Confounding 5th Gen charging problem - SOLVED

I've been meaning to do a post on this ever since we figured it out, but am just now getting time. The good news is the bike has had plenty of time (months) and miles (including an iron butt run) to prove that it is well and truly fixed.

I'm going to try to make this as short as possible, but that's difficult for me.

This is my friend's bike and I helped him with it.

Specs: 1999 5th Gen VFR. Purchased used with 16K miles on it. Owner didn't have right battery when purchased and battery that was in it was dead. Should have been a warning. Replaced the battery with a new (correct) one that was given a full charge before installing.

Bike seemed fine for awhile but eventually just died one day while riding. Battery was found to be discharged. Charged battery - checked voltage while running, didn't see good numbers. Did tests on page 16-3 of the Honda Service manual (which is all-but-useless for this particular problem by the way):

Steps in the Honda troubleshooting diagram went like this:

1. Measure charging voltage (s/b 14.0-14.8V @ 5000rpm) = FAIL - voltage at battery low at 5000 rpm (like 12.8V)
2. Check voltage between the battery line and ground line of the R/R (3 tests) = PASS
3. Check the resistance of the charging coil at the charging coil line of the R/R connector = PASS

The diagnosis per the Honda chart for the above is "Faulty Regulator/Rectifier".

We knew that the 5th Gen VFR's were prone to bad R/R's, so this wasn't shocking, but the number on the R/R on the bike indicated someone had already replaced it with the updated R/R. Anyway, the chart said replace, so fine. Since we were ordering parts, to be proactive (in case the R/R didn't fix it) he ordered a stator as well.

Parts came in. Replaced R/R. Repeat steps above with same results. Honda chart says "replace R/R" - duh, that's what we just did. We go ahead and replace the stator just for giggles.

Repeat above steps - same result. Charging voltage still sux. He decides to charge it, ride it and see what happens. Predictably, after a few days, it's dead again.

Did some research (here, VFRDiscussion.com, etc.) and came across a post that referred to ElectroSport's Motorcycle Electrical Fault Finding Chart. I took a look at it and it did a helluvalot better job satisfying my engineering side than the Honda service manual did. You need to go grab the PDF at that link. It's a freebie.

We worked through the (very thorough) steps in the guide (you'll need a good digital volt/ohm meter if you don't already have one). Fairly fast we hit an end of the line box in the troubleshooting chart and it said:

Well, cool. That's better than before. We start digging around the electrical between the battery(+) and the RR. While a lot of it is wrapped, part of the exposed wire we found had gotten so hot it had melted into the plastic around it. Seemed like as good a place to start as any. Dug out the wiring schematic to see what the path from the battery(+) to the RR was. Unfortunately the schematic is a straight line as-the-electricity-flows sort of thing and doesn't really give an idea where the wire is routing and connecting. To make an already-too-long story a bit shorter, the bottom line is that the harness segment in the attached picture was the principal part of the problem. There is a short piece of wire that goes from the end connection on this harness to a crimp point in the main harness that connects to the R/R, but we did not dissect that wire out of the harness (we cut up a harness he bought off eBay from a wrecked bike and decided it was too invasive unless it proved absolutely necessary).

We ordered the new cable part (the one shown in the picture) and installed it. It didn't bring the battery voltage quite up to 14.0 @ 5000 rpm, but it was like 13.8 I think (which is a helluvalot better than 12.8) and we decided to run it like that for awhile and see how it went. He rode it a week and then put the battery on the garage charger to see how much it would take to top it up. The charger said "full" after 60 seconds (the minimum time it will run) so we knew the battery was staying fully charged.

Unfortunately we replaced the stator and the R/R when we didn't need to. Had we had the ElectroSport guide at the outset we might have avoided that un-necessary work and expense. Well, he's got spares now.

My theory about what happened is this (I have to have a theory):

1. When prior owner had it, the bike's R/R went bad
2. Prior owner just kept charging the battery and running the bike off the battery and re-charging the battery each day
3. Eventually the prior owner replaced the R/R but by that time this weak-link in the wire harness had been resistance/heat damaged
4. Even with the new R/R now there was a degraded path from the R/R to the battery so the battery still wasn't charging
5. Prior owner kept charging/riding/charging/riding until he sold it

Once you tear into the electrical as deep as I did you'll find that the two positive wires that come from the R/R and feed the bike are pretty decent size. The wire that comes from the battery to the starter is pretty decent size. The wire that comes from the battery(+) to the output of the R/R is pretty small. If the bike is operating correctly, the small wire from the battery(+) to the R/R is only ever used to charge the battery using the output of the R/R (which is a relatively low current operation). This single little wire is clearly not meant to provide main operating power to the bike for any significant period of time. If your stator is out or your R/R is not working, all of the electrical demands of the vehicle are supplied across this one little wire. If you do that for very long you will cook the heck out of this little wire and the copper will break down and have internal resistance. Once that happens then it won't even do a good job doing what it is meant to do, which is provide a path for the R/R to charge the battery.

See, I told you I have a hard time keeping it short!

Hope this helps somebody. My friend was at his wits end. Things like this are so frustrating they will make you sell a bike. I'm guessing (now) that's why the prior owner sold it.

 

Nice write up bro

I have been down the R/R path myself, fortunately my wiring is still in good shape.

I too noticed the relatively small battery charging wire and have to decided to keep it on a battery tender at all times when it is parked in the garage, that way minimal charging should keep everything topped up in the battery. Worked out well so far.

 

Dija know that Gen 1, 2,and 3 wires-- almost everywhere in the system--are substantially thicker than later gens??????

Seems Honda got more electrical faults after they decided to downsize wiring......imagine that??

 

I think you nailed it. I had some battery charging problems on my '99 a few years back and ended up running a substantial parallel wire from the R/R (+, red wires) to the battery (+) and haven't had any problems since. The Electrosport diagnostic is very good. Upgrade those wires! :thumbsup:

Here's the Electrosport link: http://www.electrosport.com/technical-resources/library/diagnosis/fault-finding-guide.php

 

During the troubleshooting (which I didn't post all the details of or the post would have been 10 times the size) that was one of the things we did that convinced me that replacing that harness segment would help. I soldered a large wire to the output of the R/R and connected it to the battery. That made the numbers happy which confirmed we were on the right track.

The repair you did (with the jumper wire) is actually an electrically superior repair to what we did. I wanted to try to keep everything stock (if possible). If what we did didn't work, then I was going to go with the jumper wire.

If someone wants to really do it right (instead of pretty), and wants to do the jumper wire discussed above - here's how you'd do it. The connector circled in blue in the picture below connects to a wire on the main harness that has only about an inch of wire showing outside the harness wrap. That wire goes back toward the rear of the bike and and is crimped/soldered to the two (+) wires that come out of the R/R where they merge and connect to the main (+) feed for the whole bike (we cut up a scrap harness to see how it all comes together). Soldering a decent size (I'd use 12 gauge) wire from that crimp/solder point (or any point that captures the two (+) wires that come from the R/R) to a appropriate size terminal connection to the battery would be an electrically superior repair that should last the life of the bike.

If you really really wanted to do it right, and pretty you'd unwrap the entire rear half of the harness, fish that wire out, uncrimp/de-solder it, replace it with a 12 gauge wire terminating on the appropriate connector to plug back into the factory connector in the blue circle in the picture, and re-wrap the whole thing. That's where my lazy side wins out over my anal retentive side. I'd have to be pretty bored to do that last option.

 

I believe all of these repairs (and more) are covered with the VFRness (Wire My Bike). Am I wrong on that? I recently replaced my R/R and added the VFRness and have had zero electrical issues since (and I've been carrying my multimeter around with me and testing at regular intervals).

 

It's funny, I don't own a VFR, but since my friend and wife both do, and since I'm the engineer of the bunch, I'm getting to play with them plenty and learn about them. Back when we troubleshot his bike I hadn't spent as much time here as I have now and didn't know about the VFRness. I was checking out Wire My Bike the other day (after seeing it referenced here by others) and definitely think the VFRness (and other products he's making) are a worthwhile upgrade.

My wife's bike is a 2000 (and friend's is a '99). Wires on the wife's 2000 look great, but I'm considering a VFRness as a prophylactic solution [how long before someone makes a joke about that (albeit appropriate) use of the word "prophylactic"]. Tightwad has built his harnesses the way I'd build 'em -- go heavy on the wire -- it's comparatively cheap and it can't be too big. But even better, he's already built 'em -- everything is the right length, shrink tubed, soldered (presumably), etc. No sense re-inventing the wheel. He's priced 'em right.

That said, I'm glad that I went through everything I went through on my friend's '99. I learned a couple things about motorcycle charging systems in general that are bound to come in handy some day.

 

Yep. The VFRness is the way to go. Just recently read about that. Hadn't found out about it before doing the above writeup. It would probably be possible to revise my huge post above with one that reads like this:

If you're having electrical problems, order and install VFRness. If that doesn't solve your problem, proceed to work through the ElectroSport document. :biggrin:

But hey, I wouldn't have learned anything that way. Some of us (me) just have to do things the hard way -- at least the first time.

 

electrical help

I am having trouble with my 1986 electrical system.


My battery is leaking off so I started trying to trace back from the battery and the first thing I found was that my main fuse on the wireing connector was actually melted/blown so bad I can not even get it out. I took it to the shop and they said my starter relay switch (attached to the wireing harness) was fine.

So I am now thinking that it may be my rectifier?

Any possible help?

Thanks
HVFR86