The oem carb on this engine had a rich stage just off idle that would not tune out. It was a brand new adj carb too. I sold it on ebay and I bought a new 26mm Mikuni and bolted it on. The air filter is from a set I bought for my GS 750 Suzuki. This carb works so good. I have the needle on the leanest step and its just a tad tad rich but now I can change the pilot jet easily!