Help. Triumph keeps stopping when hot.

My sons Harley had the same kind of fault . Turned out it was a faulty sensor .

This is the relevant section of the manual


Intermittent Ignition Problems
Intermittent problems are usually caused by temperature or vibration variances. Perform the following.
Temperature test
NOTE
Perform Steps 1-3 with the engine cold.
1. Remove the outer timing cover, inner timing cover and gasket as described in Chapter Twelve.
2. Start the engine.
38
3. Spray the sensor (Figure 38) with a refrigerant (avail- able at electronic supply stores). If the engine dies, replace the sensor as described in Chapter Twelve.
4. Allow the engine to warm to normal operating tempera- ture. Then apply heat to the sensor with a heat gun. If the en- gine dies, replace the sensor as described in Chapter Twelve. 5. Remove the ignition module cover from the left side of the motorcycle. With the engine running, apply heat to the ignition module (Figure 36) with a heat gun. If the engine dies, replace the module as described in Chapter Twelve. 6. Install the inner timing cover, gasket and outer timing cover as described in Chapter Twelve.

Good luck

Buy a Harley they always run hot

Agreed Mick,

Personally I would set it up with about 5mm Air gap then stand clear to observe the spark by cranking the engine. I would not run the risk of making my body part of the HV circuit by holding it in any way!

Much care needs to be taken when shorting plug cables if it has a CDI ignition system, as they can generate EXTREMELY HIGH voltages! Have a known good spark plug attached to the h t lead and hold that to ground with a Very Well insulated tool or preferably a piece of wood. Regards Mick C.

Sadly there isn't enough info to make a solid guess as to what is really going on...

But when an internal combustion engine won't run intermittently but the starter still turns the motor, there are usually two main categories of causes -

1 - No fuel reaching the cylinder due to fuels system issues.
2 - No ignition of the fuel mix due to ignition system issues.

Of the two the Ignition system is usually the easiest to diagnose - when the engine wont run remove the spark plug lead spark plug and using a conductor like a philips head screw driver carefully test for spark from the lead on the engine block. (don't make yourself part of the circuit unless you want to feel the "LUCAS effect" personally!!!) Good one Blydie LOL

If there is no strong spark when the engine is cycled - the ignition system has the problem and there is probably intermittent continuity effected by heat somewhere in the ignition circuit. The faulty cables will have to be repaired or replaced..If there is a Strong spark check that the spark plug looks ok then move on to the Fuel system.

EXTREME CAUTION NEEDS TO BE EXERCISED DUE TO THE RISK OF FIRE.

If it is a carby system - open the drain valve on the carby to test if the fuel is flowing from the tank well. this needs to be tested while the engine will run and while it wont so the results can be compared. Heat could have caused a vapour lock in the fuel line and no fuel flow when it gets hot, this starves the engine for fuel. If this appears to be happening try to replace and reroute the fuel line to a cooler location.

These are my best suggestions - so Good Luck

Very witty there Blydie!

It sounds Electical to me, have you checked for smoke?

ELECTRICAL THEORY BY JOSEPH LUCAS
Positive ground depends on proper circuit functioning, which is the transmission of negative ions by retention of the visible spectral manifestation known as "smoke".
Smoke is the thing that makes electrical circuits work. We know this to be true because every time one lets the smoke out of an electrical circuit, it stops working. This can be verified repeatedly through empirical testing.
For example, if one places a copper bar across the terminals of a battery, prodigious quantities of smoke are liberated and the battery shortly ceases to function. In addition, if one observes smoke escaping from an electrical component such as a Lucas voltage regulator, it will also be observed that the component no longer functions. The logic is elementary and inescapable!
The function of the wiring harness is to conduct the smoke from one device to another. When the wiring springs a leak and lets all the smoke out of the system, nothing works afterward.
Starter motors were considered unsuitable for British motorcycles for some time largely because they consumed large quantities of smoke, requiring very unsightly large wires.
It has been reported that Lucas electrical components are possibly more prone to electrical leakage than their Bosch, Japanese or American counterparts.
Experts point out that this is because Lucas is British, and all things British leak. British engines leak oil, British shock absorbers, hydraulic forks and disk brake systems leak fluid, British tires leak air and British Intelligence leaks national defense secrets.
Therefore, it follows that British electrical systems must leak smoke. Once again, the logic is clear and inescapable.
In conclusion, the basic concept of transmission of electrical energy in the form of smoke provides a logical explanation of the mysteries of electrical components especially British units manufactured by Joseph Lucas, Ltd.
And remember: �A gentleman does not motor about after dark.� - Joseph Lucas, �The Prince of Darkness� - 1842-1903
A few Lucas quips:
The Lucas motto: �Get home before dark.�
Lucas is the patent holder for the short circuit.
Lucas - Inventor of the first intermittent wiper.
Lucas - Inventor of the self-dimming headlamp.
The three-position Lucas switch--DIM, FLICKER and OFF. The other three switch settings--SMOKE, SMOLDER and IGNITE.
The Original Anti-Theft Device - Lucas Electrics.
If Lucas made guns, wars would not start.
Back in the �70s, Lucas decided to diversify its product line and began manufacturing vacuum cleaners. It was the only product they offered which did not suck.

Q: Why do the British drink warm beer? A: Because Lucas makes their refrigerators.
This has been referred to as the smoke theory. When the smoke comes out its finished, cooked or done for.

I would suggest that he takes the fuel tank filler cap off when he thinks it's about to stop.
Or, take it off when it stops and then try to start it again.
If it starts, then buy a new fuel tank cap.
Just a suggestion.

Eric has asked me to post this on the chance someone can offer some advice.

His Triumph Thunderbird 1997 3 cylinder will run for 10 mins untill nice and warm and then stop.

It will restart only after it cools down.

Good luck.

Danny.........................