96 sportster 1200 up grade from 883 need help

Hi I'm knew to Harley but I'm mechanicaly inclined was a auto tech for 9 years. My problem is it lags or shutters in first gear and sometimes when I snap the trottle in any gear. I think its related to the carb so i removed the Carb an checked the components. I discovered that the rubber diaphram was sticking out the top cover pinched, is this a possible problem? The needle is a n65c the main jet is 180 an the slow jet is a 45 what should I do. Thanks.

thats your problem,if the diaphram dosnt have a good seal,the vacuum wont pick the slide up

So the jets that's are in it are fine for the 1200 swap?

jets sound good,you have to be very carefull with the diaphram,when its right,if you move the slide up with your finger,youll get a kinda vacuum sound,if it just goes down with the spring,you still have a leak

Thank you for the quick replies I ma get a new diaphram tomorrow,I'll will post up the results thanks.

Thanks bro the bike has a crap load more power. The shutter or hesitation in first its alot better but still acts up. Will this go away after a few miles or is there another tweak that I can do?

as long as the diaphram isnt leaking,it still could be jetting.but the jets you have now sound pretty close,try a 42 slow jet

Ok thanks. I don't believe the diaphram is leaking I put a knew one in an there was a steady vacuum when the slide was moved at anytime. I just took it out again an it seams to be cleaning up I think the plugs were fouled.