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Banjo

1972 Commando 800 will not shut off sometimes

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Banjo

Like an old car that is hot and will not shut off when you turn off the key, my Commando does that. Acts like it is going to stop the engine but then it comes back to life just before it shuts off and repeats that cycle a few times before the engine actually does shut off.

Thoughts?

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TT

Have you removed the head and de-carbonized lately? (this is to be done every 500 hours of operation)

You might have some "hot spots" in the combustion chamber that keep igniting the fuel - even without spark at the plug. :whistle:

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Banjo

Have you removed the head and de-carbonized lately? (this is to be done every 500 hours of operation)

You might have some "hot spots" in the combustion chamber that keep igniting the fuel - even without spark at the plug. :whistle:

Engine was rebuilt about 20 years ago and never touched since and runs like a champ! Sounds like a good thing to look at. THANKS!

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linen beige

Have you removed the head and de-carbonized lately? (this is to be done every 500 hours of operation)

You might have some "hot spots" in the combustion chamber that keep igniting the fuel - even without spark at the plug. :whistle:

An old auto mechanics trick was to slowly pour a half cup of water into the air intake of the carb while the engine was running just above idle. :wtf: I'm sure some of you remember the water vapor injectors that were sold from the '30s to well up into the '80s. They are probably still available. In fact, some WW2 fighter planes had these injectors installed at the factory. :WRS: This water is vaporized in the combustion cycle. The carbon deposits in the cylinder absorbe the water vapor, soften, and are blown out the exhaust. I have sprayed water into an intake or two on some old car engines that "deiseled" and it did work. I have had a few small engines pull some water into their intakes when they were running as I hosed them off. A couple of these started running rough within an hour or so and inspection turned up carbon fouled plugs. More specifically, plugs fouled with a CHUNK of SOFT carbon. Cleaned off the gunk and they seemed to run a little smoother than they did before I got them wet. I can only surmise that they had a build up of carbon in their cylinders and the water loosened it up. Iwould not use more than a light mist from a spray bottle to lower the risk of cool water cracking something, but it just might break up your deposits and save you the cost of a head gasket. :D

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