Hey guys, I'll try and get straight to the issue here, any help is appreciated.
78' kz650 B2 with VM24SS (1020A serial # on the body) carbs, all stock everything except dyna ignition and a bitchin paint job. I am experiencing a short hesitation, repeatable at about 1/2 throttle or so when I am rolling on the throttle to accelerate, hard, slow, doesn't matter, I can always repeat the hesitation at the same throttle position. the effect is far worse in 1st gear and is less noticeable in 5th, I assume due to the torque of the lower gear amplifying the effect. After the hesitation it takes off as expected and is strong all the way up to red line. It runs fine, starts fine, comes off choke after just a few minutes. I rebuilt the carbs with the stock jet sizes, 102.5 mains, 15 pilots, O8 needle jet, y63 (5DL3 replacement) jet needle on the 4th setting (I have tried 3rd and 5th setting, same issue), and I have the air screws out at about 1 1/2 turns based on best idle. carbs are in sync, The floats were adjusted using the clear tube method and they are within spec (1mm within 3mm from base of carb body). all lines are new, air box is new, air filter is new, spark plugs are NGK NE7 and they look perfect. Everything is new and in order. I am at a loss.
The only thing that comes to mind is the Y63 jet needle not being the correct profile and causing an issue at the transition point from pilots to main. Can anyone give me an idea as to what needs adjusted to get this thing running right. It also seems strange that my air screws are only 1.5 turns when I believe stock should be around 2.5, this leads me to believe that the pilots may be lean and they just don't have enough juice at the transition from pilot to main. I'm about to slap some 17.5's in there tonight and see what happens but I'm open to advice
Thanks in advance, I apologize if this is the wrong place to post this, I'm new!