i have a 90 gsxr750 just got done rebuilding from the frame up. ran fine about a year ago, got the carbs synced and it has been sitting since while we were working on other stuff. so we went to finally start it up today, and it's running like crap... it will start and idle but only with the choke open all the way. if you try to close it some it immediately dies. it barely revs up and it seems to bog after a sec, then stall out. but it will always start right up after that. it seems like the 2 center cylinders are running fine, but the 2 outer one are not. there is spark in all 4 cyl. fuel is ok, and it's getting air.... have switched out the computer, magneto, and ignition coils with spares and it doesnt change how it runs.
any ideas?


and yes i have searched, but flame on if you must! :blackflipoff2:

 

i have no personal experience with this bike or any carb'ed bike but i know that fuel can gunk up if sitting for a while. try cleaning the carbs and fuel lines to clear everything out.

 

Your carb jets are gummed up - most likely the idle jets, but they all need to come out and be cleaned - soak them in simple green for an hour or so, then blow them out with compressed air. Blow out all the passages in the carb bodies with compressed air too.

 

sorry to threadjack but i cant find any other way to get a message to .RJ, need to ask you a few questions about that beautiful cb750 of yours, if you could please email me at 03civex@gmail.com i would greatly appreciate it...sorry again b16_ef