The kit contains:

One Adjustable Power Jet

One Hose with clips

One Brass nipple

One Screw for securing the Power Jet

One Transparent rubber cap (not seen in pic)*

*please use this rubber cap under all conditions as it prevents the adjuster screw from unsetting. Still adjustable with the cap on!

Why Power Jet?

When jetting a carburetor for a highly tuned two stroke engine it goes without saying that you choose a main jet large enough to avoid engine seizure at full throttle. This however inevitably results in a too rich mixture at WOT at lower revs, before the the engine has gained speed, resulting in a slow throttle response.

The solution

To get quicker throttle response at full throttle from lower revs the main jet size must be decreased. To do this without risking a seizure at full power the Power Jet is the solution. This extra circuit makes it possible to reduce the the main jet size without causing any danger. The smaller main jet will make the engine respond more rapidly from lower revs up to the power band the Adjustable Power Jet secures a correct fuel mixture at full power.

        The decrease in main jet usually works fine with 25% smaller size with the same amount of increase on the Power Jet. This means that if you are running a #180 main jet without Power Jet you drop down to a #135 main in the carburetor and set the Adjustable Power Jet to 1/2 turn. If the engine now runs too rich on top, just adjust the screw clockwise until you find the correct Power Jet size. In the table below you can see the corresponding Power Jet settings in relation to main jet sizes.

The Adjustable Power Jet has a flow span corresponding to Mikuni hex (4/042) up to # 350.

Corresponding approx. flow: 

• 1/4 turn     =   #60 
• 1/2 turn     = #110
• 3/4 turn     = #140  
• 1 full turn  = #170  
• 1 1/4 turn  = #210 
• 1 1/2 turn  = #250  
• 1 3/4 turn  = #300  
• 2 full turns = #350       

Adjustable Power Jet dimensions:

Total length: 82 mm
Brass pipe length: 28 mm
Tube diameter: 4 mm
Hose dimension: id 4.0 / od 7.5 / L 195 mm

Things to keep in mind when assembling

You will be needing a 4mm drill bit for the power jet's brass pipe. The location of this hole may vary depending on the conditions. Some carburetor bodies does not have enough room for a Power Jet why you have to find other solutions. There are many options to locate a Power Jet. It can be mounted from above or from the side. However regardless of the location, the brass pipe nozzle MUST end up in the centre of the carburetor throat (… the pipe may need to be cut to the correct length). Since air velocity is what affects the power jet’s ability to suck fuel it is important that the nozzle is mounted in the center so that the incoming air passes over the nozzle orifice at right angle (see pictures).

         The kit comes with a screw that secures the power jet to the carburetor. If you choose this location, you will need a 3.3mm drill bit and an M4 threaded pin. If you choose to mount  the Power Jet in a rubber hose it is OK to clamp the Power Jet's mounting ear under the hose clamp (5) or use a self-tapping screw directly into the rubber.

         If your carburetor is equipped with a overflow tube, you do not need the nipple attached in the kit. Instead you just remove the narrow tube of brass inside the float bowl and simply mount the power jet hose to the connecting nipple on the outside (pic 2). If you do not have an overflow circuit, then you have to use the supplied brass nipple and drill a 3.9mm hole as close to the bottom of the float bowl and securing it with Loctite.