OK, this cloud of smoke on startup has got to go, how do I fix it?

[Don-lo]

If the choke is making a huge difference, then it sounds like a fuel problem. You're not fouling out plugs? Can you turn off the choke earlier?

[donimo]

The electrodes of the spark plug are a bit lean if anything, the ring around it is black...

It does it as soon as I put the choke on, but goes away after 1-2 min, it IS oily, at least at first...

started with choke all day, just the tiniest whiff of blue smoke, but there is some small amount in the rear views after I pull away after sitting a few hours.

what would be wrong?

[Coady]

My 1979 GS750 has exactly the same problem.

My understanding is that using the choke creates more vacumm than usual, as the engine's reving higher without the carburetters opening. Therefor more oil gets sucked down the valve stems.

I find its also temperature related (colder = more blue smoke), but then when its colder I also need more choke. I also get blue smoke after long decel.