Main fuse/Positive ground problems

There might be a clue in the term "positive ground system" where the positive side of the battery is connected to ground (or earth if the manual is in British English). Other than that it works like any other system.

texasSlick said:

I need to clarify my earlier post regarding the use of a VOM to test for shorts.

Connect one meter lead to frame ground, and the other to the battery negative wire with the battery disconnected. You should have a patent fuse installed, for this test. Otherwise, remove the fuse and connect the meter lead to load side (away from the battery) of the fuse terminal (battery can remain connected in this way).

Confused yet?

Slick

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Lol, oh I'm definitely confused . So If I leave the battery connected, I just leave the fuse out, put the positive VOM lead to frame ground, and the negative VOM lead to the load side in the fuse terminal, which is the one furthest from the battery. I then set the meter to the most sensitive ohms option (which I think is 200 on the one I have), and I would expect to see zero or near zero. Then I start disconnecting things and wait to see the reading change. When it does, the last thing I disconnected is the problem area right?

Torontonian has the bypass figured. But eventually you will have to check the wire loom. Do NOT unwrap the whole thing and let it turn into a pile of spaghetti! Start at any practical spot and carefully slit the old tape wrapping. Then work the tape off for about a foot. Place one wrap of new stretchy vinyl tape around the wires and then proceed to unwind the old tape. Place a wrap of new tape (or a cable tie) every foot or so, or were wires exit the loom. Eventually you will have the whole thing unwrapped and visible. You may find wires melted together while in this process. I would just keep on until the whole thing is exposed before you decide to fix any melty stuff. By keeping the loom intact with single wraps of tape or cable ties it is a lot easier to keep track of what everything is. It might be an exposed bullet connector laying against the frame somewhere. The headlight shell is a great spot for shorts.

Russ

To save you getting through fuses at a fast rate you can replace the fuse with a 12 volt bulb. Any 12 volt bulb will do but a sidelight bulb (5 watt) is ideal. You need to connect it in place of the fuse so that the power flows through the bulb instead of the fuse. It doesn't matter which way round you connect it. If you do the light will illuminate rather than the fuse blowing when there is a short.

Connect the battery the correct way with positive to earth, red wire. If the light comes on the fuse would have blown but the bulb is now soaking up the current so you have time to disconnect things until the light goes out which is what you are aiming for. Obviously whatever you disconnect to make the light go out is where the fault lies. If you disconnect everything likely to cause a short and light is still on you have a short in the wiring loom.

If the fuse blows (or test light comes on) as soon as you connect the battery the most likely things to be faulty are rectifier, zener diode, 2MC capacitor, wiring.

The ignition circuit isn't connected until you turn the key on.

Good Luck

Ian

Electrical problems have been a part of my life recently but I have managed to get most problems sorted with assistance from Les and a good workshop manual.


Test light was handy! Best of luck to you.

Jg

Hey folks, an update for you:

I spent some time at the machine this evening. One of the challenges I have is that neither of the local stores sell wiring of any kind, or the things that fuses slot into (whatever those are called). They do sell fuses though, so I guess I shouldn't complain too much. So anyway, after checking each store I made a trip down to the town's dump and pulled a few decent looking wires out of a couple of the old wrecked vehicles down there. This was in case I wanted to try the bipass method that Torontonian explained for me last night, if I was unable to find the short today.

I used the VOM as explained by Slick and tried unplugging each component according to both his and L.A.B.'s instructions. The reading stayed at about zero (around 0.01 or so) the whole time. I think I pulled everything except for the horn and the back light, but I did wiggle the leads on the back light and it had no effect. I followed the ground wires as suggested by Ashman, but I didn't quite finish exploring that scenario as some of the wiring goes into some very difficult to reach areas. I tried wiggling the wiring in various places all over the bike and that didn't provide any clues.

Anyway, the sun was sinking in the sky and I felt like I wanted to see some kind of progress so I decided to try out the bipass method to see if I could get anything to happen. So I got the dump wires I collected earlier, as well as the negative lead off the bike which has the fuse slot on it, (which the previous owner had cut off before and had taped back on - so I didn't have to do damage to use it). I carefully connected this to my negative wire and prepared everything. I pulled the plugs, laid them next to the spark plug holes, connected the plug wires and my bypass wires - checking everything twice before connecting the battery. Then I climbed onto the bike and gave her a kick... and nothing.... I was about to push the bike over the bank (kidding) when I noticed my ground wire was a bit loose so I gave it a poke and the plugs sparked! I made sure it was connected well and climbed back on and gave her another few kicks and I got beautiful sparks on both plugs every time !!! I haven't tried to start her yet as by this time it was dark and I want to make sure the oil level is good and that everything is connected well before I do, but I'm very happy at the moment. This is the first progress I've made so far, and I'm left feeling hopeful that this machine might run after all. I'll sleep good tonight, and I should have lots of time to work on her over the weekend.

If all my dreams come true and I am able to get her to run like this, how long of a ride can I go on before the battery dies?

Thanks so much for all the help with this so far!!!!

have a good sleep tonight , tomorrow the machine will breath fire , good luck ... are you related to the famous Ben Brake living in Truro NS originally from Nfld. ? ... it's a long shot I know but just had to ask , small world right ?
Craig

Thanks for the luck Craig, I will need it . And, I haven't met him, but if he's a Brake from Newfoundland we're almost certainly related. I'm originally from the island also, and from what I understand all the Nfld Brakes can trace that side of their family back to a couple of brothers who settled there in the late 18th century. Small world indeed!

Supercat said:

If all my dreams come true and I am able to get her to run like this, how long of a ride can I go on before the battery dies?

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If you have a full charge, and if you are running without lights, you should be able to ride it around enough to get a grin on your face! :mrgreen: :mrgreen:

Seriously though, it really depends. I would think you could run it at least an hour, no problem.

See this thread. how-long-will-motor-run-without-charging-battery-t8187.html

IF your main fuse blows instantly with the key OFF, you have some sort of dead short. That is probably a burned or skinned wire that's now touching ground...

IF that's the situation, don't even put the battery in the bike. INSTEAD, hook up your tester to the battery wires (with the fuse installed) and set the tester to it's continuity setting, which emmits a tone sound when their's circuit continuity. Then open the headlight shell where the rat's nest of wiring is located.

So, now you have an annoying tone coming out of the tester because it's detecting your electrical short. Move the wires around that are in the headlight to see if one of them is the grounding you out. You can remove bulbs to see if that turns the tone sound off too. The capacitor (blue thing on a spring behind the battery, can sometimes press it's terminal wires against the fender (mine did) and short out the bike. Go around and start disconnecting things, one at a time. If the tone goes off when you disconnect something, you've found the circuit to trace.

Once you turn the key on, certain circuits are suposed to be continuous, so the tone made by your tester no longer indicates a faulty circuit. It indicates both operating circuits and short circuits, so using the continuity tester with the key ON is no longer a binary result of "good" or "bad" indicator.

... this method gives you a starting place to maybe find that skinned, bare, or grounded circuit. good luck HTH

If you "git er running" and want to ride it some, and who wouldn't, disconnect the alternator wires. It is possible, that the alternator will try to feed the short in lieu of the battery, and "smoke test" something.

Slick

I rode 40 miles with no charging system a couple of years ago (Trispark electronic ignition) and there was no indication that the system was loosing power when I got home so you can certainly ride around a fair bit on the battery just to have the bike run. FWIW, an original points system would probably run all day on the battery with no problem.

Hey folks, another update for you:

Finally had a bit of time to spend with the Norton today and I decided to try to get her to run using the bipass method. I used electrical tape to try to tuck the harness wires away (temporarily until I go back to finding the short) and arranged my bipass wires so that they won't get hooked on anything etc. I topped up the oil, put the gas tank back on , filled the latter, connected the battery to my bipass setup and gave it a couple of kicks to make sure I was getting spark. I was. I pushed the carb lever down. Then I turned on the left fuel line, kicked it over maybe ten or a dozen times and all of a sudden she fired up, and for 3-4 glorious seconds she ran like a dream, and sounded just amazing! And then she cut out... I kicked her over and over, and then my neighbour came out and gave it a try but she wouldn't fire. I discovered that the positive wire had come loose from the battery so I sorted that out and we tried a bunch more times but no luck. I figured we had her flooded, so I decided to give her some time to recover. I brought the battery inside and put it on the charger, waited as patiently as I could, and an hour or so later I went back out connected the battery and tried again, but no luck... I'm getting sparks, but she doesn't want to run yet...

Any idea what I'm doing wrong? I've just been turning on the left gas line as per owners manual instructions. I've been putting the carb lever down, though I put it back up after it started that first time. When I came out the after waiting an hour I put it back down again. I so badly want to go for a spin !

As you said you "pushed the carb lever down.." (singular 'carb' and 'lever') does it have a single (Mikuni VM?) carb, not twin Amal concentrics?

Yeah, just a single Mikuni carb with lever

Get it sorted before you take it out for a ride, you don't want to be stuck on the side of the road somewhere, I know it can get frustrating for you and wanting to ride it but get the problem sorted before you do, if it was my bike I have all the wiring ripped out pulled apart and re wire the whole system from scatch, its not really a hard job to rewire, replace any wiring thats not good and replace any bad connections, as you have a Mikuni carbie I think you put the choke on and kick without any throttle, I am no expert on Mikuni carbies, but there is a nack of kicking these bikes but once sorted it should be a one or two kick to start.
This is one of the reasonds I love my Joe Hunt maggie no need to rely on a battery or electrics for running and always a one kick to start.

Ashley

Supercat said:

Yeah, just a single Mikuni carb with lever

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Try it with both taps open. 'Main' and 'reserve' taps can get swapped over, so I suggest find out which is which if you don't know for sure.

As it's a Mikuni (VM?) try to keep the throttle closed or very nearly closed, when starting from cold with the enrichening lever 'down'.
If it doesn't start after a few kicks it can then be too rich, so move the lever up and try again, if it starts you may have to push the lever down again quickly to keep it running until the engine has warmed up sufficiently to run with the enrichener off.

Thanks Ashman and L.A.B.

Yeah, if I'm lucky enough to get her to run I won't go far. Even a raz around the driveway or my street would keep me happy for a while. My goal is definitely to get the wiring sorted properly. I'll try the methods for finding the short suggested by a couple of others over the past day or two a try too.

And those starting tips sound great also. I'll try with both taps open, and with those lever ideas, and see what happens. Thanks!

After a bunch of kicks I'm noticing that the plug on the left cylinder is consistently very wet, but the one on the right is consistently very dry. Is this part of my problem?

Sounds like one cylinder is getting more fuel than the other or one cylinder is not firering at all, have you checked the wiring on the pick up to make sure it hasn't broken.

Ashley