My son got an 03 EC250 and it ran great at first (month ago). It started running rich and fouling plugs. I checked the jetting (seemed to be right in the middle what everyone else is running on the sticky, cleaned the holes, checked the enrichment (seemed to close off). It is very intermitent. It will run fine for a while then foul a plug and start loading up. Its getting worse, and now it will start great, nice and crisp for a few seconds, then load up when you give it gas. It will spit and spudder, and I even caught it making a sucking sound from the pipe and then shot out a puff of black smoke (but didn't die). I can ride it and it will start doing better and finally clean up and do fine. My son rode it Sunday about 25 miles. It did fine. I then started it up to load it and it did terrible like above. It acts like its going to die out, spit and sputter and suck. My next check will be the reeds, is the anything else I need to check while I am around there? Crank seals? Other ideas?