Help - engine running on

[odthing]

Hi,

what causes engines to run on after cutting the ignition? My pre unit Triumph is doing this. I have tried changing the timing, even quite radically, to no effect. The spark plugs are the right sort of colour, pale brown electrodes, suggesting that the mixture is about right.

[henry_norton]

I had run on problems a few years ago because I was running plugs that were too hot. The ignition was off but there was still enough heat on the tips of the plugs to ignite the mixture when it compressed. Changing them for cooler ones solved the problem straight off.

[L.A.B.]

what causes engines to run on after cutting the ignition?

Either wrong plugs as mentioned, or a build-up of carbon in the combustion chamber?

Time for a decoke maybe?

[odthing]

Thanks for the replies, Will