82 xj650 blowing main fuse

Alright so im having some issues with my 82 xj650. The main fuse keeps blowing. Now i already replaced the glass fuses for blade types a few years ago because of the obvious issues. Until this year ive never had much in the way of wiring issues with this bike.

Ive chased the wires up to the headlight and ignition switch with no luck in finding any cut or crossed wires. Ive pulled every plug relating to that main fuse with no change except when pulling the the plug to the solenoid beside the battery or to the rectifier. The battery plug would obviously kill power to the main fuse out of hand. I tried chasing the wiring coming back out of the rectifier with no luck finding any cut or crossed wiring. I picked up a new rectifier figuring thats where the short had to be but no dice the fuse still pops as soon as you insert it. This all happens with the ignition off.

For shits i cut the wire coming from the main fuse where it Ts off to the rectifier leaving everything else hooked up. When that was done the fuse was fine the lights came on and the starter would spin over. So everything worked as it should short of what was going to the rectifier. So now im at a loss. Is there a common place that wires rub through and short in that circuit i may have missed?

 

Did the fuse blow with the new rectifier / regulator disconnected?

Check that wire to ground using a DMM, it should read shorted if the fuse is blowing.

Disconnect the rectifier, if the short goes away then check the diodes in your new rectifier. If the short stays with the rectifier disconnected then time to look again for a chafed wire to chassis.

Is this your trailbike? Welding?

 

maxim or seca?

I ask because in the 82 seca the red wire from the fuse connects to the regulator after the ignition switch and the maxim connects before the ignition switch.

 

I am always wondering why Yamaha chose to make the wiring harnesses so different when the model features are so simmilar. A tale lost to time I'm sure.

 

makes no sense to me. maybe just a different engineer working on the different models

 

I do think your trouble is in the Vr check the diodes using this diagram and your meter set to diode
check the old and new one


also ohm out your alternator you could have a short in the windings

also check the diodes in the diode block

 

No this is my maxim street bike. With the rectifier disconnected the fuse wont blow. Coming from the battery through the solenoid into the fuse. Leaves the fuse and there is T off with one end running up the frame to the ignition switch etc. The T off runs over to the rectifier. With the new rectifier hooked up it still blows the fuse. I cut the wire running from the main fuse to the rectifier to eliminate it from the equation and with the rectifier still hooked up and just that one wire disconnected everything on the bike will come on except what has to run through the rectifier to work. Which was why i had assumed it was the rectifier in the first place when i ciuldnt find a bad wire

 

do you get the bike running when when you cut the wire?

I am not sure on this but I think the battery charges through the main fuse when the bike is running.
could be alt is putting out to much voltage or a bad battery .

ohm out the alternator. and diode block just because it is connected to the alt

what are the chances of having a bad Vr and buying another bad Vr?

are any of the connectors melted at the vr?

 

I didnt go that far with it. I spun it over a few times to make sure the starter was kicking but i neverr actually tried to start it like that. I figured the coils probably ran through the rectifier at some point and wouldnt give me spark if it wasnt getting power

 

Bike will run with rectifier unhooked. I'm also leaning towards bad rectifier as the red wire from battery to fuse only goes two places after fuse; main switch and rectifier. If bike starts and runs without blowing fuse with regulator unhooked you should test it out.

Correct.

Test procedure here:

 

Right which was why i picked up a new one but with that not changing anything im thinking it may be in the alternator windings. Ill un hook it today and try starting it. Then check the windings see if that gives me anything

 

Well tried starting the bike with the rectifier disconnected and it spins over but doesnt engage the motor. Ohming out the alternator im getting 63.7ohms. On the diodes i get .62-.61 on the original rectifier. .54-.545 on the new one

 

You have to check each diode individually for continuity on the rectifier. There's six tests you need to do and do it both ways to ensure the diode is functioning so a total of 12 tests.

 

Here's the instructions to check stator and coil:

 

My apologies if those came across poorly or short, I was forum surfing from my phone. The numbers you show for the "alternator" don't match anything in the book nor did you explain what you were testing. Same with the rectifier, there are a number of tests you need to perform and you are looking for continuity not resistance. I posted the two relevant pages from the FSM that should help. I assume you're not riding due to the PA winter, if you like to ship the rectifier to me for testing I'd be glad to test it out no charge both with a meter and on my bike if tests out okay. Shoot me a PM if interested.

 

Yeah it would help if the bike started lol. The starter spins over but doesnt engage without the rectifier hooked up also the rectifier being hooked up blows the main fuse. So how do i check the diodes acording to that procedure with the bike not starting and the rectifier blowing the main fuse every time i hook it up?

 

It should run without it hooked up if your battery is fully charged. When you say it doesn't engage, do you mean the engine doesn't fire or the starter is not spinning the engine? The test in the book are for testing the coil, stator, and rectifier without anything running or having voltage applied.

 

The started isnt engaging the motor it spins over but isnt kicking in to engage the motor. The one you just sent said with engine running increase rpm etc.... I did the tests without it running and like i said everything seems to be in a reasonable range

 

That sounds like a different problem. Is the battery fully charged? Can you put a meter on it and observe the voltage at rest and then while attempting to start the bike? We need to know that first. You might have a starter clutch issue if battery is good but motor is not spinning over. Have you done any work on the starter?

There is not one test per component. There are two tests for the stator and field coil. Can you post the readings for the Green to Brown wire and then also the White to White wire? The rectifier is simply a series of continuity tests in two directions to test the diodes, there are no acceptable ohm readings for that component.

It should run on the battery only, think of the bike having two power sources. The battery provides all power needed to start and run, once running the charging circuit will "take over" and feed the same circuit via red wire and charge the battery.