Mine starts and runs a few minutes until it gets up to running temp and then starts to smoke from both pipes as well.
Although it having set for several years, after rebuilding the carbs before starting it, I poured automatic trans fluid into the cylinders, let it set a couple of days, then added more before finally turning it over with the plugs out. It shot the ATF out both sides but I figure sent some out of the exhaust valve as well. When I finally fired it up, it of course smoked like hell for a bit but then cleared up.
I figured that this smoking once warmed up now was just some of the ATF that had soaked into the baffles vaporizing once the mufflers get hot. Thing is, I drove it past that point till it quit smoking again a couple of times thinking that should have been the end of it. Well, it is still doing it.
I am now beginning to wonder if there is something else wrong.
"Theoretically what we really need here is a neutron flux high enough to bypass the gaps of instability."