I have 1996 cbr900rr that I just picked up, and seems to run fine/idle, mid range, but seems to sputter/surge at full throttle??? 1st 2nd and maby third feel pretty good, but after that under full throttle it sputters. I cleaned carbs, they looked good and this help low end a little but no help at full throttle. It has 116 main jets for all 4, and I set the idle set screws to 3 turns out. Any ideas??? Do I need larger jets?

 

I recently installed a Factory Pro Jet Kit in my 96 and when i took out the main jets the outer cylinders were 115 and the inner cylinders were 118 depending where you are located they may be correct or they may not. if you have added a pipe air filter or modified the exhaust you may need to rejet the carbs. According to Factory pro you start with the main jets and find the correct ones following the directions on their site. For example with the modifications i had made i went from the 115/118 setup all the way to 130/132 now with it being cool yet i have to wait till it warms up to see if i can go to 132/135 then fine tun the rest..

if you think you need to jet it warm the bike then pull on the choke full so it stays on then do a fuul throttle run if it pulls you can go up in jetting if it boggs out the mains are correct.

 

what you should do is learn to read the plugs. go to a straight relatively secluded road near you and do a full throttle pull into the region where you are experiencing your trouble, and at the same instant hit the kill switch and chop the throttle and pull the clutch in. to get an accurate plug read you will need to have it stop running and the engine stop spinning right in the rpm/load where you experienced the stumbling. check the plug on the side of the road. these bikes it's not all that easy though i suppose. consult this chart:


and make your assesment which way to go, down or up a size.

the other option that is a lot easier and doesn't involve wrenching on the side of the road is to get a wideband o2 sensor such as an innovate LC1 and tune via that. it's more accurate for most people who arent experts at plug reading but is a good bit more expensive.

 

I would venture to guess that you may want to have the air screws set at 2.5 turns out and make sure the needle circuit is set on the third clip possition from the bottom and yes if you have a pipe and k&n filter you will need to change the mains for sure