Fixing up my XJ750J Maxim

Hello everyone,

I just got an '82 XJ750J Maxima as my first bike to learn on (both mechanic and riding) and the first thing I'm doing is a full inspection to make sure things are in order, it runs just fine (a little rich) so I'm looking at the electrical bits first, I've found a few issues and I was wondering if someone can give me some info on how to go about fixing it. You'll notice that contact corrosion is a common issue

1) The Horn doesn't work at all. I've checked the voltage at the horns (pulled the wires and used a meter on the wires itself) and it's 7.8-8.3V when I press the button. I think it's supposed to be 12V, what should I look at to fix this? - Fixed - Corroded contact inside horn, replaced with Harbor Freight horn.

2) The turn signal doesn't blink, I turn it on and it stays steady. I've read on here that it may be the flasher relay, if that's the case will I have to replace it or can it be repaired? I've read this which is pretty thorough. If it is the relay, would I better off just replacing it with the one from this thread? - Fixed - Contacts were corroded, cleaned with CRC then coated all connecters with dielectric grease.

3) The rear left turn signal doesn't turn on, I checked and it's receiving voltage. I believe the bulb contacts are corroded as if I put the bulb on the other side it lights up. How can I clean the contacts inside the housing? Doesn't look like I can pull it out. - Fixed - Cleaned contacts with CRC cleaner

4) The fuse box was replaced with blade fuses and a couple others (I read this is recommended) but I'm a little confused on the circuits. I tested them by pulling the fuse to see what went where, and the one that I believe is for signal (a S was written on it) will turn off the instrument panel (same as when I pull the Main fuse) instead of just the turn signals, is that supposed to happen?

5) There's corrosion pretty much everywhere, what's the best way to clean it up? Fixed - CRC all up in them wires

6) The rear brake pedal is connected with this, should I replace that cable? Edit Looked it up in a manual and Appears I'm missing the return spring, is that correct? Fixed - Purchased replacement spring

7) I think some of the above require looking at wiring under the tank, how do I remove that? Should I drain the fuel somewhere first? Educated Remove bolt under sear then clamp fuel tubes and disconnect.


I think that's what I've found today. I did manage to drain the battery while testing all this so I dropped it off at a shop to charge, should I just leave the bike running or is there a better method to testing the wiring?

 

Re: Fixing up my XJ750J

I can help with a couple of things. First off, your bike is a *MAXIM*,---not *MaximA*. Were sticklers for that kind of thing around here.
If you have corrosion on some electrical contacts, get a can of CRC electronic cleaner. This stuff does a good job of removing corrosion on electric contacts. Just follow the directions on the can. This might help with some of your problems.
Get an electronic test light or voltmeter. These are a must for tracking down electric problems. Good luck.

 

Re: Fixing up my XJ750J

Thanks for the info! The PO called it maxima so I just stuck with it

I've got a tester and multimeter. I was using the meter most of the time to check the lines, seems that voltage drops at each connection so I think I'll need to give all the contacts a good cleaning with what you recommended before I do anything else.

 

Re: Fixing up my XJ750J

I'm trying to figure out what part I need for the rear brake, I've found This one on eBay but that spring doesn't look quite right as I was emailing someone about the brake spring and there's looked like this.

Which should I be looking for or does it not matter that much?

 

Re: Fixing up my XJ750J

You will also have contact points inside the right control/switches housing that could be the cause of the voltage loss.

If the bulbs have been changed to lower wattage units. It will cause this problem. The relay requires approximately 54 watts of current to make the bulb blink. Standard 1156/1157 automotive bulbs should work fine.

Many guys have switched over to an electronic relay to avoid this problem, but you will most likely lose the self canceling feature of the signals in the process.

The wire lead can be shoved out from the back, but the problem is more likely a loss of the ground. Make sure all mounting nut/bolts are tight, and the inside of the bulb mounting is free of corrosion.

Covered by wwj750.
Also. Once clean. Use dielectric grease on all electrical connections to to help keep them from corrroding again.

Once you remove the seat. The tank will be held on by a bolt at the rear of the tank. Lift up, and rearward to remove the tank. Remove fuel, and vacuum lines from the back of the petcock.

That is why they become PO's. They don't know the difference between a car, and a bike. :lol: :lol:

The spring in the ebay pic is the correct spring. You will need the long straight section to clear the frame, and swingarm.

Good luck
Ghost

 

Re: Fixing up my XJ750J

Thanks for the info! I ordered the spring which will be here Saturday. I chose a bad week to buy a bike, family has been visiting and I've barely had a chance to touch it. I just spent 20 minutes in the dark using my car to light the bike while I fixed the turn signal.
After cleaning the contacts it turns on now but doesn't blink, I didn't look at what type of bulbs were in there so I'll examine it tomorrow morning.

When you say right control/switches housing is that the instrument panel? How do I get that open? I'll need to open it to replace the speedo cable once I get one.

 

Re: Fixing up my XJ750J

The switch housing on the handle bar on the right side. There are screws on the bottom that will seperate the two halves of the housing so that it can be removed.

Also note that there will also be contacts in the left switch housing that should also be cleaned.

Ghost

 

Re: Fixing up my XJ750J

I went through and gave all the contacts I could find for the horn (didn't locate the positive quick disconnects yet) and I'm now seeing 11.3V coming through but the horns don't even make a sound.

I also cleaned all the bulb contacts for the signal lights and verified they were 1156/1157 and the they still don't blink only turns on and stays steady. I got a couple relays and swapped them out without any improvement. I did notice that when I rev the throttle that the relay switches again and shuts off the lights (even the signal light on the IP goes off) so I believe that's a grounding issue.

Right now I'm considering redoing the wiring for the signal/horn and put them on a separate circuit with a fuse as there's something going on with the wiring.


Also, on the rear brake I replaced the spring on the switch (the wires on the replacement were too short), I did notice that on the brake where the torque bar connects with the drum brake there's a little arrow (wear indicator?) which barely moves when I hit the brake. If it's not moving much, would that mean there's isn't much left?

Edit: I looked it up in the manual, looks like I need new brake shoes. Is there a recommended vendor for buying them? I'll check XJ4Ever...

 

Re: Fixing up my XJ750J

Assuming you have an 82 XJ750J that still has the rectangular "Atari" unit (with speedo, tach and warning lights), the speedo cable screws into the back of the speedometer threads which stick out of the Atari slightly.

No need to disassemble the Atari just to change that cable. There is a good picture of it sticking out here as well as a tutorial how to dissemble the Atari:
http://www.xj4ever.com/gauge%20cluster%20breakdown.pdf

 

Re: Fixing up my XJ750J

Hey there Ashex. That little arrow is indeed a wear indicator. It goes like--not moving much=lotsa material left. Moving alot= material wearing thin. BTW, you gotta pull the wheel & visually inspect the shoes for delamination. This is the very first thing to do when you buy an XJ. Delamination is when the braking material separates from the carrier & can cause the rear wheel to lock up at any given moment. This is a very serious safety concern & you gotta put this at the top of your things-to-do list right away.
As for the electrics problems, are you testing with the motor off? Could be a weak battery. The charging system on these bikes dont kick in til around 2500-3000 RPM. Try testing the signal lights with motor running at the listed RPM's. Also check the voltage of the battery. If it shows less than 12 volts, maybe it can be brought back if the fluid levels are low. If this is the case, top off each cell to between the MIN & MAX lines with DISTILLED water & throw it on a low amp charger til its fully charged. Hope this helps-good luck.

 

Re: Fixing up my XJ750J

Thanks for the advice, I've looked into the rats nest a couple times and completely missed that the speedo cable is right there. I have the "Atari" unit so that'll be a quick fix although I may open it up so I can adjust the odometer (need to add a couple hundred for the PO) later.

Thanks for describing how the indicator works, guess I'll be okay! I read the thread about delamination recently and I'm definitely going to pull the wheel to take a look, was going to do it yesterday but the wife threw a birthday party for me

I've been testing with it on and off, after I killed the battery the first time I've been sure to test the electrics when it's running. The battery does show 12 Volts when it's off and the alternator works as it measured ~14V when it was running around 3000 RPM. What size battery should I be using in the bike? It's been replaced at some point and seems a bit small for where it's sitting.

 

Re: Fixing up my XJ750J

Don't waste your time worrying about this. For the age of the bike it will not make any difference. Your could very well do more harm than good trying to change it.

On the horns you can test the horns by running a wire from the battery postive side to the horn, and another from the horn to the battery negative side. The horn will honk if it is good. You will not find any other quick disconnects in the wiring for the horn system.

The stock signal lights will be grounded through the metal housings. Make sure that the mounts are clean and tight also.

Ghost

 

Re: Fixing up my XJ750J

got a pic? welcome!

 

Re: Fixing up my XJ750J

First thing, your not blinking turn signals can be from both a weak charging system or just not all the bulbs working, make sure you have good bulbs in the signals and the battery is charged first, non-flashing may fix itself. Also, I would advise cleaning the contacts inside the switch on the left handle-bar, that gets really messed up.

As far as the quote above, I don't recommend leaving the bike running while doing electrical stuff. For one thing, it won't do any good, the battery will still drain unless you rev it over 2000 rpm constantly. Also, your bike is AIR-cooled, not ever a good idea to let it run while not in motion for any length of time. If you do that, get some fans to blow on the motor, to simulate motion. What I do is leave a trickle charger connected to the battery if I'm testing a lot of stuff. You can get one cheap at Harbor Freight. Or get a good battery charger, still fairly cheap, they are a great thing to have.

 

Re: Fixing up my XJ750J

O.K.-confused here. Plz tell me what in the world is wrong with checking to see if the turn signals work @ 3000RPM? I was asking if he was checking the turn signal operation without the motor running.
Maybe my XJ is weird because when my battery is nearly dead, I may have no light, or just a non-blinking light til the motor revs enough for the charging system kicks in.

 

Re: Fixing up my XJ750J

Nothing is wrong with that, wwj...I'm not sure who your last post is directed at, but I'm assuming it's me. I wasn't talking about what you said, I was talking about what Ashex said, that's why I quoted it.

Ashex was talking about killing the battery from having the key on and testing things, and was asking about LEAVING the bike running throughout all his tests to keep the battery from dying. As far as what's wrong with that, I already said it.

As far as the light not blinking until the charging system kicks in, that's pretty much what I was trying to say about the whole make sure your battery is charged thing. Same difference.

 

Re: Fixing up my XJ750J

Yowza, I'm getting lots of attention

I'll take a pic once I've cleaned the bike up a little, the PO has dropped it many times so she doesn't look too pretty

I'll open the alternator and look at the brush size when I have a chance, I did check that all bulbs work and the housing has been cleaned up in each of them. I also cleaned the inside of the switch on both handlebars with CRC (didn't use a q-tip as I didn't see any significant corrosion).
I'll look into buying a trickle charger, I've been working in a parking lot but I can always park it next to the door to plug it in. Just so you know when I'm working on the electrics I disconnect the battery, I only connect the battery to test a fix


To clarify, I would rev the engine to 3-4K rpm when testing the signals as I wanted to see if the alternator would kick up the power enough to make it run, so far all that's happened is the relay clicks again when I rev it turning off the lights instead of flashing. According to the manual the self-cancelling unit should leave it flashing for 10 seconds at low speeds then shut it off.

 

Re: Fixing up my XJ750J

Electric problems can be such a PITA. The manual for your bike lists the battery as a 12N12A-4A & should fit in there pretty snuggly. maximikes suggestion for a trickle charger is a good one. Keep the battery charged & your bike will love you long time. Sorry for sounding crabby before, I got a thing goin on here that appears very similar to RickOmatics & has prevented me from ridin (& other things.)
Be patient & keep troubleshooting-you'll get to the bottom of this. maximike sounds like he's been around an electric circuit before. Keep askin questions & good luck. Have a great day, all.

 

Re: Fixing up my XJ750J

lol, yeah, I didn't mean to sound crabby either, I was up all night doing other things and checking the forum for a response to another thread. I have done more electrical stuff on my bike than anything else. I notice a lot of people hate wiring and you see a lot of "I can do anything but electrical" comments. Me, that's my favorite thing, and not just because I'm working on a degree in electrical engineering

(my second degree, but my first is in Linguistics, so not really useful for working on bikes, except maybe reading Japanese manuals, lol)

 

Re: Fixing up my XJ750J

Honestly, Electrical is the one thing I'm totally comfortable working on. I grew up building stuff with my dad (who's a EE professor), at one point we wired his uncles house for solar power. I'm not really intimidated by this bike more incredibly irritated, I don't feel like pulling the take to run a new circuit but if I have to I will

 

Re: Fixing up my XJ750J

Hooray for double posts!

I took all my horns (I got a couple fancy chrome ones from a xj650 with the relays) and tested them against my car battery to take the bike completely out of the equation.

Of the four, only one works. The good one is from the chrome set (and probably not the one I tested on Saturday) and when I hooked it up to the bike and pressed the button it went off! So no horn wiring issues, just bad horns. I'll buy a pair from harbor freight (my brother got a pair he really likes that should fit fine) for that.

So that's one major issue out of the way, now for the signal lights!

 

Re: Fixing up my XJ750J

The horns I bought ended up being about double the size of the stock ones so I was only able to fit one in, I'll get a couple brackets to fit them elsewhere later on. They work when the bike is running (when off the voltage is too low to set it off, makes a little popping sound) so that's taken care of.
I went through the wiring harness behind the headlight and coated each contact with a thin layer of dielectric grease and like magic the turn signals began flashing again! I did the same to the quick connects for the rear lights too.
There is still some resistance somewhere so I'm going to go back through the turn signal housings and clean the contacts again as when the bike is back at idle they stop flashing, it's only when the bike is in motion that they work (then again, it is idling a little low so I'm going to adjust it tomorrow).

Now I did notice an issue that wasn't there when I purchased the bike, the battery and headlight warning lights turn on. I can tell that the Low-beam doesn't work but the high-beam does, any idea why? As for the battery I think it's complaining about a low-level which is odd as I had it on a trickle charger, is it possible the battery is faulty?

 

there's a 3 conductor plug that comes from the alternator in the area to the left of the battery, maybe under the seat, it likes to corrode and melt, make sure you check it out.
the low beam? maybe the bulb is burned out.
the battery warning signal comes from a electrode that plugs in one of the cells where the water goes, white with red stripe wire, if you don't have something like that, Chacal sells a little circuit that puts the light out and monitors the charging system and battery. or just put the w/r wire to batt +, crude but effective.

 

I'll check that conductor plug tomorrow, I don't think the bulb is burnt out as it lights up when I switch to high-beam but then again I could just not know how those types of bulbs work.

Thanks for the info on the battery, I've wondered what that wire was when looking at schematics/diagrams. I'll see if I can locate it and figure something out for it.

 

As far as the battery warning. The bypass Polock mentioned that Chacal sells, I'm sure his is much more "professional looking", but you can make the same thing yourself. The thing is a lot of these bikes don't have the sensor that goes into the battery cell anymore. If you have the white wire with a red stripe that trails off to nothing, somewhere in the area of under the seat, that indicates the sensor is gone.

Here is the bypass: take 1/2 Watt resistors adding up to about 2k Ohms, (as you are electric savvy, I'll assume you know resistor code and attach those to the white/red sensor wire and solder it to a keyed hot wire, I used the taillight wire, since it's conveniently located under the seat. The great thing about this hack, unlike some of the others, like the bypass of the HEAD warning I had to do, is that it still functions. If your battery gets low, you'll get a BATT warning, even with this bypass, since it won't send the full voltage to the computer. Mine was sending a warning just recently, until I put the battery on the trickle charger, new battery just never was charged enough before, I guess.

 

I also put the harbor freight horns on my 750 max.

What I did was re use the original mounting brackets. Then just use a few washers to have them sit a bit further back.

I'll try to get a pic.

As for wiring, use the relay!!! These horns suck alot of juice.
I ran a jumper between one if the wires going into my blade type fuse box over to an unused bank and then ran the power from that to the relay. It popped a 15a fuse.

So deff use the relay, lol.

But they're decent horns, wayyyyyy better than stock.

 

Oh and I cut the threaded tab off the top of the horn for clearance and painted the ugly metal part black

 

Thanks for the advice, that is pretty easy to do, I'll go pick up a batch of resistors and wire that up.

That was my original plan but the screws were spaced too far apart for the bracket to fit, if you can take a pic that would be awesome.

I'm assuming you used the relay the horn came with? I plan on doing that later when I figure out how to attach both horns, since only one is connected I should be okay running it on the stock circuit.

 

Yeah the relay that came with the horns. I'll try to pull the gas tank and write down how i wired it up but i cant promise that as i'm going out to colorado for three weeks leaving at 4am tomorrow, lol.

But to explain how i used the original brackets, One of the holes lines up perfectly. Then, i marked where the other hole in the bracket would line up to be and then i marked a hole there.

I then took the horn apart and drilled a hole in the metal lip where the screw sat. I then Riveted the horn to the original bracket through the hole that i drilled.

I then Drilled out a recess in the plastic "horn" piece, so that the head of the rivet would not keep the two horn pieces from coming together.

Then, put all the screws back and boom! done!

As for wiring, i just took a wire from my fusebox that was hot when the key was on and ran a jumper to an empty place on my fusebox. I then ran that to the relay/horns. but the wiring i cant remember exactly. I'll try and remember to look before i leave though.

Heres the best pics i could get installed on the bike with my crappy phone, lol.

 

oh and once i had taken them apart and stuff the adjustment was off, so you have to pull the silicone off of the adjustment screw and then turn it to where you want it, and then i used some liquid electrical tape to fill the hole again so it wouldnt vibrate and change on me

 

Oh! and i had to dremel the edge of the plastic horn part so that the bracket could sit flush, you can kinda see it in the last pic

 

I had originally been worried about the plastic being so close to the valve cover, but they have been on there for about a month with no problems.

 

Thanks for the write-up! I'll start on the horns tomorrow. Today I wired up the battery sensor, turned out it had been connected directly and I had forgotten to reattach it the first time I pulled the battery.

I bought a 1/2 Watt 2k resistor and wired it in and here's the resulting beauty:



I kinda jacked up the soldering job but it holds together pretty well, the shrink tube will keep it in place and protect it. I put it in and I think it's working, once again I forgot to turn off the lights so the battery is back on the trickle charger.


Edit: I rode it around after charging it, interestingly the low-beam headlight works now so that warning light went off. The Battery warning light also went off after riding it for a little bit so all is well on that front!

Regarding the signal, it still stops flashing when the rpm drops. I turned it on while on the highway and let it flash for awhile, the auto-cancel isn't working either. Should I keep chasing down the problems or just swap in an electronic relay? I'm partial to the latter.

 

Old style 2 pin flashers cannot handle the low voltage.. FYI I managed to fit a CF13 3 pin to my xj750. Brown is + and connects to B+ pin, the Brown/White is your BULB side which connects to L pin. Lastly, you need to connect E- to the frame or and earth wire. You can leave the Yellow/Green wire, which is your auto off trigger.