sorry if that was mis-understood. I was referring to using the O2 sensor as a tuning tool. In general, if you go to a larger main jet, you will see higher numbers on the O2 sensor under significant load. I'm not claiming to be an expert on carbs, but I was under the impression that the power valve determines *when* the transtion occurs from low speed to power enrichment, and the main jet determines *how rich* things will be when it occurs. Please tell me if I missed on this. I only pretend to be sure about stuff around my wife <grin>, but she sees right through it. Mike V
