Kawasaki VN750 Forum banner
21 - 40 of 44 Posts

·
Registered
Joined
·
56 Posts
Great thread, made my rewiring project a weekend deal instead of a week or two slog through the harness when my junction box went pop and let the smoke out. I did take the time and clean up the whole battery area as well, relocating the starter solenoid and rectifier while I was at it.
Holy smokes! HardRock, I would REALLY love to get ahold of your notes on what you did and how! That looks AMAZING! Can you share with the group please? I'm especially curious about the distribution block wiring and where you got the parts that you used. I'm in the middle of this myself right now but am going to freeze until I hear from you.

PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE

:grin2::grin2::grin2::grin2::grin2:
 

·
Registered
Joined
·
9,465 Posts
Great thread, made my rewiring project a weekend deal instead of a week or two slog through the harness when my junction box went pop and let the smoke out. I did take the time and clean up the whole battery area as well, relocating the starter solenoid and rectifier while I was at it.
Yes, wow! That looks like the ticket.

Cue Dire Straits - "That's the way to do it!"

Bestseller right there.
 

·
Registered
Joined
·
196 Posts
Holy smokes! HardRock, I would REALLY love to get ahold of your notes on what you did and how! That looks AMAZING! Can you share with the group please? I'm especially curious about the distribution block wiring and where you got the parts that you used. I'm in the middle of this myself right now but am going to freeze until I hear from you.

PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE PLEASE

:grin2::grin2::grin2::grin2::grin2:
I really just followed what Mcinturff laid out with a couple tweaks to fit my bike, but give me a couple days to go back through all my printouts and stuff and I'll add that information to this thread as well.
 

·
Registered
Joined
·
196 Posts
Here's a schematic of what I did with the JB replacement.

A few other notes on the job:
-The RLU has been completely removed, the Blue/Yellow wire is the one that the blue wire from pin 8 (or 7 if blue wire trick has been done) would have been jumpered to when bypassing the RLU.
-The Black/White wire pin 14 now is equipped with a ring terminal and grounded to the same bolt as the motor ground.
-So far I've been using a 3 amp fuse for the USB charger plug but I haven't used it very much yet I may need to jump to a 5 amp is I try to use both ports as it's a 3.1 amp charger.
-The fuse box and new plugs came off of Ebay
-Similar fuse box. DC32V 4 Way Circuit Car Boat Auto Blade Fuse Box Block Holder ATC ATO Waterproof | eBay
-Similar plug set. 2.8mm 2 3 4 6 9 pin 50 Sets Motorcycle Electrical Wire Connector Crimp Terminal | eBay

That's all I have for now if I think of more I'll update this post.
 

Attachments

·
Registered
Joined
·
56 Posts
Great additions Hardrock. I also went through the entire harness and removed all excess wires from tail light harness to the headlight bucket. Including the same idea you had with eliminating the RLU and all of the excess wiring for it. Unwrapped, removed, rewrapped, unwrapped, rewrapped...... OCD is a bitch. Currently waiting on my new fuse block and relays to arrive. You've given me a couple ideas though....

I particularly like the idea of moving the starter relay and harness to the left side of the bike and mounting the new r/r to the right side of the battery box. I'm also going to flip the ignitor box so that the wires run below the starter relay, keeping most of the wiring on the left side of the bike.

With all of this being done as well as upgrading to a SH775 r/r, I think I'm going to keep the accessory circuits. Thinking I'll run a USB charger to the rear storage (toolbox), and run a lead to the headlight bucket in case I need it later. Probably going to fuse each lead separately though.

One thing I noticed is that the stock wiring for the stator is VERY thin. Sheathing for it is at about the 14 gauge mark, but I stripped it with the section of my wire strippers marked 20-22. The actual stranded wire inside has plenty of room inside the 20-22 gauge stripper which is kinda sad. If this is what's carrying all the current from the stator, I would think it should have beefier wires. Think I'm gonna rewire with at least 12 gauge while I have it apart. This may take a while as I only have an hour or so per day after work to get anything done and still have to make brackets for the r/r and the fuse block. I'll add my own pics when I'm done though.
 

·
Registered
Joined
·
56 Posts
So here's my pictures of how my wiring rework turned out. Right after I finished I went ahead and did the ignition coil relay mod. I wish I had thought ahead enough to work in the ignition coil relay/rewire as a part of the main harness rework, but.... I didn't. I guess there's all winter for that.
 

Attachments

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,437 Posts

·
Registered
Joined
·
97 Posts
Discussion Starter · #30 ·
I PM'd him. I'm thrilled that this thread has helped others fix the mess that is the Vulcan's wiring harness.

I'm thinking of making a new battery box sometime this summer so that the battery can be removed without pulling off the seat.
 

·
Registered
Joined
·
97 Posts
Discussion Starter · #31 ·
Update: I did some work to the Vulcan over the weekend. It started as replacing the coils and turned into adding relays and making some repairs.

The wire to the thermostatic switch was broken internally, so I peeled back some of the wiring harness and replaced the broken section. Also, I was having issues with the motor spinning slow so I removed some powdercoating on the frame and made a good ground. It now spins twice as fast.

Next I deleted the reserve lighting device which led to wiring up some relays to power the radiator, headlight, and ignition system. The radiator and ignition relay wiring is pretty straightforward. The real trick thing I did was use a 5 pin relay and hook up the blue/yellow wire that used to be the output from the reserve lighting device to terminal 87a, so now the headlight turns off while the starter is turning over. Pretty cool, eh? I also used a 5 pin relay for the ignition so if the relay ever fails I can move the pin from 87 to 87a and hobble it home.

Attached is the mockup for my relay panel and fuseblock. I’m going to look for some better fuseblocks to make for a more robust design. I’m also going to move the r/r to where the goat’s belly was originally mounted.

Auto part Engine Vehicle Car Automotive engine part
 

·
Registered
Joined
·
1,579 Posts
I've been mulling over that headlight mod for a while now. Did you wire the new relay in series or parallel with the starter solenoid? How much digging in the harness did you have to do to make that happen?
 

·
Registered
Joined
·
97 Posts
Discussion Starter · #33 ·
I wired it in parallel. I had already peeled back the harness where it splits off to go to the tailights and rear turn signals and bypassed the old headlight relay in the junction box so I just added a wire at the junction of the black/red and yellow/red wires I made previously and ran it to the new relay.
 

·
Registered
Joined
·
1,579 Posts
I wired it in parallel. I had already peeled back the harness where it splits off to go to the tailights and rear turn signals and bypassed the old headlight relay in the junction box so I just added a wire at the junction of the black/red and yellow/red wires I made previously and ran it to the new relay.
Cool. I'll add that to my to-do list.
 

·
Registered
Joined
·
1 Posts
I just replaced mine realizing it was 90 percent of my problem. Bike would crank fine but no power to the coils. Would run the battery down trying. Learned to wiggle the key after a couple times. But eventually the bike would cut out and run while riding.
you are my lost soul....lol I am having the same issue I'm gonna keep reading now..lol
 

·
Registered
Joined
·
97 Posts
Discussion Starter · #37 ·
I got a PM about the relay wiring, but it just disappeared somehow. I'll post info here:

Adding a relay to the headlight system is pretty straightforward. You can incorporate the removal of the reserve lighting unit or keep it in place. The pin layout is as follows:

Pin 85: Black/red (may be solid black on some bikes) or yellow/red from the starter solenoid circuit, tap into this circuit
Pin 86: Ground to frame or a ground junction within harness
Pin 30: Blue wire from junction/fuse box
Pin 87: Empty
Pin 87a: Blue wire to reserve lighting unit (same as pin 30, just interrupt the wire with this relay), or use blue/yellow or blue/orange from the reserve lighting unit removal article, mine needed the blue/orange

On my bike the black/(red) and yellow/red are soldered together after removal of the junction box, so I added a wire to that junction to trip the headlight relay. For the ground I peeled back some the of tape around the harness and found a crimped junction of ground wires and used that. You could just run an eyelet connector to the frame around the battery box.

For the ignition relay there is a junction of 4 red wires when peeling back the harness that you can see in my original post. You'll have to snip here and find out which one comes from the handlebar switch (it will have 12V with the key on). The remaining 3 wires will be powered by the relay:

Pin 85: Red wire from handlebar switch
Pin 86: Ground to frame or a ground junction within harness
Pin 30: White wire from junction/fuse box or new wire from battery with inline fuse
Pin 87: Red wires feeding coils and igniter box
Pin 87a: Empty, switch wire from 87 to here if relay fails or you lose power/ground from pins 85 or 86

Finally, the radiator relay pin-out. I haven't actually finished mine yet, but here is a guideline:

Pin 85: Self powered, split off of 30
Pin 86: Black/yellow wire to thermostatic switch
Pin 30: White wire from junction/fuse box if you want the fan to operate with key off to cool off radiator more, brown/white wire if not
Pin 87: Blue wire to radiator fan
Pin 87a: Empty, or just use a 4 pin relay
 

·
Registered
Joined
·
2 Posts
Let me preface by saying that this fix assumes you have a MOSFET R/R like the Compufire I installed on mine. You may need to modify some steps to keep the stock R/R wiring.

During the restoration of my '93 VN750, I unfortunately did not take the time to clean or modify the wiring harness to increase the reliability. I have been chasing electrical problems for about two months. My only modification as of a couple days ago was to get rid of the stock R/R and go to a MOSFET unit. Not long after I started having issues with the bike dying from losing power feed from the ignition switch, turned out to be full of dirt. My headlight also did not work, or the radiator fan. Next my starter solenoid died, then I lost power to the rear cylinder coil. Truly frustrating. The last straw was when I moved the main harness from under the tank to on top of the rear valve cover to make for a cleaner look, which interfered with removing the battery. So, after much research I decided to modify the entire harness from the petcock area to the back of the bike.

Figure 1

View attachment 39017

Pin 1: White/Red wire coming from starter solenoid. Main power feed.
Pin 2: White wire fed thru 30 amp fuse. Feeds ignition switch and the fan.
Pin 3A: Lead for 1st accessory.
Pin 3B: Lead for 2nd accessory.
Pin 4: Black/Yellow wire to fan switch, grounds the fan relay.
Pin 5: Blue wire, switched side of the fan relay, powers the fan.
Pin 6: Brown/white wire fed from the ignition switch. Has power in the "ON" position.
Pin 7: Normally left blank, used in bypassing the headlight relay. This is where the blue wire is moved to. Fed through 10 amp fuse.
Pin 8: Blue wire, switched side of the headlight relay, sends power to the reserve lighting unit.
Pin 9: Yellow wire from the stator, feeds power through a diode (since it's alternating current) to turn on the headlight relay. Once turned on the relay becomes self powered through another diode.

Figure 2

View attachment 39025

Pin 11: Black/red wire (may vary on some years), feeds power to the starter safety relay from the starter button.
Pin 12: Black wire (shows Y/G in the manual), grounds the relay if in neutral and/or the clutch is in.
Pin 13: Yellow/red wire, switched side of starter safety relay. Feeds power to the starter solenoid.
Pin 14: Black/white wire from the ignition module. Will kill ignition if not grounded.
Pin 15: Light green wire, to the neutral switch.
Pin 16: Green/white wire, to the kick-stand switch.
Pin 17: Red/blue wire, fed power through 10 amp fuse for the tail lights.

Upon inspection, it is evident that the headlight and starter safety relay circuits can be eliminated. Anyone who has owned a bike more than a month knows not to ride it with the kick stand down or start it in gear. Also, for anyone who has installed a R/R with leads that go straight to the battery, the stock R/R wiring can be gotten rid of.

IMPORTANT
Re-read that underlined sentence. Be aware of the dangers of accidentally taking off with kickstand down or starting the bike in gear!

Now that that's out of the way, we can determine how to get rid of the junction box entirely. The junction box is a never ending source of problems for Vulcan owners. I ordered replacement relays to fix mine, only to find that the inside was corroded. Good job Kawasaki engineers on the (lack of) weather sealing.

View attachment 39033

Another reason to do this is that by now your connectors are getting old and cracked, and tend to not survive being removed many times (as many Vulcan 750 owners have to do) to help diagnose electrical problems. Mine were pretty toast.
 

·
Registered
Joined
·
97 Posts
Discussion Starter · #40 ·
After verifying the solenoid is good by jumping the positive and/or ground off the battery, you need to determine whether you are missing positive or ground at the solenoid and work backwards from there, most likely positive. If you still have the junction box, first start by checking pin 13 for power while holding the starter button. If it checks out then check pin 12 for continuity to ground. If both of these are good then lastly check pin 11 for power (feeds from the handlebar switch) while holding the starter button. If all these tests pass then you most likely have a bad starter switch or broken wire in the harness to it (more common than you think).
 
21 - 40 of 44 Posts
Top