have a 97 CBRF3 600, i just put a two bros exhaust on it,its a little sluggish between 3 & 5k, after that the main jetdoes ok & VOOOOOOOOM.... was thinking i need a jet kit, gonna buy a stage 1 dynoJet, is that good enough though... i read that most stage 1 are for the stock setup.. But i heard that changing the exhaust will lean it out.... need to rich-in up my ratio,, its mostly stock far as i know, stock airbox, stock headers, air filter--dunno.gotta check. It has the C-series 2 BRO slip on pipe.. any advice would be much appreciated!! thx!!!

 

First, these bikes have a flat spot in the power band up to 5 to 5.5k that no jet kit will cure. with just an exhaust, your bike isnt running lean enough to need jetting. the only cure for that is an ignition advancer, and you need to have a few more things done before you worry about that. as for the stage when its time to jet, you will be looking for a stage 1. unless you are running overbored pistons, cut valves, and ported and polished heads, and a few other internal racing parts, you will never need any more than an stage 1.

 

There is a way to fix the flat spot. Search for it. I've only seen stage 1&2 jet kits avaliable. Imo I would rejet with your exhaust. A ignition advancer wil do little to nothing...

 

I didnt have the money to buy some overpriced brass i modified my own. I installed k&n filter and one of them stubby moto gp pipes, I had a bad flatspot 4500-6000k. I did alittle experimenting took out the four jets mine came stock with #135's. I used a drill press and 1/16 drill bit and carefuly drilled a bigger hole, screwed the idle mix screws all the way in and turned out 2 revolutions out. Bike runs alittle richer and right on the money quick throttle response no hesitation no surging im very happy.

 

Thx guys, advice much appreciated, it had a D&D exhaust on it but it got damaged in my accident last summer.(bike did a couple endos). it seemed to run ok with the D&D but still had the flat spot, ive dumped 1500 into this rebuild ((would be 2200 if i bought everything new))& figured if im gonna put this much into it i may as well go all the way & get a jet kit, .. im replacing the whole front end today, as i found that the forks are bent & dunno if the bearings are ok or not,, so its all getting replaced...hoping for a great turnout. Wish me Luck! 1st time ive done this kind of work on a bike.

 

Project bikes are always fun

 

Ive got a 91 f2 got it last thanksgiving day and dumped 1800$ in already im addicted.

 

Right on, yea it deffently has me looking foward to getting to the weekend & to get home to track my parts, just ordered a HID converter kit, tried to get away with a aftermarket bulb.... Big mistake, was drawing to much juice & burnt my connector. HID better anywayZ. Total cost of everything ive done is about 1600$ now, got a couple small things to get yet,, flush mounts, backtire. bike gonna look newly Sweet! With bike & all total is 4000$.. Not bad for a sweet bike & great times. Btw I think this forum kicks 4$$. U guys Rock!