[Flicker]

So on these bikes, the kill switch only intermittently stops the 12v going to the coil? On my previous bikes, there's an on/off switch that sends/cuts off 12v to the coil so they don't get overcharged with the key on and engine off. Does this mean that with the key on the 3 or 4 position, 12v will always be going to the coils?
So pressing the button snould stop continuity between the W and W/Y?

Yep, and my measurements say if you have both breakers closed with engine stopped, you're eating 4 amps continuous. Design flaw.
It's one reason many of us have gone to electronic ignition or are very mindful of how long we leave the key on.

right hand switch stopped working and maybe he didn't feel like cleaning the contacts?

Yeah probably

So the lever is for turn signals and the bottom button is the kiill switch?

Yes. As Stuart said top button was future planning for electric start, both buttons on both sides are momentary

On mine, the contacts were corroded with age as well. I also had to do some repairs in there. Not bad for a 50 year old bike though and it works fine now

 

[StuartMac]

Hi,

The switch cluster has a lever in the middle, something that looks like a button on top but does not actually press in, and an intermittent button on the bottom. So the lever is for turn signals and the bottom button is the kiill switch?

Both buttons should move so "does not actually press in" might be another DPO 'modification'?

The two snags with this cluster are:-

. One button is press-to-make (the putative electric-start button, originally with White/Red wire), the other button - the kill button, originally with White/Yellow wire - is press-to-break. This is unlike the other cluster where both buttons (headlamp flash and horn) are press-to-make.

. The electric-start button is supplied by a White wire, all of which are 'hot' when the ignition switch is on. So, if the button's pressed, the White/Red wire is also 'hot'; if a PO wasn't too 'hot' with electrics, he might've thought the original snap connector insulating the White/Red wire's bullet terminal "didn't do anything" so could be removed ... the next time the button was pressed, the exposed bullet caused a short that stopped the bike ... the PO 'fixed' the first mistake by stopping the button moving ...?

the lever is for turn signals

Yes, as long as the switch cluster is standard '71-'74 (to '75 in the ROW) ... post a photo. of the other side of the switch cluster?

Left side handlebar switch (5 wires)

Uh-uh, there should be six or seven wires; reason I say "six or seven" is it depends how many White wires - electric-start button (White/Red wire) and kill button (White/Yellow wire) are both supplied by a plain White wire; if it's the same plain White wire, there are total six wires; if it's a different plain White wire each, there are total seven wires.

white and yellow/white = 12v

Press-to-break kill button.

All wires should be battery Volts (i.e. lead-acid-type battery = 12.6V) measured between any and the battery +ve terminal.

green and green/white = flasher warning light
light green - flasher unit

Mmmm ...

. Light Green/Brown (insulation mainly Light Green with one or two thin Brown tracer lines) is from ('positive ground' electrics) the flasher unit to the turn signals lever;

. Green/White is from the turn signals lever to the right-hand (timing side) turn signals;

. Green/Red is from the turn signals lever to the left-hand (drive side) turn signals.

The flasher warning lamp (amber, in the headlamp shell) is connected between the Green/White and Green/Red wires.

In reality, both handlebar switch clusters' wires connect to the corresponding wires in the main harness at a big handful of snap connectors under the fuel tank, headlamp (including the 'idiot lamps') and turn signals wires then run forward to the corresponding components. Either at that big handful of snap connectors or somewhere between them and the flasher warning lamp itself, the lamp's Green/White and Green/Red wires are connected to the corresponding turn signals wires.

on these bikes, the kill switch only intermittently stops the 12v going to the coil?

Yes, press the kill button, hold it pressed 'til the engine stops; the ignition circuit's 'hot' again as soon as the button's released.

my previous bikes, there's an on/off switch that sends/cuts off 12v to the coil

Not actually mandated in the US 'til the FMVSS effective 1st January 1975. One of the reasons '75 Triumph twins weren't sold in the US was they still had the push-to-break, release-to-make kill button.

cuts off 12v to the coil so they don't get overcharged with the key on and engine off.

Old wives' tale. Any ignition coil intended to be switched by points draws between 3 and 4 Amps (defined by the coil's primary resistance) with the rated Volts across it. Fully-charged coil not discharged by points opening (or replacement EI switching off the primary), it just turns the Amps into heat; even 12.6V and 4 Amps is only about 50 Watts (for comparison, each heating element in an electric fire is at least a 1000 (thousand) Watts).

key on the 3 or 4 position, 12v will always be going to the coils?

Yes. But no biggie.

pressing the button snould stop continuity between the W and W/Y?

Yes. But, as I say, releasing the button immediately restores continuity between the W and W/Y.

PO installed an accessory horn switch on the left side handlebar so I'm assuming the button on the right hand switch stopped working and maybe he didn't feel like cleaning the contacts?

Possibly. Meter set to Ohms, one meter lead end on the Purple/Black wire, other meter lead end on the White wire supplying the button, meter should display high Ohms (no continuity); if pressing the button causes the meter display to drop to near-zero (continuity), the button works. Then could be the PO wanted to be able to hoot the horn and flash the headlamp at the same time, but didn't realise he could simply connect the wire from the unused 'electric-start' button?

switch to an electronics repair shop on Saturday. Apparently, someone named Emmet will be taking care of it

Maybe double-check he knows the kill button is the push-to-break one, not the push-to-make one?

Hth.

Regards,

 

[Stockton350]

It has been a while since posting an update, so here is where things are at with the 72 Triumph Bonneville:

• The carbs have been rebuilt and put back on the bike
• I cleaned up and repainted various covers, coil bracket, etc. It was all very rusty and now it's somewhat presentable.
• I managed to lose one of the ferrules for the throttle cable. It made me shake my head and wonder why they wouldn't have just designed cable stops as part of throttle body.
• The electronic's guy is ghosting me, so I haven't gotten that switch back. I may need to do it myself.
• The gaskets for the oil screen got lost in the mail, so I've been waiting for a couple weeks to get those and finish changing the oil (hopefully today).
• I'll also change the garbox oil -- Anyone know the capacity of gearbox oil? I understand that I'm supposed to be using the plug hole to see when the correct level has been reached, but it would be good to know a ballpark when I buy the oil.
• I'm cleaning out the tank with vinegar. There's lots of rust in there, but I don't see any holes. Both the switches seem to be missing from the petcocks. Trigger alert: Does anyone ever plug up the left side and only run a petcock on the main? Running out of gas is not an issue, so I don't really need reserve. I'm wondering if I can run a petcock on the right side only, link the two carbs via the connecting hose, plug the external hose on the left carb and plug the left petcock hole. Thoughts?
• Is this the correct part: 1/4 inch BSP Petcock Fuel Valve - Reserve - For Triumph BSA Norton

Thanks!

 

[StuartMac]

Hi,

Does anyone ever plug up the left side and only run a petcock on the main? Running out of gas is not an issue

this is my first British bike

So how would you know?

brought a bunch of old Japanese bikes back from the dead

They all had accurate fuel gauges, you never used reserve on any of them?

If they did all have accurate fuel gauges, note your first British bike doesn't have any fuel gauge, never mind "accurate" ...

correct part: 1/4 inch BSP Petcock Fuel Valve - Reserve - For Triumph BSA Norton

It's 'correct' insofar as it's the nearest copy you'll find of what Meriden fitted to your bike when it was built.

Don't like 'em myself, whichever side - right or left - has the Reserve tap, there'll be a time when Main runs out but the corresponding hand is doing something else important.

Very late on ('82?), Meriden started using handed Italian taps that both had Main and Reserve. They need an adaptor to fit the 1/4"BSP threads in your bike's tank but that's a Triumph part too. Post again if interested and I'll post details (part numbers, etc.).

Whether you choose Italian taps on adaptors or the tap you've linked above and the corresponding Main one, be aware each must have both sealing and plain steel washer illustrated/listed in the parts book between tap locknut and tank.

Hth.

Regards,