jetting ?

[atc110]

I have a 1985 ATC110. I think it's all original, and it is fouling plugs like crazy. Would I need a different jet, or a rebuild. My dad has had it worked on in the past, so maybe one of the idiots that worked on it screwed the carb up. For as long as I can remember, the plugs have been black. Also, it's impossible to start. I usually have to try 2 or 3 plugs. I put the choke on, pump it once, and it starts sometimes. If it doesn't I take the plug out and it's black and just soaked. Any help would be greatly appreciated.
thanks
atc110

[Quickonstep]

it could be one of anything or a combination of a couple of things.. leading causes of a fouled plug are crank case leak, blowby, dirty air filter, low compression. do a compression test, it should be around 100 or so psi (i dont know 110% for sure for that bike, but thats a good all around average) if thats not it, then you may need to check for a weak spark. Check your air filter also.

Jesse