1970 DT1C smoking bad spitting oil on startup after sitting a few months

Easy fix. Ride it.

Oil's getting past the check valve on the autolube pump and filling the crankcase. Running it will clear it out. Or, the right side crankcase seal is allowing transmission oil into the crankcase. If that's the case, replace that oil seal.

Ride it for 20 minutes if still smoking change the right crankshaft seal.

a

Thank you 

If there's as much oil in the pipe as it sounds from what you describe, it'll smoke for a very long ride at speed to dry it out. This smoke doesn't relate to motor condition so don't worry if it sounds & feels good.

Ok thank you seems to be burning transmission oil. Might have to replace a seal hopefully don’t have to split case 

Sorry to be a pain but what makes you say 'that'--trans oil. I'm all for leaving well alone, but if it's dissapearing then ok. Robust seals on 250's & 360's. Likely mine is still on original. Keep oil in the autolube tank though if it's drained into the motor over time. Crank seal isn't too difficult but clutch will need to come off as the crank gear won't clear the basket.