Bad plug

rcleone

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I have 2004 21 horsepower Craftsman V twin lawn tractor. The other day I started it up and ran it to mow the lawn, it didn't sound right so I stopped, remover the spark plug and it was fouled. My question is will it leave any crap in the cylinder or valves. I got new plugs and started it up, it sounded a little funny , but then started to clear itself. I haven't used it since, so I'm wondering will it it get better the more I use it?
 

ESully

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Is the plug fouled from running rich, or oil fouled? If you can, post a photo of the plugs.
I have a Craftsman Lawn Tractor 21 Hp, 42" Mower Model No. 917.271851. Mine currently had an issue with a fouled plug from burning oil. I will be taking it apart this winter to see what shape the internals are in. I'm expecting it to need at least a honing and new rings.
 

rcleone

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I'm sorry but I threw the plugs away. But I can tell you that it was not burning any oil at all. I really hate to admit this, put the plugs are 12 years old. It has 294 hours on it. The model number is 917.274041
 

ESully

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It may be that the plug was worn and the gap was no longer correct. Can't really tell much without the plug.
Will it run better the more you use it? Maybe. If a bit of carbon built up with the fouled plug, it may clear up as you run it and the carbon burns off. If it fouled due to a carburetor issue, then the new plug may carbon up also. You'll have to run it a bit and then check the new plugs to see how they look.
 

slomo

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12+ year old mower. Pull the heads. Decarbon the cylinders, heads and valves. All in your engine manual as a "to-do" engine maintenance item. Neglect this and you are asking for future engine damage. As in scored piston bores ect.....

Must be a good running engine to have plugs that old.

Also need to clean the engine bock and cooling fins. These are air cooled engines. Do I need to explain more? Again another maintenance item to be done YEARLY or more often if required.

 
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