About our Jet Kits
Dynojet offers a wide range of kits to fit any application. Several types (stages) of kits are available to fit your specific needs. Whether you run a standard motorcycle, or a tuned sportbike, Dynojet Carburetor Jet Kits can provide you with a simple and affordable solution to all your carburetion problems.
Dynojet Jet Kits increase power and smoothness throughout the entire rev range, while maintaining optimum fuel economy. Each Dynojet Jet Kit includes comprehensive instructions which show step-by-step installation and testing procedures to ensure a perfect setup every time.
This is backed by free telephone and Internet support to Dynojet customers. Kit installation and Dynamometer services are available in many parts of the world. Please see the Dynamometer Center Search Page to locate your nearest dyno shop.
Jet Kit Types
Needle & Needle Jet Caps
Many newer bikes have very flat power and fuel delivery curves when used with the stock exhaust and air-box. When aftermarket pipes are used, the power curve is usually not flat. You find the need to lean out for low speed and richen up for top end; or leaner on the top end and richer at the low speed. In order to achieve full function and driveability, Dynojet develops shrouds or cap style nozzles for adjusting the upper or lower top end. They also have an effect similar to fuel injection by breaking up the fuel as it enters the air stream.
The design of the needle is where Dynojet spends most of its R&D time. The needle is designed to give the correct amount of fuel throughout the mid-range and is also designed to allow adjustment from groove 1 to groove 6 with little or no effect below 3000 R.P.M.; then with the correct end dimensions, the needle will have little effect on the main jet regardless of needle position. This isolates all circuits from each other and ensures easy set-up of the midrange and driveability.
Main Air Jet
This jet allows air into the emulsion tube to mix with fuel being drawn up from the float bowl. It controls the amount of fuel which can be pulled from the float bowl into the venturi. The larger the size of the main air jet, the more air you get and less fuel. The smaller the main air jet, the more fuel you get and less air. Dynojet alters this only to achieve the flattest possible fuel delivery curve.
This controls 100% of the engine idle and 25% of the transition onto the needle. Dynojet has found that the engine will idle with the standard pilot jet, with or without the air-box and with the slides and needles removed from the carburetors; therefore we never change the pilot jet. Doing so is proof that you are not using the other circuits correctly. Idle and off idle is controlled by the mixture screws and the float level which have the most positive effect below 4000 R.P.M. On some models the pilot air jet is changed to provide optimum fuel economy. Correct balancing of the carburetors also ensures a smooth idle.
We develop our main jets to correctly serve two functions; static load and dynamic load. The static load is the fuel received through the main jet in the upper gears, where the tachometer is moving very slow. The dynamic fueling portion of the main jet is the amount of fuel received from the jet in the mid-range potion of the power. For example, you have a GSXR1100 G,H with #130 main jets. You then install #125 mains. After running the bike you notice the top end has improved but the mid-range doesn't pull as well. You then install #135 mains and you notice the mid-range is great but the top end is slower. This is a common compromise when using stock main jets and needles. If you install Dynojet 130 mains, you would get the mid-range power of the #135 and the good top end of the #125. This is because the Dynojet main has a venturi design more consistent to the engine's needs.