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Electrical - bare minimum to start

  • Thread starter Thread starter mfergel
  • Start date Start date
M

mfergel

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Bought a project bike - a 1982 GS750T. It had already been stripped down quite a bit.....no turn signals, no tach....essentially a starter switch, a speedometer, a headlight and a tailight. Attached a battery and I get nothing. Headlight doesn't come on, no crank, nothing. Fuses are ok. Tried two batteries.

I was wondering what the minumum wiring needed would be to just get to the battery to the start switch and the starter. I just want to make sure it turns over at this point.
 
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Most bikes have a key switch to get the power to the starter switch. You made no mention of that connection.

Look around the fuse box, there should be a 4-pin connector. One of the wires will be Orange. Connect that directly to the battery, the rest of the bike should light up. (This bypasses the ignition key switch.) Now you should be able to check everything else. Hopefully you are aware that you will need a rather large wire from the battery to the starter, it does not draw its power through the fuse box.

If you now have power but it still does not start when you push the button, pull the clutch lever. It is a safety interlock that is easily defeated by re-connecting two wires in the headllight bucket.

.
 
Minimum to start with is a WIRING DIAGRAM! You'll save yourself a lot of headaches.

In order to turn it over with the starter, you need:
- battery
- connection from battery pos. to starter relay to starter
- connection from engine to battery neg. via ground strap
- You can then short the poles of the starter relay with a wrench to prove nothing more than the battery has juice and the starter will turn.

In order to run the engine, in addition to the above you need:
- verify all lock-out circuits are closed: ignition, killswitch, clutch, sidestand, neutral
- verify fuse connections
- verify connections from igniter (points/CDI) to coils (neg.), and ignition circuit to coils (pos.)
- verify connections from coils to sparkplugs
- verify connection from starter switch to starter relay

This is all from memory (and I don't trust my memory, so you shouldn't either) - so verify with your wiring diagram.

- Richard
 
make sure all the earthing straps are there and have good connections.
if you just want to check the motor turns over for now, make sure you have a good earth from the battery to the engine and just short out the 2 terminals on the starter solenoid wit a screw driver, this will put 12v directly to the starter motor.
(make sure its in neutral!)
 
rcp said:
- verify all lock-out circuits are closed: ignition, killswitch, clutch, sidestand, neutral
Click to expand...
Alas, the sidestand switch is merely informational. It only turns on an alert light in the speedometer.
You can still ride off with the sidestand down if you ignore it. :oops:

.
 
Minimum. Wiring is a screwdriver across the top of the two big posts on the solenoid. Battery must b connected
 
posplayr said:
Minimum. Wiring is a screwdriver across the top of the two big posts on the solenoid. Battery must b connected
Click to expand...

and if you want to hear it run use a jumper wire from the battery to the orange, I believe, wire that goes to the coils. Or do what the other guy said and go thru the pigtail and power the whole bike. In reality you need to trace the source of your problem. If you don't have a service manual get one or check out basscliff's site see if your bike is in there. The wiring on these old bikes are fairly simple so have faith.
 
Thanks guys. I'm going to give some of those a shot. I do have the service manual. The problem with using the wiring diagram is that the wiring is no longer stock and is missing most of the components. I'm not even sure some of the items are original, such as the fuse box, etc.
 
jmlcolorado posted this picture in a different thread a while back. It's a good starting point to find out what the po did. This is the min you need to have you bike totally running. I had to do some wiring work on my bike and used this with 2 copies of the stock wiring diagram (You could probably find them on Basscliff's website). I found everything that MUST stay from the diagram below. On one I printed off ran a hi-lighter with what I wanted and on the other ran a hi-lighter on what was coming off. I jumped between the 2 because somethings popped out a little different if I was having a hard time. And I only clipped one wrong wire which I caught before it went back on the bike.

Also this makes everything really clear so if you're need to just hook up one thing or another you can see what you need. I also printed this off too. It's easier than turning your head sideways.


 
hahahahaha! I drew that for him, glad to see it's getting around.
 
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