If you would be so kind, I could use some more help please.

So I was so encouraged how well the old girl ran after a 20+ year hibernation that I checked into the brakes of my 1975 MKIII.

Well, they didn't fare as well. I put 2 new (13mm) master cylinders, all new stainless hoses, a VERY thorough cleaning of both calipers and new stainless pistons etc etc and they work great! At least on the centerstand.


I decided to replace the right handlebar switches along with the master cylinder because the head / pilot switch had been broken off. While I was at it, I replaced the headlight shell as there was a little rust pitting.

After all this, I turned the key on and all seemed to be as before, electrically speaking. I briefly touched the starter switch to check, and had positive results, but didn't have time to run it.


Today, I turned the gas on, tickled the carbs, and it fired immediately like usual, but died almost as fast.

Long story short, it consistently runs literally for about a second, then dies. I exhausted fuel related problems, and am convinced it is electrical. It acts just like old Chrysler products did when the ballast resistor went bad.

Here's what I'm wondering about:

When I replaced the handlebar switches, the new (? Chinese) switch harness had only 3 wires with individual male bullet connectors while my old one had 4 wires and a more modern 4 contact connector. The colors matched up, except there wasn't a grey wire in the new switch harness. At the time, I looked at the schematic and thought it must not be needed, so I terminated the grey wire and matched up the other 3.

Could I have bypassed the ballast resistor?

Has this different wiring with a new handlebar unit from Andover been experienced by anyone else here?

Thanks in advance for any thoughts you might have!

Randy

I suggest that you get your multimeter reved up and figure out what the wires from the new switchgear are connect to and how they behave when the buttons are pushed. Some switch makers don't supply a ground wire figuring that the handlebars are good enough; I sure don't.

The first circuit I wire, or check, is the earth/ground path. I do this to ensure that all appliances that draw power have an appropriate gauge wire to complete the current path without relying on the frame, corroded plug connectors, various rusty fasteners, the steering head bearings, yada yada.

Know thy switch wires...

Best.

2manytoys said:

Long story short, it consistently runs literally for about a second, then dies. I exhausted fuel related problems, and am convinced it is electrical. It acts just like old Chrysler products did when the ballast resistor went bad.

Click to expand...

If you're running stock ignition with ballast in place, then the same scenario could be happening. The starter relay bypasses the ballast while the button is pressed.

2manytoys said:

I exhausted fuel related problems, and am convinced it is electrical.

Click to expand...

2manytoys said:

Today, I turned the gas on, tickled the carbs, and it fired immediately like usual, but died almost as fast.

Long story short, it consistently runs literally for about a second, then dies.
Randy

Click to expand...

Your description sounds like fuel starvation.
Can you offer some insight into the steps you took after 20 years of sitting to insure the performance of the fuel delivery/carburetor?

2manytoys said:

When I replaced the handlebar switches, the new (? Chinese) switch harness had only 3 wires with individual male bullet connectors while my old one had 4 wires and a more modern 4 contact connector.

Click to expand...

But the original RH switch cluster has 5 wires: W, WY, WR, UY and U. 6 if it also has the grey wire (not shown on the wiring diagram).

2manytoys said:

Could I have bypassed the ballast resistor?

Click to expand...

If the (original points?) ignition is only being fed by the starter operating circuit then that could result in the ignition continually cutting out when the starter button is released which you describe.

RoadScholar said:

I suggest that you get your multimeter reved up and figure out what the wires from the new switchgear are connect to and how they behave when the buttons are pushed. Some switch makers don't supply a ground wire figuring that the handlebars are good enough; I sure don't.

Click to expand...

There isn't (or shouldn't be) a 'ground' wire (or connection to ground) in the switch cluster.
Edit:
It would also have been useful to know which "Chinese AN switch" it is.

Presumably Sparx but that has 5 wires.

Exact same thing happened to me on a a Mk3 I had. Then I noticed the kill switch was on. That's what to look into.

Assuming standard wiring, still positive ground, and points ignition, there should be a White/Purple wire from the ballast resistor to the coils. The other side of the ballast resistor should have a White/Yellow wire.

Disconnect that White/Yellow write and connect a White wire to the ballast resistor (a temp jumper to any white wire is fine). That eliminates any handlebar controls and especially the kill switch. Try it. If it still shuts off using the electric start, see if it fires using the kickstart and report back; or, feel free to call me and I'll walk you though figuring it out. 703-200-4025.

Lineslinger said:

Your description sounds like fuel starvation.
Can you offer some insight into the steps you took after 20 years of sitting to insure the performance of the fuel delivery/carburetor?

Click to expand...

I replaced the fuel tank, petcocks, tubing with new. Removed carbs, disassembles, soaked overnight in Berryman's, re-assembled with overhaul kit after blowing out jets with compressed air. It ran great until I replaced the handlebar switch.

L.A.B. said:

But the original RH switch cluster has 5 wires: W, WY, WR, UY and U. 6 if it also has the grey wire (not shown on the wiring diagram).



If the (original points?) ignition is only being fed by the starter operating circuit then that could result in the ignition continually cutting out when the starter button is released which you describe.



There isn't (or shouldn't be) a 'ground' wire (or connection to ground) in the switch cluster.
Edit:
It would also have been useful to know which "Chinese AN switch" it is.

Presumably Sparx but that has 5 wires.

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Click to expand...

The replacement RH handlebar switch is from Andover https://andover-norton.co.uk/en/shop-details/22800/switch-r-h-es-60-7328-06-5929- I now see in this picture they are showing 5 wires from the switch, my new one only has 3; blue/red, blue/white, and blue/yellow. My old original switch has these same three color wires and a solid grey one. The solid grey one is now disconnected.

The bike is original with points & condenser.

2manytoys said:

The replacement RH handlebar switch is from Andover https://andover-norton.co.uk/en/shop-details/22800/switch-r-h-es-60-7328-06-5929- I now see in this picture they are showing 5 wires from the switch, my new one only has 3; blue/red, blue/white, and blue/yellow.

Click to expand...

The three switches need a minimum of five wires (six with grey).

Blue/red (low/dip beam), blue/white (main/high beam) are left-hand cluster only switch wires.
RH and LH would both have a blue/yellow.

2manytoys said:

My old original switch has these same three color wires and a solid grey one. The solid grey one is now disconnected.

Click to expand...

That seems to make no sense as it would mean there were no kill switch wires (white W, and white/yellow WY) and no electric start button wires (either shared white W, or grey and white/red WR).
Only blue/yellow UY, would be a correct RH switch cluster colour wire.

L.A.B. said:

The three switches need a minimum of five wires (six with grey).

Blue/red (low/dip beam), blue/white (main/high beam) are left-hand cluster only switch wires.
RH and LH would both have a blue/yellow.



That seems to make no sense as it would mean there were no kill switch wires (white W, and white/yellow WY) and no electric start button wires (either shared white W, or grey and white/red WR).
Only blue/yellow UY, would be a correct RH switch cluster colour wire.

Click to expand...

I've only wired one MKIII so this might be all wrong...

Sounds like a late Triumph T150V RH control. Some used grey for the front brake switch. If so, there should be Blue, Blue/White, Blue/Red, and Gray. There should also be White and Purple/Black (or Brown/Black) and neither button would do anything without the white. That puts the kill button on the LH along with the turn signals and extra wire (White/Red, start). I'm wondering if the horn was moved the the other side and used the White/Red.

Also, Triumph called it Slate rather than gray (I think) and they incorrectly marked the wiring diagram the standard Brown for the stop light switch. I just finished wiring one with the gray instead of the brown in the handlebar console harness and I'm confident that it is original.

marshg246 said:

Sounds like a late Triumph T150V RH control.

Click to expand...

It's a RH Mk3 switch cluster:

2manytoys said:

The replacement RH handlebar switch is from Andover https://andover-norton.co.uk/en/shop-details/22800/switch-r-h-es-60-7328-06-5929- I now see in this picture they are showing 5 wires from the switch, my new one only has 3; blue/red, blue/white, and blue/yellow. My old original switch has these same three color wires and a solid grey one. The solid grey one is now disconnected.

Click to expand...

(Edit: The blue/white wire in the pic. should be blue!)

It would be nice to see pictures of what you actually have - the console(s) and the wires. Also, if you did the simple test I said before we could cut out a lot of guesswork about your original problem.

Thanks so much for the suggestions, the bike is in my shop which is not located at home so some days I don't make it out there. Will try to get pictures later today or tomorrow.

Again, thanks so much!!!!