I have got an os 70 ultimate that smokes a lot when you pull the throttle to idle and make a left turn and decent i was thincking it could be the mixture but i wanted advice first because the engine transitions smoothley.

Smoking at low throttle/high manifold vacuum is quite common with model four-strokes. I notice mine all do that to a greater or lesser degree - especially OS Surpasses with their oil recycling crankcase venting mechanism.

If the Ultimate is running well otherwise, I'd just leave it and enjoy the smoke show.

Those Ultimates are very troubblesome engines and was discontinued because of that, if you have one that runs ok I`d leave it alone

I agree with asmund. If it ain't broke, don't fix it. That goes double for the 70 Ultimate.
Paul