Hitchcocks Forum

Hi all, the EFI is about to make its first trip of the new year... but first I have the last (!) of the electrical issues to sort out. I need to replace the earth connection from battery to frame but I wonder if anyone knows what gauge or rating of cable to use (there is no cable in place so nothing to copy)? Also, does anyone happen to know the size of bolt that is supposed to fix the earth cable to the frame behind the battery? You may recall that my bike appears to be missing it's original earth... If anyone has any tips on removing the right hand switch gear from the handlebar that would also be great - an occasional short in there methinks. Back to work on Monday and transport would be handy

Hi Michael,

I just measured my earth wire and over the insulation it is 4mm diameter, so the conductor is about 3mm dia. and of course multi strand, so I calculate the conductor is about 6mm2.

Where it is attached, I could not quite see, but somewhere near the starter solenoid I think.

Cheers TrevorCH

Hi Trevor. Thanks for the info. Out of interest, how many cables are attached to your negative battery terminal? I have two, one thin wire and one fat one, probably around 6mm in area connected to the starter motor casing at the other end. The starter is also connected via the solenoid to the positive battery terminal - might the negative one be my main earth?? Shouldn't it be connected to the frame and only one cable (positive) to starter since the starter should be grounded by means of its attachment to the engine?

Negative has two wires, one quite thin and the other as I described. The 6mm connection to the starter serves as the earth connection and the thinner negative goes to the frame also as an earth.

The red positive goes via the solenoid to the other side of the starter. There is a second red thinner positive wire that goes to a 20 amp fuse and feeds power to all the other elements except the starter motor.

I have the factory workshop manual, but it gives no information about the right hand switch module, except as part of the wiring diagram.

Cheers TrevorCH

Cheers Trevor. Very useful! Will check the routing if the thinner negative wire later on, and it sounds like the rest of my circuit is almost as it should be. The wiring diagram in the manual indicates the starter connected to frame earth, not the battery negative terminal which is what has thrown me. Will play with my dodgy switches when I get a chance too. Thanks for the help! Michael.

And the manual wiring diagram also shows three wires from battery!? The main earth, the lighting/staring/charging circuit and the ignition/ECU circuit. Oh well...

RH switch module is held together by two screws. The light 'flick' switch is held by a further screw and washer above and below, and the switchgear itself is held by two further screws. The throttle cable serves to make things awkward so it's best to remove it. Once out, all contacts can be cleaned up, waterproofed and then refitted. Seems to have done the job

Hope a lecky can reply to this, but i was told that thin wires can give a high resistance so always used " reasonable " size wiring when repairing or installing extras, dont like the thin stuff at all

Hi Neddy,

You are quite right, thin wires have a higher electrical resistance than thicker copper wires. Normal m/c wiring, as sold on this site, has a copper X section of 1mm2 and is rated to carry 16 amps continuously. The largest single electrical load on a Bullet, ignoring the starter motor, is the headlamp at 55 watts. From Ohms law, the current required is 55/12 = less than 5 amps. Apart from needing to be rated to carry a certain current, the wire and insulation need to be mechanically strong enough to resist normal loads and abrasion. The weakness usually lies in the connectors which is the first point that corrosion strikes. Mechanical compression joints are generally most reliable, but I prefer good soldering after which a good moisture resisting coating is applied. Nuff said? Cheers TrevorCH

-----------and there's more !! Other factors are in play-- such as the length of the wire, the "conductivity" of the material in question (or the LACK of it for resistance purposes), and the TEMPERATURE at which that wire is operating at..ie the HOTTER it gets, the more resistance it will offer---the COLDER it gets the LESS it will offer..And from this line of research we get }---- SUPERCONDUCTORS and the spin-off benefits that it brings.. Have a look at this }---- http://scienceblogs.com/principles/2010 ... ctors-work --------------- Don't worry, our friends such as ANDERS FR etc out in the colder climates won't be getting "Free" electricity just yet...but in theory it is now possible to have electric motors where the calculated torque output is greater than today's metallurgy could transmit !!-------IN THEORY, remember...