When I start my TBA and it has not been riden in a few days I get white smoke coming out of the exhausts for about 30 seconds to a minute and then it stops and everything is fine. I have noticed that when it does this that there is a small amount of oil at the tip of the exhaust. Any ideas as to what causes this? Is it a problem that I need to be concerned about? Is there a way to correct it? Any help would be greatly appreciated. Thanks.