electrical problem with 83 xj750 midnight

I recently bought a 83 xj 750 midnight. the PO thought the starter clutch was out so I researched what a starter clutch even was and figured out that it most likly was not that. So once I got it home i found that with a fully charged battery the only thing i get from it when I turn the bike on is the rear running lights. some times I do after I hit the starter button but rarely.

I turn the key to on and I get nothing then i thought well ill check the fuses/just replace all of them in case. and then they started burning out after i did that. .....? WHAT? it made no sense because I put the same fuses in there. so I checked the wires around the fuse box and there were two wires touching, they must have melted some time.

so I wrapped them in electrical tape and checked the wires about 5-8in up the harness(unwrapped) no problems and any where i thought there may be a short i wrapped them(i was just trying to be over cautious).

I have no clue what any of the fuse's are for and I have asked with no answer what they are. I know the one closest to the battery runs to the starter relay but thats all I got. and I only have 3 set up for fuses then to night in my rummaging fount a cable that ran up to the fuse box had a connector on it then it looped back into the harness from the same direction.....? was this once another fuse set up? I also took apart the starter button and cleaned off the corrosion.

any help is awesome. if I left something out let me know.


Jake

 

i guess im on my own then....? come on where are the guerus for this one?

 

I'm sorry Nisom, I just checked in. Let's see what we can do.
I don't happen to have the schematics for an 83 Midnight Max but the 750 electrical system is more or less the same for a number of other years.
Finding melted wires is an indicator that you have a high resistance issue somewhere causing high current to flow through the wire and heat up, ergo melted wires. Corrosion in the wires and on the fuse block is a know problem area on these bikes. The short answer is to replace the wiring harness but that is more than just a quick fix so we'll settle for replacing the fuse block and the melted wire runs. It is an imperative that you get that fuse block replaced, the old ones cause all manner of gremlins that will bite you in the keaster.
The Main fuse is the one you located. I do not know what rating it has (my Seca runs 20 amps), perhaps one of our brethren will enlighten us... (hint hint hint gang!)
The other three should be signal, headlight, and ignition, 10 amps each as memory serves.
Be advised that the supply wire for all three of the 10 amp circuits comes from the same place (my Seca shows brown wire for them) so you don't need to get them back in exactly the same place, any one will do.
My Seca schematic also shows the down stream wiring for the Headlight to be Red w/Yellow stripe, the Signal us Brown, and the Ignition is Red w/White stripe.
I hope this helps, let us know how you fair with your efforts.

 

Yeah i found a wiring diagram for a 550 80-83 and it had the same colors listed.

the thought of replacing the fuse box has run threw my head so now with your advise i will replace it pronto. lets hope O'reily has one similar enough.
i actually had running from battery down 20, 15, (no fuse the guy connected the wires), 14....so im confused...but oh well.

thank you Robert I hope to get this working soon.....

Thank you
Jake

If any one else has something to add....please do...

 

take the seat and gas tank off. the wiring will basically be staring you in the face. you don't necessarily need a new fuse box. just simply replace with inline fuse connections. somewhere some wire or wires might also be grounding out. in which case y ou should see some melting or something along the harness. might even be in the headlight bucket also.

those bikes were old and not a lot to tear down. shouldn't be too hard to find a problem somewhere.

my bike has the fuse panel but only two fuses are still there. the other two have inline connectors now. that's how i got it.

 

Well. sir ...

Your story sounds exactly like mine.
When I tried to get my Midnight Max to come to life, ... nothing.
I replaced the Fuse Box.
Took ... forever ... to find the Power Relay substituting for a Safety Relay.
But, when I pushed the Start Button ... nuth-ing!

That's when I learned about how contaminated the Electric end of the Starter can get ...
And how dried-up and thick the Planetary end can get.

Make one of your first adventures ... overhauling the Starter.
The Starter won't turn if Carbon dust from the Brushes collects all-over the commutator-end of the Strarter.

And, ... many a Bike has got sold for not being able to get it to Start ... when all that was needed was just New Brushes for the Starter.

I know you want to get that Bike un-f*-*ed.
I'll give you two of the most important pieces of advice you'll need for unscrambling an Electrical Problem.

Get yourself a copy of the Genuine Yamaha Workshop Manual specifically for your Bike ... alone!

1983 XJ750MK Service Manual
P/N LIT-11616-03-39
$79.00 Print-on-Demand

And, then spend 12 measly dollars for THE Best 12Volt Test Light you can buy ...

The Legendary Cal-Van 72 Circuit Test Light & Sounder
http://www.rjtool.com/p-1354-circuit-so ... an-72.aspx

 

Thank you Snowwy I already have these things done but I will check the head light i like that idea. I was totally thinking if I couldnt find a box to fit I would just buy in line ones.

Thank you

Yikes $80 for the manual? I do have a volt meter so im good in that department. I do know that the starter works I didt jump it to make sure. i also jumped the solenoid so once I get the fuse's to stop blowing. I will check if its the solenoid or not.

Keep the ideas coming you guys rock

thank you
Jake

 

went to the store and bought a fuse box mainly cause it was 1/4 the price of buying in line fuses

 

The fuse block is a great idea however, be sure to seal the connections to prevent oxidation from starting the corrosion process all over again. This is primarily why I choose to use the water tight inline fuse holders.