Getting at the R/R - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 1 (permalink) Old 01-19-2006, 08:39 AM Thread Starter
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Getting at the R/R

Also See Regulator / Rectifier / Stator

It probably would be easier but it isn't necessary. You have to pull the battery, remove the J-box (easy - 1 bolt and unplug it, or just let it lay over to the side), then remove the 4 bolts near the top that hold the battery box in.

You can then lift the battery box a bit and tilt it to the right. This allows you to reach under it from the left side with a 10mm socket on a 1/4" ratchet (or a box-end wrench) and remove the two bolts that hold the R/R to the battery box.

Pull the cable and R/R out where you can work on it and remove the plug. Put everything back but the R/R. The whole procedure takes about 15 mins. The R/R plug has enough free cable to allow you to re-route it to the new R/R location without having to unwire anything. While you're at it check that battery box to see if it's corroded. If it is unbolt all the electrical stuff from it and pull it all the way out. Clean it good with a paste of baking soda and water using an old toothbrush to get all the acid and corrosion off. Rinse and dry it good then wire brush any loose paint off. Give it a couple of coats of Rustoleum Black paint. Let it dry then reinstall it, bolting everything back on in reverse order.

This is actually easy to do and doesn't require unwiring anything other than the battery. -- MokiMan
Good news.. you don't have to cut into the fender!
You can run the plug out and past the fender shroud and plug into the
relocated RR

Check in the files section
Files > Electrical and Lighting > RR & Stator for write-ups
Also check Photo Albums > Modifications > Jax for pictures

Go to and see what most of us here did
to relocate our RR's...

I am pretty much new to this bike but if you remove the bolt from the overflow tank and wiggle it out and to the side you can get you hand in there with a small socket and remove the R/R. A tight squeeze to be sure but it can be done. John
When the idea of fusing the stator first came up on the main VROC news group, I dug into the manual and found that the specs of the charging system state that the stock stator & regulator/rectifier can generate 24 Amps at 8,000 RPM's. Well, since very few of us would be willing to run our VN750 at that RPM for very long, I suggested we go with 20 Amp fuses because the stator and wire are supposed to handle 24 Amps. This should protect your stator and wire harness from over-current, but it will not protect your stator if the motor gets too hot.

So far, the only complaints I've seen are fuse holder connectors melting. That could be caused by a weak connection that would generate heat, thus melting the connector and making the connection worse. In electrical circuits, the device you're powering can pull as much current as the power supply can generate. If the power supply, which is the stator and regulator/rectifier combination in our case, is short circuited by the device it's powering, such as a shorted battery, the current will increase to meet the load requirements, thus making the wires hot, including the windings of the stator. If the wires get hot enough, the insulation will melt off the wire. When this happens to the stator, the windings short to each other and possibly the motor casing. That will cause the output voltage of the stator to decrease or drop to zero volts and all the electrical components of your bike will be powered only by what the battery can supply. Unfortunately, that doesn't last very long.

Q; I had the shop replace the R/R and Stator under extended warentee. Now I have trouble getting it started when the bike is warmed up, like at a gas station. I pulled the plugs and the front ones had a little gas on them. Any guess what the shop did wrong?
A: The shop f**ed up... Get it back and have your rectifier replaced!!! THose were the symptons I had before my rectifier died. Unfortunatly they will not be able to diagnose the problem. Just ask them to replace the rectifier and you might want to evaluate your battery...

Do you have a new westco type battery? might want to check the connections...

Q: Also, I gather from all this that using lots of electrical equipment >(driving lights, radio, air horns, etc.) is hard on the battery, NOT hard >on the stator or R/R. Correct?
A: Yeah, I'd say so, at least at first. What happens is that the system voltage drops below a level necessary to recharge the battery. I don't know how long or how many times it takes to ruin a battery this way, but it's sure not good for it. Once the battery starts going south, it's going to take the R/R with it, and probably the stator too if the R/R shorts out. This is why it's so important to know why the stator failed before slapping a new one in. If the R/R is defective, it's going to ruin the new stator like the old one. It's also why a working battery is vitally important to the well being of the electrical system. That's why everyone is so gung ho on maintenance free batteries around here. If you let a wet cell battery dry up, you're really cruisin for a bruisin.

Q: Sorry for being an electrical dummy, but at idle, why wouldn't the R/R send all of its current to the battery in an attempt to keep it charged?
A: I don't think it's a dumb question at all. First thing is to know that an auto alternator is way smarter than a stator in a motorcycle. An alternator will reduce it's output when the system voltage goes up. A stator doesn't, so we need the R/R. The R/R of a motorcycle is like, really primitive and not very elegant at all. You can think of it like a drain. When the water level (voltage) gets too high, it opens up and lets the excess water drain away. The only place it sends current is directly to ground. It causes a controlled short circuit. That's why it gets so hot. It only drains the current when the voltage is too high, not too low.

A battery that is working properly will "absorb" current and recharge. A defective battery won't absorb current (because it's internal resistance is higher than normal) as well (if at all) and therefore not charge correctly. Without the battery acting as an electrical sponge, the voltage goes high, and the R/R dumps the excess current to ground to keep the voltage within normal limits. So all the current the battery won't take, goes through the R/R causing it to get hot, stay hot and fail a whole lot sooner than it's suppose to. If it stops conducting all together (open circuit) the stator voltage goes unchecked and the system voltage follows the stator. If it fails as a short circuit, all the current produced by the stator shorts to ground causing the stator to get abnormally hot, melting and burning things along the way.
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