Dyno jet kit?

TnT · 04-09-2008, 2:54 AM

Howdy All, I have a beautiful '93 FireBlade and have recently fitted a BMC airfilter and a full free flow Kerker exhaust. But I am not sure if I should fit a dyno jet kit. Any suggestions? I will have it dyno tuned afterwards. I am only considering it as I feel it has a slight flat spot between 4 and 6000 rpm. The power above 6000rpm is grin inducing but two up and in 5th and 6th there is definately a lag. Any help is most appreciated.
Tim

jdugen · 04-09-2008, 8:00 AM

Put a Dynojet on a standard bike, they all run too lean, a must with a modded bike. Gets rid of lags and flat spots a higher altitudes when the standard carburation really struggles.

TnT · 04-09-2008, 9:06 AM

Thanks very much for the advice I will definately do. By the way how badly does the jet kit affect the economy?
Thanks again Tim

BikePilotRR · 04-09-2008, 9:37 AM

It doesn't affect range very much at all...jet kits generally put a bigger main jet, and a different tapered needle to put more fuel in the airstream of the carburators, to hopefully put your air-fuel mixture a little closer to the desired 14:1 carburation at all throttle openings. Once this is achieved, your motor will run MUCH more efficiently, produce better power across the rev range..so to maintain a certain speed, you will likely be able to have less throttle open at any given cruising speed. So you can see that it more or less balances itself out this way-- more fuel in the air mixture, but throttle trimmed back a bit = no much change in mileage. Besides, the key here is cruising speed...as a streetbike rider, you are not likely going to have the throttle pinned back all the time. Your fuel mileage will be affected mainly in that spot of the throttle that you spend most of your time, while cruising, since you only spend a fraction of the time cranking open the throttle to accelerate.

TnT · 04-09-2008, 9:52 AM

Thank you very much for all the help. I now just need to get the bike booked in for the new jet kit and a dyno tune. The last dyno run I had done was before the Kerker exhaust was fitted and I was getting 117 Hp through the back wheel. The bike above 6000rpm feels fantastic but I'm sure with the dyno jet kit and a good tune it should be a lot better.
Thanks again Tim