Excessive white smoke from 2-strokes

Oil smoke can only come from your gas/oil mixture. Make sure your mixture is correct. Over oiling will damage your engine.

if it is a 2 stroke , reduce the ration of oil to fuel at the oil pump meter jet
if it is a 4 stroke , go up a grade in the engine oil ( 15w 20 to 30w 50)
replace the rings

It is most likely oil. Probably passing past the rings on the piston. I use 2 stroke oil in all my mowers / small motors whether they are 2 stroke or 4 stroke (based on advice from a small motor repairer) since the 2 stroke oil helps lubricate the bore and even though there is some minimal smoke usually on start-up. Depending on how bad the smoke is you can try a heavier grade oil and I would recommend using a 25:1 2 stroke mix if you want to extend the life of your small motors.

It's a 2 stroke engine and was a real racing bike when it came out. A little smoke is normal for 2 stroke engines...have fun with that classic!

Is It A 2-Stroke Or A 4-Stroke. It Could Be A Fuel Mix Problem Or A Piston Ring Problem. 2-Stroke (Mix) 4-Stroke (Rings)

If its a 2 stroke, yes normal. If it's hugely excessive, drain the fuel and mix the proper ratio of fuel to 2 cycle oil and refill tank with the proper mix.

check the air/fuel mixture

It is normal for these bikes to use some oil. A typical, maintained 250 4 stroke will use a pint of oil or more in one day of riding - depending on a lot of variables, of course. Oil consumption on these four strokes is quite typical.

could be bad piston rings, or if its a 2 stroke engine (probably not) then you could have too much oil in the oil/gas mixture. maybe even too much oil in the crankcase.

could be too much 2 stroke oil in your mix or worse case, your piston rings are going.