Finally, the Bonneville lives!
Not sure if I posted the tale, but in the final sections of the National two weeks back the outfit re-developed it's missfire, had to be bumped at Leicester Forest East on the way home and finally died on the M-1. All this of course in torrential rain. Well I found the culprits:
1. Main Earth not connected to the engine except by a combination of corrosion and gravity.
2. A single rubbed through wire (starter button to relay) in the main loom.
3. A duff coil
The reason I'm chuffed? I found the lot
The main earth going makes a bike do really weird things. In this case, no lights except a constantly glowing indicator warning. Cross one indicator onto the other sides earth and you got flashing at half speed and dimly glowing oil and neutral lights
Test negative battery terminal to frame and you get 7 volts, across the battery 12, from positive to frame 6
The single duff wire simply means you can't turn it over on the starter unless you jump it onto the relay from the battery (easy to find) and the duff coil you only find by substitution once everything else is fine.
Now the RAC guy claimed the problem was a duff starter motor (close but no cigar, the main earth is next down that line) and the Haynes book of lies claims the starter should have zero continuity through the windings (so how does that work without lots of sparks?).
The morale of the story?
Be logical and test what you can test and even a muppet like me will get there. Connecting a battery straight across the starter and getting movement proves Mr. Haynes wrong.
Don't believe stuff Haynes never probably did and the RAC guy was guessing at. Test like Haynes say and you'd only find out the new motor turns out to the same as the old one.
Chances are with electrical stuff, it is the wiring not the components. I found both wiring faults by simple end to end testing and then visual inspection. It may take more time than putting components on, but it's a heck of a lot cheaper. I suspect a Triumph dealer would have fitted a new loom
Always know where the main earth is. A bikes frame can hold really different voltages
Andy
