I actually had to clean my left side carbs up this weekend. Coming home Friday, I started getting a stutter under throttle. Found out the left side carbs were oily/dirty. I have a 99 RSV with 81K. This is the 3rd time this has happened (both the other times were right at 25K and 50K). I figure this is normal, since after cleaning everything up it runs like normal. Believe the blowback evertually fills up the left side a ways (after sitting on kickstand) and eventually some leaks into the carbs.