Photo of 1976 T140V gas tank

[Lordmac]

Because @gtm.76triumph posted last Tuesday (post #10).

Roger that Rudie. I'll eventually get the hang of it.

 

[Lordmac]

yes, I posted it last week. My tank is original, has never been painted!
Last week I put a new battery in and flushed out the tank. It started the day before, but now seems to have an electrical issue, no fire!
Back to troubleshooting.

How old are your condensers/capacitors? Did smoke escape from your wiring? If so, put some back in.

 

[gtm.76triumph]

That's funny!
I will be checking all the wiring and components.

 

[Rudie]

Last week I put a new battery in
It started the day before, but now seems to have an electrical issue, no fire!

I will be checking all the wiring and components.

A new battery is not necessarily a 'good' battery. Have you tried refitting the old battery to see if it makes any difference to the starting?

Then is it only that the engine will not fire; e.g. do the lights still work? If they do, not much point checking their "wiring and components"? Otoh, if electrics other than the ignition also do not work, could point to a fault in a component common to both circuits.

If you require help, it would help to know:-

. your electrical expertise;

. whether the bike has points or electronic ignition; if the latter, make and model?

 

[gtm.76triumph]

When I first put the new battery in and a shot of starting fluid, the bike stated up and ran.
Then it would start and die, without starting fluid. I found junk in the gas tank.
So I removed the tank and flushed it out. Reinstalled the tank, added fresh gas and tried to start the bike. Nothing...
Not even a pop with starting fluid!
The lights do work.
The bike has an electronic ignition (Boyer).

 

[gtm.76triumph]

 

[Rudie]

View attachment 53900

The Red wire at the bottom of your photo above, does it connect to a harness Brown/Blue wire out of shot, or has the bike been converted to 'negative ground' using the original harness? Reason I ask is the electrics would originally have been 'positive ground', the original harness included numerous Red wires from electrical components originally connected to the battery positive terminal.

Do you have a Voltmeter or multi-meter? If not, beg, steal or borrow one or buy a multi-meter. If you buy, obtain a cast iron signed in blood guarantee it has both good calibration and e.m.i. (electro-magnetic interference) protection - without good calibration, the displayed measurements are unreliable for fault diagnosis; without e.m.i. protection, the meter will not give reliable measurements near a running engine.

If/once you have a meter, if a multi-meter, set it to the Volts scale just above 12V, connect one meter lead to each battery terminal:-

. all switches off, meter should display at least 12.6 Volts;

. ignition only turned on but engine not started, ideally the meter display should not change but, if it does, it should not reduce by more than 0.1V;

. all switches on, engine still not started, again ideally the meter display should not change but, if it does, again it should not reduce by more than another 0.1V.

Reason the meter reading should not reduce by more than 0.1V at each stage above is 12.6V indicates a fully-charged battery while 12.3V indicates a half-discharged battery (one reason for "good calibration" above); a 'good' battery should not go from indicating fully-charged to half-discharged just turning on ignition and lights.

Please post what you find.

 

[gtm.76triumph]

 

[gtm.76triumph]

yes, the red wire at the bottom does go to a brown/blue wire.
Voltage is good, and less than 0.1V change with key on.

 

[Rudie]

Voltage is good, and less than 0.1V change with key on.
red wire at the bottom does go to a brown/blue wire.

The electrics are still standard 'positive ground'.

Boyer e.i., I would connect the "Transistor Box":-

. Red wire directly to the battery +ve terminal, not as shown in any Boyer wiring diagram.

. Black wire to one coil -ve terminal. "Link wire" between that coil's +ve terminal and the other coil's -ve terminal. Only this second coil's +ve terminal connected either directly to the battery +ve terminal or at least to a harness Red wire. If connected to a harness Red wire, you should be able to measure 'full continuity' - almost zero Ohms on your meter - between this connection and the battery +ve terminal. Again, second coil +ve not connected as shown in any Boyer wiring diagram.

. Is the handlebar kill switch still connected/used?:-

.. If it is, Transistor Box White wire to one harness White/Yellow wire - W/Y is from the kill switch; original points, there were originally two W/Y ends by the coils, one connected to each coil -ve terminal; Boyer, Transistor Box White is connected to one W/Y, the other should be insulated securely.

.. If it is not, Transistor Box White wire to a harness (plain) White wire, you should be able to measure full continuity between this connection and the White wire terminal on the ignition switch.

I also ensure there is a harness Red wire connected to one of the bolts or studs through the cylinder head and I can measure full continuity between this connection and battery +ve.

Aside, when you have sorted the ignition problem, if you have not already fused the Transistor Box White wire, consider fitting a 5A or 7.5A blade fuse and holder where it is connected to the harness. Reason is the standard fuse in the harness near one of the battery terminals (originally near the -ve terminal) is (should be) in the 15A-20A range so is rated too high to protect any e.i. if something fails closed just in the ignition circuit - you might have noticed the Boyer fitting instructions say current through the Transistor Box should not exceed 5A continuous?

Boyer Transistor Box connected as above, unscrew at least one of the spark plugs from the head, reconnect the plug to its cap, lay the plug on the head ensuring the plug has a good 'ground' to the head, turn the ignition switch on and off; each time you turn the switch off, the plug should spark; if it does not, first move the plug around to ensure it definitely has a good 'ground' to an engine component before suspecting something else is not working.

 

[gtm.76triumph]

Thanks for the help.
I will try this tomorrow. Taking my wife to the doctors today.
I'll let you know the outcome.

 

[gtm.76triumph]

 

[gtm.76triumph]

Rudie, I made the changes one by one. See wiring.1
Not able to start. No pop at all...

Made the last change, white wire from transistor box to wiring harness was on a white wire in the harness. I changed it to the white/yellow wire. See wiring.2
Still not able to start. No pop at all...

I did pull one spark plug at a time, grounded to the engine head, and turned the key on and off, had a spark on each one.

I think I'm going to flush out the tank again, and drop the bowls on each carburetor and clean them completely!

Your thought???

 

[Rudie]

made the changes one by one.
I did pull one spark plug at a time, grounded to the engine head, and turned the key on and off, had a spark on each one.
Not able to start. No pop at all...

Boyer Transistor Box connected as above, unscrew at least one of the spark plugs from the head, reconnect the plug to its cap, lay the plug on the head ensuring the plug has a good 'ground' to the head, turn the ignition switch on and off; each time you turn the switch off, the plug should spark

Next test was/is to check the plug sparks when the engine is turned over.

If you do not see the plug spark when you kick the engine over, the Transistor Box is not receiving trigger signals from the Boyer "Stator" (where the points and auto advance unit used to be in the engine timing cover). The fault/s could be one or more of the following:-

. the Boyer "Rotor" is not turning with the camshaft;

. the Boyer Rotor has slipped out of position (note the warning in the Boyer fitting instructions that the supplied rotor securing bolt might be too long).

. If the Rotor is in the correct position, measure the resistance across the Boyer Stator and the resistance of the wires connecting the Stator to the Transistor Box. Your meter:-

.. Is it fitted with a known good battery?

.. When you use it to measure Ohms, does it: zero automatically when you hold the lead ends together; or does it have a thumbwheel to zero it when you hold the lead ends together; or do you have to hold the lead ends together, note the meter reading, subtract it from subsequent readings?

. Once your meter is either zeroed or you know the figure to subtract:-

.. unplug the two Boyer Stator wires, insert one meter lead end in each Stator wire socket, your meter should display 137 Ohms (corrected if necessary) or very close to it; wiggle the Stator wires around while ensuring the meter display does not change (change would indicate a partially broken wire or other contact fault);

.. if the meter does display 137 Ohms or very close to it without any changes, reconnect the wires from the Transistor Box to the corresponding Stator wires, unplug the same wires from the Transistor Box, repeat the same test above, one meter lead end in/on each wire from the Stator; the reading should be the same 137 Ohms or very close to it to indicate the wires between Stator and Transistor Box do not have any measurable resistance.

going to flush out the tank again, and drop the bowls on each carburetor and clean them completely

More simply, unscrew each float bowl drain in turn, hold something underneath the bowl to catch liquid, open each fuel tap in turn, allow fuel to run out of the bowl for one minute, thirty, twenty, fifteen or ten seconds (the longer the better), turn off the tap, measure the fuel that has run out and equate it to 300 millilitres/10 US fluid ounces per minute.

Unless fuel is flowing at significantly less than 300 ml/10 oz per minute, you know there is no need to flush out the tank, unlikely to be any need to dismantle the carbs unless to check the pilot jets are not blocked (it would be surprising if both had blocked up overnight).

 

[gtm.76triumph]

I will try these items tomorrow, Sunday afternoon.

 

[gtm.76triumph]

Hi Rudie, I'm going to work through the list this afternoon.
I didn't see spark on the plug when the engine turns over. I need to refresh my understanding of how to set the timing.

 

[gtm.76triumph]

 

[gtm.76triumph]

The timing marks look spot on!
Still no spark at the plug when turning over the engine.
Not sure about the resistance readings:
At the stator with wires unplugged, RX1 = 0, RX10 = 12
With the wires plugged back in at stator and unplugged at the Transistor box, Rx1 = 0, RX10 = 38

 

[Rudie]

View attachment 54024

Why is there a disconnected Black/White wire?

Please post a photo of the entire Boyer Stator.

Not sure about the resistance readings

"RX1" = Resistance multiplied by 1, "RX10" = Resistance multiplied by 10. I.e. meter set to "Rx1" (note small "x" = "multiplied by"), the meter should display the previously posted, "137 Ohms (corrected if necessary) or very close to it".

 

[gtm.76triumph]