Topic: Help locating short.

[pidaster]

I've got most of my K6 put back together and was going to start on carb tuning tonight. I put a little gas in the tank and started her up. I let it start warming up and turned the choke off. All lights are working at this point. The bike started to sputter a little and I looked at my clear fuel filter and realized I didn't have enough gas in there. I turned the ignition key off and just happened to be looking at the fuses to see the main 15A fuse blow. My brown, brown/white, and black wire all show ground when the ignition is turned on. I disconnected all the brown/white wired in the headlight bucket and disconnected the brown wire at the tail light. Still ground with ignition. I traced the black wire back to the voltage regulator. It shows ground unless I unplug it. The green and white wire both show ground all the time. Is the regulator stuck?
I get 37 ohms between green and white. 37 ohms between green and black. 0.5 ohms between white and black and constant continuity.
What say ye, wise ones?

[mystic_1]

The green wires is a ground so that's normal.

The white wire at the regulator is the Field Coil lead.  You should see about 7Ω resistance from that to ground.  If not, remove the sprocket cover and access the wires down there.  Disconnect the white and green wires and test the field coil from there.  If you see around 7Ω there, there's a short in the harness between the regulator and the field coil.  If you still see a short, your field coil maybe shorted out.

The regulator never actually grounds out the black wire, which is a good thing since that's your switched 12V supply.

mystic_1

[Spanner 1]

Your meter readings dont mean anything as all the 'hot' wires will read to ground unless everything on the bike is disconnected , points, coils etc. Anyway, don't think anything is 'wrong' except the fuse clips are tarnished/loose. Shine all the fuse clips and replace the 3 fuses with 15A main, 7A headlight, 5A tail-light. Look on the backside of the fuse block too for melted/ loose connection.... good luck 

[pidaster]

Fuse clips are nice and shiny so that's not the problem.
Sounds like Mystic is on to something. I'll check that out when I get home. Maybe it's just a pinched wire at the sprocket cover.

[cookindaddy]

About Spanner1's comment: you definitely will have meaningful resistance measurements on the hot leads to ground if you have an ohmmeter that reads accurately down to an ohm or so and a good set of test leads. You must zero the ohmmeter before the measurement by shorting the test leads and adjusting to zero to eliminate the resistance of your test leads and to compensate for the aging of the ohmmeter battery. Digital meters sometimes have this zero adjustment available internally. Otherwise your readings may all seem to be "short" with the meter going to zero.

I second his advice about checking the condition of the fuse holder carefully. Corrosion or poor contacts will cause heating and may melt the fuse. Melted or burned insulation on the back of the fuse holder will show you that this is happening. As well as being clean, they should also grip the fuse tightly for best contact. With the fuse out, you can bend the clips together slightly so that they grip the fuse better. Check that you are using the correct physical size fuses. The 3AG type common in North American are too long for the Honda fuse holder and don't make good contact with the clips. You should get the proper metric sized fuses from a Honda dealer - they are still available at reasonable cost.

I'd follow Mystic_1's advice.

Also, since you had it running without the fuse blowing for a time, you may have an intermittent short, for example, frayed insulation that allows wires to touch each other or the ground if, for example, you turn the front wheel with the handlebars. A careful inspection of the entire harness might be in order.

[pidaster]

Checked it out when I got home. Meter read at 7 ohms just as Mystic pointed out. Next I grabbed a new .22 caliber gun bore brush (bout the same size diameter as the fuses) and cleaned the fuse clips really good. They were already shiny but now they are really shiny. Well, guess that did the trick cause she works again.
Props and thanks goes to Spanner!

[Gaither]

Spanner's right!

Those fuse clips will fool you. May look a just a little dull but OK (like mine did). I began blowing the main 15 amp fuse repeatedly. Got about 3 miles on the last one.

I'll admit, in my ignorance, I didn't quite believe it would solve the problem when I was told to shine the clips. But, clean 'em I did. I also used a .22 cal. bore brush (perfect) to clean 'em. Folks on here really know their stuff.

NOW, I'm a believer! No more blown fuses! No way to argue with success and/or the experienced advice of folks who know what they're talking about.