Maybe this will help. First check the spring tension on the secondary upper blades by pressing them down with you fingers. They should have enough tension on them to open then when you release them snap closed. If they don't snap closed and stay open this will creat a bog. The adjustment for the tension spring is on the left rear corner of the carb underneath the casting as your standing in front of the vehicle. Now if tension is ok open your thottle blades wide open by hand (engine not running of course) and look just below the choke housing there will be a Z type or S type stop which falls off when thottle is off open. the Choke fast idle cam controls this in the cold mode so secondarys don't open, as the engine warms up the Z or S stop is allowed to fall away and thus secondary blades open. The top blades are controlled be the vacum of bottom blades as they open. Hope this helps you. Bestbbq, No. Cal