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was shown a cool trick yesterday to check to see if your needle and seats are good or not, it involves making a pump out of a blood pressure meter some gas line and a low pressure air gauge(round needle gauge like one to check low tire pressure on atvs 0-15 psi)and some plastic fittings(a "T" and a coupler).separate the ball that you sqeeze to pump up the pressure with some of the hose attached "T" in the low pressure gauge couppled to some gas line the size you are using.remove the carbs from the sled drain fuel and attach the "pump" to the fuel intake on the carb and put under pressure(5-6 psi) if it hold the needle and seats are good if the gauge drops they are no good.just thought i would share this info for those who don't know about it.

If your a kart racer, that's a very common and cheap tool, its called a pop off gauge. There used on Tillitson carbs to set the pop off pressure. Their available at any kart shop or mailorder. On Tillys, your looking for the exact pressure the valve "pops" or opens. With our carbs here, even tho I have several of these gauges, I just blow on the end of the hose. If it seals with light presure, the air flow will stop, completely. If its leaking you can feel the air go threw.