Stator Trouble Prevention - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Where does this wire go?
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  • 1 Post By Chris Allunario
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post #1 of 8 (permalink) Old 05-21-2019, 04:09 PM Thread Starter
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Stator Trouble Prevention

I'm doing another stator swap next week because surprise surprise, it failed. I am wondering what steps can be taken to preserve it for as long as possible. I plan on moving the r/r onto the frame outside the bike for better cooling and keeping the oil filled to the top of the fill line but what else can be done to prolong its life?

I've heard of switching to LEDs but my thought is that it would just increase the heat load on the r/r since the stator produces max power at all times (or so I read). Any insight would be greatly appreciated
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post #2 of 8 (permalink) Old 05-21-2019, 06:04 PM
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Bypass the three solid state relays in the JB, or eliminate the JB altogether. Headlight, Start, and Fan relays inside the junction box.

Headlight relay - Blue Wire Mod ... Can also eliminate AC voltage in the JB by cutting the stator feed to the JB headlight relay.
Start relay - Two-Wire Mod
Fan relay - Universal 12v Relay

A full fleet of LEDs could increase the heat load on the r/r. But lowering power demand to some extent will help overall.

Eliminating the JB means building your own.

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post #3 of 8 (permalink) Old 05-22-2019, 10:23 PM Thread Starter
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Is there a guide on bypassing the relays? I may just do the headlight since I know that's a big power draw and read that its relay is problematic. Would you recommend putting in a few LEDs such as just the tail light or tail light and turn signals to drop the power draw but not too the extent that the r/r craps out from heat and then causing stator failure?

My good news is that the stator and r/r arrived early so I knocked it out today and I'm getting around 13.4v near idle and 14.5v above 4k. I'm glad I will be returning from the weekend with both my bike functioning!

Last edited by Chris Allunario; 05-22-2019 at 10:26 PM.
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post #4 of 8 (permalink) Old 05-23-2019, 06:24 PM
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My stator lasted 80,000+ miles on my '02. The only thing I ever did was eliminate the bullet connectors in the three yellow wires. They were burned, so they were obviously a source of higher than normal resistance. I never did anything to the JB, but it might not be a bad idea. I do not like LEDS on bikes period. I grew up with incandescent bulbs, and that's what I will stay with. They work. And they would have the opposite effect to what you want, unless you plan to add some more electrical accessories. When I had a Goldwing, and belonged to a couple of Goldwing forums, people were loading their bikes down with every electrical accessory they could find, especially lights. The stator put out more power than the R/R could cope with. Some bikes actually caught on fire because the R/R overheated and set the wires connected to it on fire. You want to use at least most of the power the stator puts out to take the load off the R/R. If you overload the system, about the worst that can happen is a dead battery.

I am a motorcyclist, NOT a biker.

1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
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post #5 of 8 (permalink) Old 05-24-2019, 12:57 PM
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Sorry Jerry but I must respectfully disagree with you about LEDs. It is my belief that the benefits of LEDs far outweigh any negatives. Being SEEN is something that happens NOW and the sheer brightness of LEDs improves that possibility. The additional lighting options offered by companies such as CustomDynamics increase being seen even more. Any negative aspect to them can be countered by the rider/owner without much difficulty. Being seen today is more important to me than any possible stator or RR problem that might happen down the road in time.

There are differences between theory and practical reality. Moving the RR to a cooler spot makes perfect sense in theory (and when mine finally craps, I'll do that, too) yet how much actual help it provides is something for debate and darn difficult to quantify. Bottom line is that it sure cannot hurt and can only help, so go ahead and reposition it if you want.

The lower power draw experienced by switching to LEDs means that you can now add additional electrical doo-dads to take up the slack, so to speak, to make yourself safer or more comfortable. Go ahead and add those LED running lights, GPS, phone chargers or whatever without fear of "power brown outs" (as long as you chose your doo-dads smartly keeping in mind the draw of each item).

Keeping the stator cooler (and the pros and cons of that) is a subject broached in another thread about adding an external oil cooler. Good reading. Some of it borders on theory and again touches on theory vs. practicality. If you're interested in increasing stator life, its good background reading. In reality, there's not a lot that can be done.

But back to LEDs, I say go for it.

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post #6 of 8 (permalink) Old 05-24-2019, 06:14 PM
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The best thing is make sure the R/R is a modern MOSFET device.

Second best would be to fuse each AC line from the stator

'99 Vulcan "Victoria"
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post #7 of 8 (permalink) Old 05-24-2019, 11:00 PM
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Not enough of an electrician to know which mod is best, but a member here, who lived in the desert Southwest, rigged up an oil line to cool his third stator (had two that failed within a year IIRC). After that, he had no problems.

When my stator went out, the part submerged in oil looked good, but the part above the oil appeared burned.

I'm keepin' all the left over parts. I'm gonna use 'em to build another bike!
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post #8 of 8 (permalink) Old 05-25-2019, 01:12 AM
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I've always kept my VN750s mechanically and electrically stock, except for the manual cam chain tensioners on the '02, The first one, a new '93, lasted past 80,000 miles and was still running and charging fine when I sold it. The second one, also new, had a stator failure around 83,000 miles. I replaced the stator with a TPE rewound unit. Then the upper rear cam chain failed at just over 108,000 miles. The cam chain failure does not surprise me given the mileage. The VN750 has a nightmare of a cam chain system. I have also had 2 other bike fail due to broken cam chains. A chain is always going to be the weakest link in an engine, even if it only has one. I believe a cam chain should be considered a maintenance item, and the engine should be designed so it can be replaced fairly easily.

As for the stator failures, 80,000+ miles for a stator is not bad. Stators actually fail on most bikes before that. A stator failure should not be a big deal. The VN750 was not designed so it could be easily replaced. That is the big issue. Car alternators on the other hand, can last a lot longer. But they are a completely different design, one which I think should be used on motorcycles. A stator puts out full power all the time, whether it is needed or not. The R/R has to dispose of unused current. This generates heat in both the stator and R/R. IMO, the answer is to control the output of the stator based on the load placed on it. That has been the way it is done on cars forever. We have all this modern technology on new bikes, but are still using electrical technology from the early 20th century, and tire technology from the 1940s.

I am a motorcyclist, NOT a biker.

1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
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