Motorcycle Repair: 1985 Yamaha FJ 1100, air screw, yamaha fj

Question
QUESTION: I recently bought a 1984 FJ 1100. Ive sync'ed the carbs,changed the plugs and all the electronic ignition components test OK but it consistently breaks up at around 3000rpm,gets worse after running for a while. The bike has a vance and hines exhaust. Any advise will be greatly appreciated. Thanks, Art

ANSWER: Could you tell me have the carbs been jetted for the after market exhaust system?? If not you will have to give them a call and see what they recommend for jets for your bike.

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QUESTION:  Hello, Thank you, unfortunately no one knows weather it's been jetted or not. Can you tell me which jets have to be changed when using aftermarket exhaust? Thanks, Art

Answer
What you are going to have to do is call you local Dealer. Ask  for the parts or service department (I ask for parts because service can be fussy sometimes about giving information) and tell them you need to know the stock settings for your bike and write them down. You need to know the main jet size, pilot jets, needle clip position, and air screw setting. Then compare to what you have in your carbs. If the carbs have what they are telling you then you will have to rejet. All exhaust systems are different and jetting is impossible for me to tell you verbally. I would have to be with th e bike take plug readings, listen to how it sounds and how it responds to the flip of the gas. The maker of you exhaust can tell you what they recommend because they have records on hand of bikes they tested this exhaust on and may even be able to supply you with a jet kit. Let me know if you need any more help as I will do the best I can over the comp...