White smoke is coolant burning. If it has a slight blue tint then it's oil. My left pipe has always had a more smoke when it's cold but cures when it warms up.
As far a syncing the carbs, pull the air filter and look at the carb slides. Pull the throttle and make sure they go up at the exact same time. If not, and you have tors, adjust the screw on the tors (big box on top of the carb) until they leave at the same time. This is also your idle setting. If the idle is to high, adjust the slide that is to high. If the idle is to low, adjust the slide that's to low. If the idle is fine, you may need to meet in the middle.
I don't think sync is your problem unless they are way off. Make sure the pilot screws on the carbs (that's your jetting from 0 to 1/4 throttle postition) are the same. Adjust these by start at turn full turns from bottomed. If the there is hesitation when first hitting the throttle turn them in 1/4 turn at a time until it is worked out.
That's it for low rpm. When exactly are you seeing this smoke. You may have a head gasket leak. If so, don't worry, it's only $10 for a gasket and really easy to change. Could be something else to.
Please, be more specific about when you see the smoke.
Oh, and welcome to banshee hq. Most of are here to help. Just ignore the rest