Yamaha Phazer II carburetors
I have two old Phazers; I've been tinkering with them for 15 years. Phazers have butterfly Mikuni carburetor units; (they are fastened together)I'm trying to tune them for performance with an Aaen, SLP, and (makeunknown) pipes and not having much success. I have three different carburetor units that I can test out my sleds with. I can swap the units from sled to sled and get the same results in performance. All jets have been cleaned thoroughly and the carbs sprayed out with carb cleaner.
I ride at about 8000 feet and one of the carb units currently has #56 pilots, #145 mains, and #3 needle jets. It blubbers, and keeps blubbering with very poor power soon after the initial surge of power from the pilot jet.
The next carb unit with #56 pilots, #140 mains, and #2 needle jets starts strong and then dies until the choke is pulled. At that point, with the choke out, it performs quite well as long as I'm full throttle.
The third carb unit is still jetted for stock pipes with a #50 pilot, #131.5 main, and a #2 needle jet. (There is no needle in a butterfly carburetor.) This carb has to be choked to get the initial surge and then as it accelerates it requires quick pulls on the choke to keep going.
I disassembled the fuel pump and checked the diaphram and all three carb units start the sleds first crank. Can anyone out there give me some advice on what to do?