Why does my mower hunt when I put Hi-Lift blades on it? I have a 52" Scag with 17hp Kawi engine, hydro. It's an older model but the engine is fairly new. When I bought it used I changed the air filter, fuel filter, oil and filter and both plugs. It runs fine with Gators, but for some reason not with Hi-Lifts. I didn't fiddle with any adjustments on the engine yet. I don't have a tach to see how fast the engine is running. Maybe it's not at full rpm??Thanks Dave.