Do I need to relocate the r/r if I go with mosfet? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 12 (permalink) Old 10-01-2017, 06:58 PM Thread Starter
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Question Do I need to relocate the r/r if I go with mosfet?

Greetings

I have a 2001 750

I've been having charging issues. I replaced an r/r last year and charging worked until recently.
-I still have the goat belly.

-2nd R/R fails testing.

-Relatively new battery.

-Stator resistance tests out correctly between each leg, voltage is good between all 3 legs when running at 3k rpm, both hot and cold and I don't seem to have any shorting when hot or cold. Tested it multiple times.

I'm going to cut out the bullet connectors on the stator and just solder/heat shrink the wires. I want to replace the R/R with a mosfet unit. Have people generally been relocating the mosfet R/R if they still have the goat belly? Is it necessary?

Thanks for any guidance.
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post #2 of 12 (permalink) Old 10-01-2017, 07:23 PM
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its always a good idea to relocate it, regardless of type.

Under left side cover is the easiest, (need to fab a simple metal bracket), or you can locate it on one of the frame rails near the left side cover, just behind it, it will be out in the 'wind' so to speak.

either location works well.

Mine is under left side cover (mosfet), and I still have the goats belly. Also, cutting out them bullet connecters is A-OK in my opinion, as they are a known problem area

2005 VN750

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post #3 of 12 (permalink) Old 10-01-2017, 07:53 PM
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The mosfet I used was larger than stock, so I put it under the left side cover.

The aluminum bracket I made, bolts up to 2 bolts on the battery box. I made a template with card paper to get the bends right and traced it to the plate. You'll want a bit of space between the r/r bracket and the Junction Box.

I used the bottom of an aluminum frying pan, easy to bend/cut, it's rigid, and sheds heat well.

MOSFET is good, gets all the charging system out of the Junction Box, eliminates stock r/r wiring.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf

Last edited by Spockster; 10-01-2017 at 07:57 PM.
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post #4 of 12 (permalink) Old 10-01-2017, 08:03 PM Thread Starter
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Quote:
Originally Posted by michiganteddybear View Post
its always a good idea to relocate it, regardless of type.

Under left side cover is the easiest, (need to fab a simple metal bracket), or you can locate it on one of the frame rails near the left side cover, just behind it, it will be out in the 'wind' so to speak.

either location works well.

Mine is under left side cover (mosfet), and I still have the goats belly. Also, cutting out them bullet connecters is A-OK in my opinion, as they are a known problem area
Thanks for the reply. I like the idea of putting it under the cover too. Any chance you have a picture of how you did it?


Quote:
Originally Posted by Spockster View Post
The mosfet I used was larger than stock, so I put it under the left side cover.

The aluminum bracket I made, bolts up to 2 bolts on the battery box. I made a template with card paper to get the bends right and traced it to the plate. You'll want a bit of space between the r/r bracket and the Junction Box.

I used the bottom of an aluminum frying pan, easy to bend/cut, it's rigid, and sheds heat well.

MOSFET is good, gets all the charging system out of the Junction Box, eliminates stock r/r wiring.
Thanks to you too. I think I like the idea of some protection from the side cover. I guess I need to figure out how to make the bracket needed. Do you happen to have a pic of yours? I'm going to get the same r/r that you got (saw your reply in another thread) Hopefully it solves the charging woes.
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post #5 of 12 (permalink) Old 10-01-2017, 10:24 PM
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Don't have a pic yet, but there's one in the link below. Same location, my bracket is a 90 bend in both bends, I left a smaller gap between the JB and r/r. But there's plenty of room to work with. Nice thing about a cardboard pattern, you can mess up 100 times and costs nothing. I did it in one try.

See post #4 by thtanner. If you can find the thread he posted on his job, he has more pics there. https://www.vn750.com/forum/70-projec...relocated.html

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #6 of 12 (permalink) Old 10-02-2017, 08:37 AM
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yup, thats just how I did mine

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post #7 of 12 (permalink) Old 10-06-2017, 09:28 AM Thread Starter
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The FH020AA came in, so hopefully I'll have it put together this weekend. I'm still trying to decide if I want to connect it straight to the stator wires, or go through the existing harness. I think I would have to do the blue wire mod if I went straight to the stator.

I have a fair bit of leftover 1/8" aluminum angle, c-channel and 1/4" plate from a homemade CNC build. I couldn't get the plate to bend without cracking, so this is what I came up with:



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post #8 of 12 (permalink) Old 10-06-2017, 09:53 AM
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Looks good.

It's my advice to bypass the stock r/r harness, it will save a lot of problems.

You can still use the stock headlight setup if you want, but it's also my advice to do the blue wire mod. Any function you can remove from the Junction Box, the better off you'll be down the road. It just eliminates a future failure.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #9 of 12 (permalink) Old 10-06-2017, 12:35 PM
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That thicker aluminum plate will be a really good heatsink for the r/r.

I just taped up the stock r/r plug and tucked it out of sight, haven't seen it since.

The MOSFET wiring is really simple, 5 wires and you're all done, if you don't use the stock wiring. 3 stator legs, one hot, one ground to the battery.

If you want the headlight relay function, you just need to connect that wire (yellow/red?) to one leg of the stator wiring. Double check me on that wire color. The AC volts from the stator is what triggers the headlight relay.

I originally had my headlight relay connected, but ditched it before I even rode any. With the AGM battery, it's never been a problem.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #10 of 12 (permalink) Old 10-11-2017, 05:47 PM Thread Starter
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Quote:
Originally Posted by Spockster View Post
Looks good.

It's my advice to bypass the stock r/r harness, it will save a lot of problems.

You can still use the stock headlight setup if you want, but it's also my advice to do the blue wire mod. Any function you can remove from the Junction Box, the better off you'll be down the road. It just eliminates a future failure.
You were Right.

This is my Dad's bike and he wanted me to change as little of the wiring as possible. I connected the r/r to the old wiring. I noticed an improvement from cold, but as the bike stayed on and warmed up, the level of charge decreased to the point of not charging (by the end it was at 11.7 volts @ 3k rpm) The stock wiring was extremely hot to the touch. The wires are tiny in comparison to what came with the r/r. I think they get so hot that the resistance in them goes up, limiting the current through them.

I wound up connecting the r/r directly to the stator using 10 gauge wire and did the blue wire mod. I get 14.5 volts from cold to warm up, then it goes down to 13.2-13.5 when the cooling fan kicks on and stays steady there. The bike runs pretty hot, so it may need a tune-up/carburetor cleaning and adjustment.

It doesn't seem to have any trouble starting with the headlight on, but I was considering adding a toggle switch just in case he ever had trouble starting the bike.


Last edited by manyhats07; 10-11-2017 at 06:13 PM.
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