I have a 97 cbr600 f3,full exhaust system but not jetted. I was riding fast,kinda light racing and it was fine yesterday and then today we took a ride down a known spot for fast bike riding and it was fine. got home and sat for a about 10-15 mins.Left out the house,got 5 min down the road and white smoke started coming out the tailpipe.

 

not a good sign. white smoke = water/anti-freeze in the cylinder. possible blown headgasket.

 

Yeah white smoke ain't a good indicator. Depending on the miles, but worn rings jumps to mind. There is a quite a few things that can cause it, even oil pressure/to much oil getting past the seals. Worn rings are usually indicated if it blows smoke under load, (accelerating) If you're burning oil, then keep an eye on the oil level.
My old beemer (boxer motor) had a diabolical side stand lean & that was enough to let oil get into places it shouldn't & sometimes starting her up made it look like it was on fire.
If you're lucky it may go away, if it gets worse then get it seen to before you totally scrap the motor.

 

okay so this morning i turn it on and let warm up,idle for about 10 mins,took it around the block,highest speed 15mph and let it idle for about 15 more min. and no smoke, weird? should i be worried?

 

did you recently change your oil? sure it was coming out the tail pipe?

 

no recent change of oil,but my oil level was low,so i added a qt. rode and hit about 55mph and midway between hot and cool meter and still no smoke..... the guy at my local bike shop says the whole situation sounds weird but is almost sure its a head gasket but if it was a head gasket it would smoke all the time.Last tank of gas i put some carb cleaner in the gas tank and maybe that was the culprit.only thing else i can think of is when i was riding my choke was open slightly so i closed it mid-throttle and that is when it started smoking

 

a quart low?!?! they hold 3.9 quarts. if you were running on 2.9 quarts the engine musta been hating you! dont think the choke would have caused white smoke. like i said, white smoke is caused by water being in the cylinders. reason i asked if you changed your oil is if you possible dripped oil on your exhaust. why did you put carb cleaner in your gas tank? i wouldnt do that, only seafoam. but possible the carb cleaner had the same effect and caused white smoke (which seafoam causes). id say keep riding it and see if the engine puts out white smoke again. did you run your tank empty of the gas/carb cleaner mixture?

 

i put carb cleaner in it bcuz i thought my carb needed to b cleaned because of a rough idle problem. I been googling and it could might be one of my valves.I have a rough idle maybe because one of my vavles "floating" and after running it hard it might have broke against my pistons..i been googling all day

 

how long have you had the full exhaust on there? is that the first time you rode the bike hard with that exhaust. the first thing i thought of was valves because you're probably pretty leaned out with not jetting it. the harder you ride the bike while its lean, the shorter the valve life. if you mostly just cruise around town, your valves will last a while (months, years). if you ride really hard (like a track day), your valves could check out on you in a day or two.