How to: Fix your Vmax's low voltage or charging problems

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Hi, just in case anybody else is as clueless with electrics as I am, just a precautionary note, (and please correct me if I've got this ass backwards) I followed this to the letter, and when testing the stator, I believe I've misdiagnosed it as failed because I didn't realize that by:
following step 3.1 and eliminating the connector.
I've now a ground connection through the R/R .
Am I right in assuming the stator test should be performed either before losing the connector, or with the crimped connection BUT with the R/R NOT in contact with the frame or other ground?
Apologies if this is obvious to everyone else.
Thanks Adrian.
Testing is done AFTER disconnecting the three-pin connector.
Lots of folks eliminate this trouble-prone connector altogether (they tend to melt, and eventually fail completely), but by doing that, future testing of the stator is much more difficult.
Better to replace the connector with three individual butt connectors - soldered, heat-shrinked, and assembled with di-electric grease.
Let us know your test results.
Cheers!
 
Well I have a new stator now, I may never know if the old one was failing owing to my earlier misdiagnosis, the new stator alone, made little difference, so process of elimination led me to the R/R old style, bike is an 88.
After replacing that with a new MOSFET style one I had voltage in the mid 13s, and once the connections were made directly to the battery posts, I now have 14.1 at idle and 14.2 at 2500rpm.
Phew!
I bloody hate electrics, me.
Thanks for the help, back to riding!!
 
Agreed, Great news threebeards.
Using a more modern R/R on the older model Vmaxes (when they eventually fail) is a must IMO.
 
If you haven't deleted the 3 wire connector from the stator to the R/R unit and hard wired them together, it would be a good idea to consider doing it. A corroded connector in the plug will get hot and eventually cause problems by melting the connector..
 
I haven't yet discarded the three prong connector, but I understand it's a weak link, what's everyone's opinion on upgrading that connector to a more robust version, I like the idea of keeping it disconnectable for any future testing needs.
 
I highly recommend and used PosiLock connectors. Simple to use, making a connection comparable to soldering, as far as resistance goes. Easily disconnected, and with a piece of shrink tube over them, waterproof. They do make waterproof ones, I think. Available online, Amazon or EBay.. I did all my connections for the MOSFET R/R upgrade, along with all connections for the Eastern Beaver headlight relay upgrade..They are reusable, too..
 
They sell that assorted size kit both places for about ten bucks. You get 3 pieces each of 3 sizes. One size is perfect size for stator wires, and there are enough left over to hook up a set of headlight relays.
 
This is one topic that comes up again, and again, and again, I'm pretty sure it's even surpassed the "which oil is best" threads in post count. Every time it comes up, there's lots of good info, until it slips back a few pages and the question gets asked again by another new member. There's a generic fault flowchart posted in the electrical, but I don't think it's terribly helpful especially for people who aren't really familiar with electrical systems. It's also not Vmax specific. So here I'm going to try and make a "one stop shop" to answer the common questions. Hopefully a mod will find this sticky-worthy.

-My Vmax cranks slowly or won't start when hot
- My Vmax is difficult to start, or won't start at all due to it cranking too slowly
- I have to bump start the bike if it's hot
-My headlight seems dim at idle
-I need to manually charge the battery every few rides

Step 1: Determine your voltage across the battery.
Remove your seat, grab your multimeter, set it to DC 20, and put the probes directly on the + and - posts of your battery. Don't start the bike or turn the key on. If you have a fully charged battery, you should see right around 12.6v. Here, I have 12.58, and the bike hasn't been run in a couple days.

If you have....

12.5v or better...........off to a good start
12.2-12.4...................barely breaking even
< 12.2.........................battery is not charging or generally running negative(using more power than generating)

**NOTE: Your bike will not look exactly like my pictures, I converted to COP ignition and the former rear coil mount plate now holds the replacement rectifier.
0728111903.jpg



Step 2: Check voltage with the bike running.
Start the bike up and get it to idle at ~1000rpm. If it's cold, fiddle with the choke, or if it's warm, it should be there anyway. Put the probes across the battery again and note the reading.

If you have.....

13v or better..........you're looking good
12.6-12.9............charging, but barely
12.5 or less..........something needs work

Now either have a helper hold the throttle, or use the choke to get it to fast idle at around 2500rpm. Check the voltage again.

If you have....
14-14.4v..........perfection. Stop reading and don't worry about it.
13.5- 14v........ Good, you're charging, but there's room for improvement
13-13.5v..........Marginal
>13v..........you've got work to do.

Step 3: Fix your problem.

3.1: Eliminate the connector between the three black stator wires and the regulator/rectifier(r/r). The R/R is located behind the left side passenger peg. That's right, just cut the wires on either side and toss it. Strip the ends and use the blue butt connectors to rejoin them. Don't worry if you mess up the wire ends, it's AC so it doesn't matter one bit if you reconnect them in a different order. For the time being, I would not seal the connectors. (See step 4.2). However, do make sure the connectors cannot touch each other, causing a short that can rapidly damage the stator.

3.2: Find your R/R. If you have an older bike, there will be 4 wires....3 from the stator and one + output (grounded through it's mount). If you have a newer model, there will be five (grounded through a wire).
Older model: Remove the R/R and clean around the base to ensure a good connection. Grab the red + output wire and cut it, leaving enough slack to re-splice it but as close to the R/R as you feel comfortable. Find the connector between the R/R and the harness, and remove the now useless end. Tape or otherwise cover the harness end connector. Strip the end, and get a wire gauge slightly larger than what's there (I used 14awg). Use another end connector, and run the wire directly to the + post of the battery. Put a ring connector on the end and bolt it directly to the post.
Newer model: Same as above, but do the same procedure for both the + output and - ground wires. Cut them out of the harness and wire them directly to the battery.

Doing this bypasses the notorious "crimp" in the harness entirely.

3.3 Check grounds and high amp connections.

The main ground is on the motor, right next to the oil fill cap. Remove the bolt and clean the mating surfaces to ensure a good connection. Check the connection to the starter, the starter relay (round puck under the seat, connected to the + battery post), and the battery terminals themselves. Ensure everything is clean and tight. Clean up any corrosion with a small wire brush. A dab of dielectric grease will help keep corrosion at bay but isn't strictly necessary.


Step 4: I did all that, and I still have unsatisfactory voltage at the battery or problems hot starting. What next?

4.1 How old is your battery? For conventional lead-acids, 5 years is a good figure. If it's older than that, or you don't know how old it is, it's worthwhile to have it load tested. Autozone, advance, and most other parts houses will do this for free if you ask them. Your battery may have OK voltage with no load, but if it drops more than it should under load, it could be sulfated internally or damaged. If you choose to replace it, the Odyssey PC680 is a popular alternative. Odyssey batteries are famously reliable and long lasting, and that one fits in the stock location with no modification needed. They're not cheap (if you shop around you can get one for around $120), but it's likely to be the last battery you buy. The one in my bike is going on 5 years old and still load tests like new, you can see the "red top" in the picture.

4.2. My battery is new, or I tested it and it's fine. What else?
Now it's time to get a bit more technical. Time to bench-test your stator. For this, you need a multimeter with 1-ohm sensitivity(harbor freight sells one for <$5), and the three stator wires. Set the multimeter to it's lowest ohm sensitivity scale, usually 200 or 100 or less if it's a more expensive one. Put the probes between any two of the wires and note the reading. You're looking for around .8 ohms, +/- 20%. I'd say anything from .5 to 1.1 ohms is "acceptable". If you have significantly more ohms (say 2 or more), or zero ohms, you have a winding problem. Test all three combinations of the wires (so wire 1/2, 2/3, and 1/3). All should have a reading very nearly if not the same. If one is wildly different, you've got a burnt or shorted winding.

All good? Next test. Put one probe on a good ground, then touch the other to each of the three wires. There should be no circuit (infinite ohms, usually shown as a 1------, dash, or blank screen) on all three wires. If there's any continuity, the stator is shorted and needs to be replaced.

Final test. Start the bike up and let it idle. Set the meter to AC volts. Repeat the same three wire combos. I get right around 20VAC from each leg. As you rev the motor up, it should steadily rise. If one leg is much greater/less than the others, you likely have a problem.

4.3. My stator checked out OK. What's left?

Your regulator/rectifier. If you have a pre-98 (IIRC, correct me if I'm wrong) bike, you have a shunt type R/R. You can tell because it's a smooth black box with no fins. If your box is finned, you have a newer MOSFET r/r. Shunt r/r's in general suck and they all seem to go bad eventually. If your multimeter has a diode test mode there's a way to check it, but honestly if you have a shunt, just save yourself the trouble later and replace it now. MOSFETs are more efficient and much more reliable. You can retrofit a new mosfet onto an older bike with no problem. Sean Morley and CaptainKyle both sell stock fitting replacements. If you happen to be running COPs, the rear coil mounting plate makes an excellent location for an even better R/R. Get one from a Ninja ZX10/ZX14, I found one on ebay for $20. Similar to the "R1 mod", but this one is much slimmer and will fit under the seat. In the picture the three black wires are from the stator. The red wire goes directly to the + battery, and the black directly to the - battery. Shindinguen (sp?) makes pretty much all the R/Rs for every motorcycle on the planet. If the part number starts with "SH", it's a shunt style. "FH" means mosfet. This one is stamped "FH010BA" They're usually designed to plug directly into a bike's harness, but inside the gray (stator) and black(output) connectors are regular spade terminals you can slip individual connectors onto.

0728111903a.jpg


4.4 I have a MOSFET regulator, and everything else checked out. What else could possibly be wrong?

Your stator could be shorting under load. I know, because my stator bench tested OK but I still was having poor voltage, even after I fitted the ZX14 regulator. Namely, I had great voltage when I started the bike, but once the motor warmed up it fell back down to like 12.2 at idle. Unfortunately, this is difficult to test. Rick's Electrics sells a replacement stator for far cheaper than one from Yamaha, and since it's the same part for the Vmax and Venture, you get the Venture output level. I got it off ebay for $150 shipped.


In my case I did all the initial steps, cutting out the lossy bits of the wiring harness. That helped a bit, but I still didn't have good voltage and sometimes the bike would crank slowly when hot. Then I replaced the R/R with the Ninja part. I was excited when I got 14.4v when I first started it, but I noticed the headlight was dim a bit later and it was back down to the 12.2, same as before. Finally I replaced the stator (which looked and tested fine), and now I have excellent voltage. 13.2 at idle, and 14.4 from 1500rpm on up.

-NOTE: The philips screws that hold the R/R on tend to be extremely tight from corrosion and age and are very easy to strip out. I'd highly recommend using a hammer-impact screwdriver with a #3 or #4 bit, whichever fits best.

-To change the stator, you need to drain the oil(or find some way to securely tip the bike on it's right side). Remove the left side peg and shifter clamp. You need to remove the middle gear (smaller square-ish) cover before the stator cover can be removed, they overlap. All the cover bolts are 5mm hex. The bolt with the copper washer goes in the bottom center of the middle gear cover. Once the stator cover bolts are all removed, gently pry/work at it to break the old gasket. Once the gasket breaks, you have to fight the magnets in the flywheel to finally pull it off. Lay it down and look inside. There are three large philips screws holding the stator in, and another three philips toward the edge that hold wire guide plates. IIRC you only have to remove two of these guide screws, the last is for the pickup coil. Remove the guides to free the wires. Now, use a well fitting screwdriver or an impact driver to remove the stator bolts. Again, they tend to be very tight. I got mine free with a regular screwdriver, but they were really in there. Chuck the old stator, drop the new one in it's place. Assembly is reverse of removal. It's not a bad idea to put a dab of RTV or Yamabond 4 around the rubber grommet that passes the wires through the case. Make sure to thoroughly clean the old gasket material off the surfaces(this is the biggest hassle of the job). A scotch brite pad (or suitable wheel for a rotary tool) makes this easier. Use a new gasket on the stator cover. Personally I like to smear Yamabond on both sides of the gasket for extra insurance against leaks. You need a gasket for the stator (otherwise the starter gears may bind, the tolerances are that tight). For the middle gear cover it's not necessary, mine sealed fine using just Yamabond (just because I had mine apart and the dealer didn't have any gaskets for it and I didn't feel like waiting).


Hopefully this will help out the (everyone) who seems to be having charging problems.

VMFer suggestions/tips:
-Which connector to use in splices? You have a couple options.
1. Uninsulated barrel splices (a blue butt connector without the plastic). This allows you to solder the connection for extra strength. Seal it with heat shrink rubing or liquid electrical tape.
2. Heat shrink butt connectors. Like the generic blue butt connector, except these tend to have a clear-ish plastic that's flared out a ways and they cost more. Personally I like these since it's very neat and tidy.
3. Plain blue butt connectors. My tip for crimping is to skip the cheap electrical multi-tool and buy a dedicated crimping tool, they're not terribly expensive ($20 or so) and will give you much more reliable connections. Failing that, use a big pair of channellocks and give it a good squeeze.

-Add a 30A inline fuse between the R/R and the battery to protect against overcharging. The bike's harness is still behind the 30A "main fuse", but an extra security to be sure.

-Add another wire from the - battery to ground.

-If you have an older 4 wire R/R, sand the back of the box and the mating surface on the frame. Clean off the dust, then apply a thin smear of dielectric grease to promote a good connection and keep corrosion at bay.

R/Rs are crawling all over ebay though. The "new" OEM ones will fit in the stock location even if your bike has an "old" one. The Ninja part I used was too big to fit there and went under the seat instead. Some people have ditched the tool kit and put it under the passenger seat. Let me emphasize that any modern R/R will work. They all do the same thing. 3 phase AC in, regulated DC out. Doesn't matter if it came off a jetski, snowmobile, bike, or a Honda, Yamaha, Harley, Kawi, or from a sportbike or cruiser. Shop around ebay and get the best deal you find. Like I said, one company makes virtually all of them for the powersports world.
I know this is an old post, and I have reviewed it several times. Thanks for posting. I have a 2003 VMAX and I suspected a charging problem from the day I bought it 3 years ago. After every ride I would plug it into the battery tender, and it would always take a couple of hrs to go back to green. It always started for me so I always left well enough alone. This weekend I decided to check the voltage at 1000 rpm and again at 2500 rpm. The result was the same. 12.9 to 13 volts no matter what the rpm. I followed you steps with a couple of changes. I located the stator wire plug and as you stated, used blue barrels with no plastic, soldered, and used heat shrink? This left the positive red, and the negative black to deal with. I spliced 14 gauge wire in below the plugs, again using bare barrels (yellow this time), solder and heat shrink. I reconnected the plugs and ran the pos and neg wires up and under the seat tie wrapping along the way. I attached the negative directly to the neg battery post, and I took the positive, and spliced it into the 14 gauge red wire coming off of the main breaker. My thought was keep that breaker in the circuit and eliminate adding an additional one. Back together, I started the bike and tested the voltage again. At 1000 rpm I was looking at 13.5, and at 2500 I was showing 14.2. I was more than thrilled. I took the bike out for a short 30 mile ride, and within 5 min of plugging in the batt tender, I was solid green and fully charged. This bike is in pristine condition, and always garaged. When removing the infamous stator plug, I found it be clean with no visible signs of corrosion. I say all this because no matter how well any bike is kept, they all have their weaknesses. Thanks to RaWarrior, that uneasy feeling I had about my charging system, has been resolved.
 
I know this is an old post, and I have reviewed it several times. Thanks for posting. I have a 2003 VMAX and I suspected a charging problem from the day I bought it 3 years ago. After every ride I would plug it into the battery tender, and it would always take a couple of hrs to go back to green. It always started for me so I always left well enough alone. This weekend I decided to check the voltage at 1000 rpm and again at 2500 rpm. The result was the same. 12.9 to 13 volts no matter what the rpm. I followed you steps with a couple of changes. I located the stator wire plug and as you stated, used blue barrels with no plastic, soldered, and used heat shrink? This left the positive red, and the negative black to deal with. I spliced 14 gauge wire in below the plugs, again using bare barrels (yellow this time), solder and heat shrink. I reconnected the plugs and ran the pos and neg wires up and under the seat tie wrapping along the way. I attached the negative directly to the neg battery post, and I took the positive, and spliced it into the 14 gauge red wire coming off of the main breaker. My thought was keep that breaker in the circuit and eliminate adding an additional one. Back together, I started the bike and tested the voltage again. At 1000 rpm I was looking at 13.5, and at 2500 I was showing 14.2. I was more than thrilled. I took the bike out for a short 30 mile ride, and within 5 min of plugging in the batt tender, I was solid green and fully charged. This bike is in pristine condition, and always garaged. When removing the infamous stator plug, I found it be clean with no visible signs of corrosion. I say all this because no matter how well any bike is kept, they all have their weaknesses. Thanks to RaWarrior, that uneasy feeling I had about my charging system, has been resolved.
Same here but put a 20amp fuse in line to the positive going to the battery.
 
great write up. Was ok before but under 14 at idle and 3000rpms. Direct wired it all with 30amp fuse on power line and have 14 plus at idle and 3000rpms cold fan not on. :)
 
Read the posts about a Series type regulator. Shindengen SH775. I have one in my 85 Max, and my 2002 Roadstar. They work great, and do not shunt excess current to ground. They shut off the stator when not needed. This makes everything run cooler, and protects the stator coils from overheating and frying.
 
Had a problem with my 89 max when hot. Fan comes on with misfire at low revs and will stall. Replaced the regulator and no problem now with good charge with lights and electric fan on- no more misfire


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Hi all. I recently replaced my r/r due to poor battery charging. I soldered the connections from the stator and soldered the "CRIMP". I was getting 13.5v at 1000 rpm and 14.8 volts at 1500rpm. I thought "great". Then I took the bike for a ride. Got the motor warmed enough till the radiator fan came on just to check it was working.Let the bike sit. After about an hour went to start the bike and it wouldn't stay running. when I did get it running I checked my voltages again. I got 13.5 at idle and 13.6 at 2500rpm. The battery was tested at advance auto and it was good. My question is should I add the extra wires from the r/r to the battery or is this a stator problem that only happens when the motor is up to temp.? Any advice appreciated. Thanks---Chuck
 
Hi all. I recently replaced my r/r due to poor battery charging. I soldered the connections from the stator and soldered the "CRIMP". I was getting 13.5v at 1000 rpm and 14.8 volts at 1500rpm. I thought "great". Then I took the bike for a ride. Got the motor warmed enough till the radiator fan came on just to check it was working.Let the bike sit. After about an hour went to start the bike and it wouldn't stay running. when I did get it running I checked my voltages again. I got 13.5 at idle and 13.6 at 2500rpm. The battery was tested at advance auto and it was good. My question is should I add the extra wires from the r/r to the battery or is this a stator problem that only happens when the motor is up to temp.? Any advice appreciated. Thanks---Chuck

You should run a separate wire from the r/r to the positive side of the battery with a 20 amp inline fuse and then run another directly to the ground side of the battery.:clapping:
 
You should run a separate wire from the r/r to the positive side of the battery with a 20 amp inline fuse and then run another directly to the ground side of the battery.:clapping:
I thought it was supposed to be a 30 amp fuse?

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I thought it was supposed to be a 30 amp fuse?

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It shows here that they use a 30amp fuse on this kit also--:eusa_dance:
Don't know where i got 20 amp-:ummm:------Oh it was a few answers up above here-man that guy should be banned.:band:
 

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