I just bought a AC 250 2x4 about a month ago, haven't even put a full tank of gas through it. I got on it the other day, and the thing wouldn't start. I changed the spark plug and it ran like new, better than new!! I was ecstatic to say the least. Well after about an hour of riding yesterday and my wife putting around the yard this morning, I went to start it this afternoon. It didn't crank right up like it has since the new plug, but ran OK. I pulled the plug out and sure enough, it's black as can be. I talked to a guy at the dealership over the phone, and he said I may not be turning the choke off all the way when riding. Well, that's the thing, I haven't even had to use the choke to start it, so i know I'm not leaving the choke on. Any ideas on what's fouling these plugs??

 

Two things, choke lever is off in the UP position and are you turning the fuel valve off when not running? You should have to use the choke to start a 250 when it is cold, even on a warm day.

 

I've got the lever in the UP position. Hmmmmmmmm, I haven't been turning the gas off when not riding. Didn't know that would foul the plug. You think that will cure the problem??

Thanks for input

 

It can foul the plugs and also give you hard starting if the needle and seat are a little weak and bleeds fuel into the intake system while the engine is off. You should always turn the fuel off when not running for overnight or longer periods of time with a gravity feed fuel system. I set the limit at and hour for turn off.