quick question on a jetkit....i have a 99 honda CBR600F4, 9k miles, with a Akrapovic full exhaust, someone who i trust that rides bikes and can work on them suggested a jetkit....should i just stick with a stage 1 or 2 at most?
thanks for your time, sorry if this has been discussed before, my apologies (ive seen some people on my wrx site get nasty bout that but I did search...anyways) but I still wanted to ask myself...

i figure maybe a stage 2 but i dont think i plan on doing a aftermarket air box or air filter....

thanks for everyones time

Paul

 

Go with a stage 2

 

I run the stock exhaust on my '99 F4, and I plan on keeping it that way. However, I intend on putting in a jet kit. I am not a newbie so don't worry about me being "another squid who wants power he can't use". Anyway, I find myself longing for a little more umph exiting corners, and an effective way to get mor power out of my bike. I also want to keep fuel economy up if possible. I have heard good and bad things on all stages (1,2,3,7- 3 and 7 being out of the question). The debate lies in which one, stage 1 or 2?

Thanks in advance!

-Ian

1999 CBR F4
Michelin Pilot Powers
Suspension stiffened to race setting (holy crap, what a difference!)
Vortex Lightweight Drive sprockets, OEM gearing (front and rear)
RK 525XSO race chain
K&N airfilter
Puig Race Windshield (again, what a difference!)

*adding clearance plate to stock muffler, look up 1992 GSX-R 750 stock exhaust to see what I mean...
*making brackets (6061 T6 aircraft grade aluminum) to move rear-sets up and back 1"

 

I wouldn't change your jetting if your not going to be pumping in/out more air, you could end up losing power. The Honda has it stoich (optimal air/fuel ratio).

 

So I'm going to sync my carbs, I was thinking while I was at it to put a DynoJet on it. So you saying I should add a K&N to get more air/ratio? Is that how they work?

 

Basically yes. K&N's are less restrictive than paper elements (more air) and a good exhaust system will allow the engine to expell the extra exhaust gases faster (less backpressure). But depending on the jet kit you buy, it might require you to do needles/springs/shims, main jets, slow jets and some even require carb bore adjustments. Stage 1's typically work best with lightly modified engines, a good air filter (K&N or whatever) with a good exhaust and a stock airbox (your airbox pressure controls carb pressures, especially with a ram air intake!).... But then again, you might not need to put in a jet kit after an air cleaner/exhaust or both. Personally, the only time I would put in a jet kit is if there is a flat spot in the rpm range (she bogs for a split second and then powers on again) then jetting is deffinately required, your carbs aren't staging properly (the transition from slow jet to main aka the metering) and she's probably leaning out a little. When you put in a jet kit you will also need to adjust your pilot screws. If you're just adjusting the mains, I'd base the jet size more on altitude than anything. Other carb mods you might consider is changing the velocity stacks. If done properly, you should be able to adjust torque/ponie curves and really fine tune the carbs for the way you ride.
If you don't know how carbs truely work, try not to mess with them or you'll have to learn all about them real quick. It cost me alot of saddle time learning about carbs the hard way Try to read up a little on them before you start, you might learn even more than you expected and get even better performance gains from your new knowledge. Hope this helps.

 

So on a Factory Pro kit, or a DynoJet kit, they don't come with all of that stuff? (Needles,Springs,Shims, Mainjets,Slowjets)?

 

i got the dynojet stage 1 and all that stuff came with it, jets, springs, pilot screw, ect.

 

The used F4 i bought was still bone stock and i havent done anything yet. When i feel i can afford it, i'd want to do a stage 1, slip-on, K&N, and ignition advancer all at the same time.

 

You'll be fine with a stage 2, i have a stage one i my bike right now. It just feels like a fuel injected bike (starts to pull a little lower, and a bit harder through the power band)