I have all the Redline tuning kits available for the 44 IDF's. One has main jets sizes and air correction jets, one comes with different idle jet sizes and it comes with different accel. pump what I call squirter sizes and different size bypass valves to let 50% bypass or zero bypass that gives you 100% of the pump squirt going down the carb throat. The carbs come with the 50% bypass installed. You can also adjust the amount of accel. pump volume by turning the small nut on the pump arm in or out to fine tune more or less accel. pump action. The Weber IDF carbs are very tunable and most of the tuning can be done without carb removal. I have gotten to the point I will need to remove the carbs to get them perfect. Mind you it is so close now that many if not most would not know but I know and I want it perfect. Now if this engine winds up in a different elevation it will need some fine tuning to run well. Makes a good argument for fuel injection. I have spent over $400.00 on jet kits to tune the carbs. That and the $900.00 for the new carbs get's me maybe a third of the way to a CB Performance FI setup. An old school VW buddy went Fuel injection about 5 years ago and swears by it and will not run a type 1 any other way.