G'day guys, i'm looking for a bit of input from more experienced honda wrenchers, for my latest project. A 1985 Honda XL250R RFVC dual carb setup. The problem is the bike won't hold a steady idle, will hang up with a raised idle after accelerating/cruising. Is hard to start. And generally runs very rich. The bike has no air box, just a couple of pod filters. The carb seems to have multiple air leaks (tested for by spraying directed squirts of lithium grease), from the plastic caps above the slides, and from the air cut diaphragm plate area. I've done my best to seal the leaks to no avail. I've removed the air cut diaphragm and blanked it off to try stop it leaking vacuum as it was perforated. Currently the carbs both have 110 jets, and a 35 pilot jet in an effort to lean it out at idle. The rich mixture is apparent from the spark plug and the black smoke the exhaust produces. I've redone the valve clearances, reset the spark plug lead in the cap - makes a fairly healthy blue spark. Carbs are spotless inside. Bike sounds like it's 8 stroking at idle. Any help would be greatly appreciated, i think it needs new carbs and i'm ready to burn this thing.