From your description IMHO it's going to be valve guide seals. Rings don't reseal. With rings, once they are worn, they are worn. Oh sure, once in a while I will see rings gummed up and stuck in the lands. With good fuel and good oil hat is very rair.

If you have worn guides and/or hard seals the oil will wick down the valve stem on shutdown and when you start the engine up the combustion chamber will have some oil to burn off. This takes a while but once burned off, your good to go until the next time you shut the engine down.

Another way to check this is to go WOT down a road and then close the throttle down all the way and let the quad coast to almost a stop. Then jump on the throttle and look as the end of the pipe. If the seals are not doing their job you will see a puff of smoke out the pipe.
By doing this you are putting the intake track into high vacuum so if the seals arn't doing their job you will know.

Another way to check is to do a leak down.

 

If you have overfilled the oil a little bit and run it at WOT throttle then it'll smoke sometimes. Especially if you wheelie. What happens is the oil gets pushed out of the crank case due to the extra pressure from the extened WOT run. The first thing I would do is check the oil. It doesn't have to be on the top line on the dipstick to be fine. If your bike is showing the oil on the top line or over on the dipstick I would bet that is what happened. I always try to start simple and go from there and that is about as simple as you can get. LOL If your oil is right at the middle on the dipstick then I would give the DR.s advice a try. I wouldn't think in the amount of time you have on your bike that you would have very worn valve guides. But I don't know what it's been put thru or how it was maintained. So that's just an assumption based on what you said about you mantainance. I do know that your heat indicator should not be coming on. If your bike is still stock then you need to clean out the radiator and make sure it is flowing. If you've done intake and/or exhaust mods then you need to get it on a dyno or a/f meter and get it jetted. ALWAYS remember running an engine at excessivly high temp is going to cause engine wear to accelerate.

 

Thats good information, ugh I'm right before buying a new truck, dont really have the money to put it in the shop and have the carbs rejetted and valve guide seals checked, preciate the replies turbo and fast, as for your assumption of maintenance it has been takin care of, the extent of its abuse is only somewhat frequent romps on the throttle and thats about it. Heck my wheelbearings still feel pretty much as tight after 2250miles as when they were new, i.e, few dunkings in mud and water lol. I guess I'll just keep riding it for now, and when the money is more easily obtained I'll carry it in and have the carbs rejetted and may have them check the seals. thanks.