Welcome fireW, " The red knob will be hot start, as these 4 strokes are a pig to start wen hot, watch MX gp "s if the fall off , they kick the hell out of em, hot start is excess fuel , thats why it offered wen you used it, Your problem is deffo carb jets " you say u cleaned it ? with a scoot of carb clean ? or did you check all jets, esp , pilot , and choke jet / well. the well is a long passage in the float bowl , the choke feed/ jet [ brass pipe] dips in to this well , thers a little hole at bottom of well into main float bowl , blast that till cleaner comes thru" take out pilot, [ flat screw driver] clean side holes and centre hole ,[with needle] then hold it up and blast cleaner thru, the main is the bg jet , .clean also. then needle , under the float, as this is where fuel enters carb ,, if u clean all these, i guarantee she"l start,, oh mind the pet cock,