Suzuki 2 Strokes

I am really stumped here.
Having spent two years rebuilding a 74 Gt750 from six boxs I have a problem.After hooking up all the wiring the fuse will blow when the alternator is plugged in.
I have narrowed it down to the green wire which hooks up to the alternator brushes, it is not the brushes as I swapped them out with my other 750.
Short of getting the alternator tested is there anything I have overlooked.

thanks.
Jim.

Hi,I blew a fuse on my Gt750A,still don't really know what caused it
Found the Ignition Switch to be faulty,& a burnt connector inside the headlight,the one that's connected to the "kill switch" also had some "added wiring" under the tank that the previous owner had used to power "driving lights" which I disposed of....took me a long time checking the harness with a meter,but got it all sorted in the end Just a matter of going through things till you find the culprit,having said that, electrics still a bit of a mystery to me,do you have a wiring diagram to refer to,it could be something simple,like a bad earth ?
Cheers,
GT750Battleship.

If you have built this up from a collection of bits, then just double check that you have made the right connections on the electrical panel - two of the connectors look similar and can be interchanged by mistake. As 'GT750Battleship' suggests, trace back the colour codes against a wiring diagram to be certain have the correct connections made first.

Not to state the obvious, but fuses blow because too much current flows.
Too much current flows because there is not enough resistance between the source & the circuit return path (ie. chassis). In this circuit, the resistance normally comes from the field coil (sorry I don't know what that value normally is, but I would guess it is measureable with a multi-meter on OHMs mode). The Green wire you mention, comes from the voltage regulator where power is switched on or off depending on the system voltage (ON if the system is LO, or OFF if the voltage is HI). Having said all that, & your statement that it's "the Green Wire" that causes your problem, maybe that wire's insulation has failed (got pinched or cut?) somewhere. To check it, unplug at the voltage regulator, and at the alternator. This will isolate that wire from everything else. Use the Ohm-meter to measure from the green wire to chassis. It should be OPEN circuit (infinite resistance). If not, the wire is "shorted" to chassis someplace. You could hunt down the exact location of the problem, or just leave the wire in place & de-plug it at both connectors. Once isolated, just replace it with another wire & connections at each end.
Good luck.

When I rebuilt my GT750 motor I had the same problem (maybe)... I kept blowing the fuse, and what I finally figured out was when I hooked the wire to the alternator, there is a insulator washer. It was on the wrong side of the wire, basically creating a dead short.. Your problem may be different, but its worth a look.. Good luck...

Allen .... Smokeless and desperate !!

I had a continuous blown fuse when I rebuilt my GT750B. Turned out to be a short in the tail light. Some how, when I replaced the tail light bulb, the problem vanished.

Not sure if this will help anyone, and I don't want to blow up anyone's bike! My dirt bike is 12-volt with a dynamo / starter. It came with a 25-amp fuse where the factory called for 15-amp. Whenever I touched a switch, the fuse would blow. I inspected and mapped all of the relatively simple wiring harness, but other than finding that the ground wire was not bolted to the chassis, it all looked fine to me.

In desperation, I purchased some 10-amp (rated for 32 volts) slow-blow fuses from Radio Shack. These are not the super-dooper-mega-slow-blow fuses that have actual resistors in them, but are a bit slower than the average glass fuse that automobiles use.

I am still on my first 10-amp fuse and so far nothing has fried. Your mileage may vary.

thanks for your help everyone, turned out to be a faulty insulator on the alternator,
Jim. :

How did you figure it out? Where in the alternator is the insulator? Good news, for sure!!

the green wire that is attached to the alternator carries current to the alternator and excites it causing the alternator to charge.
I swapped out the insulator with a known good one{ the insulator is attached to the bolt that holds the green wire to the brushes} hey presto it worked..