Sounds like its overfueling at idle. The slow/intermediate jet may be a tad too big. Most exhaust mods lean an engine out so it has probably been jetted at some point. If it runs ok and only smokes when you goose it at idle, I'd leave it alone. You'll probably see some popping on decel but that's pretty normal unless it's extreme.It wasn’t running at all. Pulled carbs and cleaned and inspected. New enrichment valves and new cv boots? Don’t remember what they are called. We’re torn. New plugs new filter. Tried the seafoam. Tried mmo. Flushed coolant. Cleaned crankcase. Changed oil. Changed drive shaft oil. Replaced regulator. I suspect maybe the jets need to be replaced? It is stock except the resonator cut off the end of the pipes. I am a shade tree mechanic at best. I know enough to dangerous.
Runs and starts no problem. Just stutter occasionally and the black smoke issue. Cleans up when get going. If I juice it sitting I get the heavy puff.
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