I hope there are more clever people here than I am. I've been tuning my Moki 250 intake and exhaust ports so the there are no sharp bends and that the flow does not experience any unnecessary turbulence. Now I'm in a situation that with the tuned head I need to turn High and low needle half a turn richer to get it running smoothly. And still it takes the same revs than if I put my old non-tuned heads. With the non tuned head again I can close the needles by half a turn. So definitely the engine is getting more fuel/air mixture but why there is no rpm increase? All I could think up was that the droplet size would be bigger now with opening the needles and thus burning slower. Or could it be that there is now just more torque at lower rpm's? I did notice that it is responding better with the tuned heads. But I was expecting higher rpm with the increased fuel consumption.