non starter

Problem with 'er indoors’s cali. Nothing from starter button yesterday until I wiggled plug which goes into rear of headlamp. Got the bike home and had a look: Lots of fur and loose bullet connectors. Cleaned up, tightened up, wd40 etc but now nothing at all. Still suspect the wiring at this point and recall an issue with S3 where (original) stop switch on right handlebar wouldn’t let me start. Told to cut off 2 white wires behind headlight and join together, bike has worked fine since then on black/white wire and, I assume, some earthing somewhere. Decided to fit a seperate start button which, in any case, Cheryl will find easier to operate. Assume that one wire from button goes to b/w wire and other goes to earth (behind front brake light switch per standard), also wire the 2 whites together. It aint working!!! what have I missed!!! help please!

the black and white wire goes to the starter relay (number 85 ) one of the two white wires goes to the ingition switch ( number 50) and the other white goes to anyone of the two coils, there then should be a piggy back white wire from the coil to the other coil, if for example the cut-out switch (r/h handlebar) is not working and you want to bypass it you do as you have done, connect the two white wires together, as the ‘wiggling’ of the 15 pin plug behind the headlight did get the bike to start I would take a good look at the male and female 15 pin plugs, the b/w wire is easy to check as it should be in the top row next to the white, make sure the male and female pins are not loose,my 1978 850T3 starter switch wires went into a 3 pin mole connector in the headlight shell, just the 2 white and the 1 b/w wires but later models ( my old Spada for a start) had four wires, the 4th wire was a black earth wire,are the two wires on your new starter button the same colour? if not try switching them around.

northwest2012-07-31 21:16:09

The black and white wire from the stater relay terminal 30 goes up to the starter switch, the switch just earths the wire out. You can test this out by toucing the wire onto some metal on the bike somewhere. If the rest of the circuit is working, it should turn over. The wiring to the kill switch is separate (electrically)

Thanks chaps! I think break must be in the 15 pin connection as I struck gold when I jury-rigged my new switch direct to relay and down to frame earth. Rather than sod about with connection at h/light, I think I’ll whip orf the tank and direct wire (…or I could mount switch on/in pannier…that’ll fool 'em!). If 2 white wires are still good, I may even get a kill switch!

New 15 pin connectors are available BUT often pulling them out a clean then a line of silicone on the inside edge and pop it back I actually drilled 2 holes and put some garden wire around it to hold it tight.I had a period when the 15 way caused all sorts of silly problems for a couple of months 'till I did this not had a problem since.It IS a fail point and back in '76 maybe it was the best they could get BUT on later bikes there are much better options.