Carb Tuning

Make sure you dont have a small vacuum leak somewhere. This would require the mixture screws to need to be adjusted out. A little trick I do if I suspect an air bleed or mixture restriction from dirt (it doesnt take much to throw off the idle mixture) grab the throttle and choke plate, rev the engine, as the engine speed picks up close the choke plate. This will flood the engine and should keep the engine from overreving due to the lack of air entering the motor. Do this three or four times for SHORT THROTTLE BURSTS. Something in the 4000 to 4500 rpm range should be safe on a healthy motor. Clear the engine out without closing the choke after each time. What this will do is allow manifold vacuum to be really strong all the up to the choke plate. Sometimes this will help clean out the small passages in the carb. Under normal operation high vacuum is only applied to the very bottom of the carb. May sound crazy but it works for me.