25 Year old wiring and an air box.

[Anonymous]

Okay, so I decided to put the air box back on to skip the hassle of tuning the carbs for an engine I don't wanna hassle with. (I'll put the pods back on when I rebuild the 1000 engine and I'll tune it then) While putting the airbox back on I must've jolted something, because I fried the fuse instantly, and continue to fry it, as soon as the ignition is turned on. I unplugged the two available connectors under the tank ( a 4 plug one, maybe the gear position indicator, and an 8? plug one.) both are right next to the coils, still blowing the fuse. Okay, so it's in a wire that comes live when the key is turned on, and it's shorted, and its not in one of those connectors. I believe I pulled it loose when I was putting the airbox back on, or I pinched it putting the sprocket cover/clutch adjuster back on. So, can anyone shed some light on this problem? I really would like to avoid rebuilding the wiring harness, finals are coming

[Anonymous]

If your bike is like mine, I would look under the left rear side of the airbox, while seated on the bike. On my bike there is a bundle of wires that run from the fuse panel to behind the front sprocket cover. I know when I replace my air box, I have to use care at that position.

Dave W.

[argonsagas]

Jolting something inside the harness is highly unlikely. Harnesses are tightly wrapped and there virtually no movement possible. That is why they show so little flexibility.

You did not say which fuse is blowing, and knowing which one it is may help you to find which wires to check.


Most likely you have pinched something and the easiest way to find out what is to backtrack your efforts. This will mean pulling the airbox off, obviously, but I would suggest an additional step FIRST.

Take off the tank.

It is not a big job....just two bolts, an overflow hose, and fuel line/vacuum hose and two wires to remove (if you have a fuel gauge)

This will make everything much easier to see, which is very important.

You will be able to see whatever is stuck by the frame while the airbox is in place, and you may be able to identify the problem right away.

If you cannot identify it right away, then remove the airbox screws/bolts slowly, and watch them carefully to see if anything that was caught springs away. Examine all wires near the box.

Almost certainly this is where you will find your problem.

[Anonymous]

Well, the 78 750 doesn't have a fuel gauge, nor multiple fuses, I only have 1 fuse, the main. Took off the tank, disconnected the two plugs that are accessible, still blows, nothing **appears** pinched, the entire wiring harness moves somewhat freely, the few things I guess I didn't disconnect are the neutral indicator, and the oil pressure indicator wries, but the indicator wire, as I understand it, can ground out without problem, that just lights the light (it's not a live wire) I have an aftermarket Martek 440s Electronic ignition, and that did get pushed by the airbox, as well as the portion of the wiring harness that runs along the top of the battery box to the tail lights. Tomorrow I'll disconnect some more stuff and pull at other things, ect. I'd just like a better starting point.

[Anonymous]

If you have an after market ignition, start there. Actually on these old bikes if you don't have an after market ignition, you need one.

Ok...look for an uninsulated connector on the ignition module. Sometimes you can push the wiring around and cause a connector to ground against the frame. The battery box is directlt behind the air box so start with the positive lead from the battery. Make sure it is not grounded against the frame in a hidden location. The ignition switch lead runs up to the key and back. This is inside the wiring harness and usually has no problems. Ther are some other useless things in the wiring harness but they should not be the problem. You should find the problem around the battery box or between it and the air box.

Did you have the tank off? Their are ignition leads to the coils both are two wire connectors and marked Black-Yellow stripe, if I remember correctly. I have had these come apart and cause a short. Keep us posted on this thread, I will bet it is something real simple.