Well i finally put a 38 keihin on my 86 250r. I was a little worried about losing bottom end but i figured i would try it. I have a ct mid ported cylinder and paul turner pipe with a boyeson rad valve. When i finally got the carb dialed in i was impressed to say the least. I could pull hills and just about everywhere a gear higher due to more hp. I would say a 5-8 hp increase over the stock carb. Lost a VERY LITTLE bottom end and it absolutely rips mid to top. Any body thinking about this mod i highly recomend it!