minutes and get warmed up, I revved the engine to 4000rpm and held it there. I was getting all kinds of readings ranging from 11.05 to 13.50 from the multimiter.... so the battery couldn't have been charging effectively. I pulled the negative battery cable and the bike ran for a second or two and stalled.

The bike wouldn't start back up, so I jump started it again, revving it to 4000 rpm and tried the same test.... disconnected the negative cable and the bike actually continued to run. It was struggling to stay running and actually backfired a couple times. I also noticed my headlights would dim and then light back up, and then I noticed my speedometer moving even though the bike wasn't... I was going to check the voltage at that point but the backfiring made me nervous so after a couple seconds I just shut the engine off. It probably would've continued to run if I had kept feathering the throttle but it sounded and acted like a completely different bike and I didn't want to screw anything up by allowing it to run like that.

I jumped it a third time and started it (letting it just run from battery power) and it started and ran smooth. I just wanted to make sure I hadn't done it any harm, but everything seemed fine.

 

I think that I had the same problem but my RR was unplugged. But you seem to have a different problem like the charging system itself or the RR or the wiring going to it. I don't think its a bad battery though. There is 3 wires going to your RR from the stator and 2 going to your battery. Test the ones going to your RR with the battery installed and it running. If its over 13 volts its charging and your RR maybe bad so test the volts coming out the other side of the RR. I could be wrong about the volts and the number of wires going in and out but I try it anyway and tell us what results you get.

 

I would strongly discourage you from running your bike with the battery disconnected. It serves no purpose, and can harm your system.

Your test sounds like a bad r/r, but you can't be sure unless you have a fully charged battery first. (Charge battery overnight on a charger before testing the R/R)

 

Your multimeter voltage readings indiate a faulty R/R. It's time to replace it. One thing I can suggest before you do this is to fully charge the battery so that with the bike off, it reads a voltave of at least 12.5. Then re-run the test. But I am betting the results will be similar. You might not see the voltage fal like you described, but it won't reach the 14.5 volts spec'd in the service manual.

 

Thanks guys for all your help. I went ahead and ordered a new R/R from Service Honda....which I just found out is only 15min from my house. I should have it on Thursday.

Anyone have any idea how long the oem replacements last? My bike has about 15,700mi and this appears to be the original R/R. Should I expect the replacement to last as long? Should I have ordered a spare?

 

I would expect the replacement to last a lot longer. The new ones are supposed to be upgraded.

One of the things that messes them up, is grungy corroded connectors, so make sure you keep that stuff clean.

The other thing that messes them up is excessive heat. The bike produces electrical power based on your RPMs, regardless of how much power you need. Any extra electrical power the bike generates, gets dumped into the R/R which turns it into heat and radiates it. If the R/R can't radiate the heat quickly enough, it overheats and breaks down. So you want to make sure the R/R is attached solidly to something metal, like the frame, because that is a supplemental heat sink. And you want to make sure you don't do anything to block airflow over the R/R's cooling fins.

 

Ditto re the connections/heat dissapation. I had 2 VFRs that went 40K and 120K miles, respectively, on the original R/R, and 2 that needed new ones every 20K or so. I suspect it had to do with the integrity of the connections, and the condition of the battery.

 

On my '96, the previous owner put some white computer CPU heatsink goo underneath the new "finned" R/R that he had to purchase last summer.

Is this a bad thing or a good thing for me? I wondered if this was such a good idea when he told me about it...

 

I got my R/R from Service Honda on Thursday, installed it and the bike has been running great ever since.

Thanks again everyone for your help.

 

Good to hear that you got it fixed. I hope that you stick around long enough to show some pictures of your bike.

 

if the battery problem occurse after all recomanded checks get a new regulator. it's offered at ebay about 70 $

 

It ended up being the R/R, which I replaced. It turns out that riding on a bad R/R DID fry my battery, so I went and bought another one. I've been riding problem free for the past few weeks and I'm loving it.

 

Just for confirmation. My brother and I finally talked about his CBR that he had a while back and he said that it had the curse of the R/R. But he called it the stator. But what he discribed replaceing was in fact the R/R. But he said that he would ride and then the battery would be toasted. And as soon as he replaced it, it worked like a dream. He sold it last year for a song. $1,700 to pay a phone bill. A 99 CBR 900 for that cheap I was I bought it.

 

OMG, if I saw a 99 CBR any size for that price in the paper I would've been knocking at the door at 6:00am w/ a cashier's check, the bill of sale all made out, and a pen in my hand for him to sign on the dotted line!