Spark plug

[Ralph]

Does anyone know why my sparkplug gets real black after running for a little bit? I tried to start my Honda 4 wheeler and it would not start so I put a brand new spark plug in and it started right up.. After runnning for 5-6 minutes I took the spark plug out and the brand new plug was very very black. What causes this?

[nitekrawler]

Carb maybe. Clean the carb out with carb spray, then clean the air filter. If that doesn't fix it, then try looking at the jets or the needle maybe bent.

Good luck

[JoeSuzuki]

Your runnin rich, too rich. Like said above, try to see why your gettin too much gas in your mix, or too little air. Try runnin it without the filter, or get a new filter.

[Ralph]

Thanks guys, I will try this.

[factoryfat]

Is it wet and black or dry/flaky and black?

[TRIKE]

Need to determine as the previous have stated.See if the plug smells like gas,which is possibly a carb issue or if its wet oily looking it could be oil. As well as maybe being a carb issue ,im assuming this is a 4 stroke?? If it is it could also be in that case a valve isue.Timing or just wore out valve seats. If its a 2 stroke I would lean towards the carb being the issue. Since you didnt say what cycle the motor was gonna be vague information. Good luck.

[YAMAHA_Jim]

Also check your air screw setting. Most are between 2 and 3 1/2 turns out. More than likely your problem is a simple adjustment.

[TimSr]

If you put it in a cold machine, and only ran it 5 or 6 minutes, and its black, that may be perfectly normal since thats barely enough time to get it warmed up to operating temperature. Cold motors run very rich until they get up to temp. You didnt mention where you are located, but if you are in a real winter climate, make sure you get the bike completely warmed up and revved out a little bit before shutting down. You will foul a lot of plugs if you frequently start it, run it a couple minutes and shut it back off before its hot in winter temperatures. Ive found this to be even more of a problem on 4 strokes. Alos, use great caution in jetting down a bike for fouling plugs in winter, because while they run very rich while they are cold, they will run a lot leaner than normal after they reach operating temperature.