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Adjustable power jets for Tdr250.

I have just fitted adjustable power jets on OEM carbs of Bill's(GR) Tdr250 bike. It is a tight fit on Mikuni 28mm carbs but doable.

Power jet is really necessary for a two stroke engine as you can fine tune the mid rpms at a far more exact range thus improving throttle response and when at top rpms, the power jet kicks in to supply the extra fuel needed by the engine. Having two metering systems to supply the fuel at top rpms means better fuel atomization as well. Forget about "bogging" and "4-stroking" while using huge main jets at slow speed cruising. Fuel consumption is going to change as well, as you'll be running about 20% smaller main jets.

This type of power jet is externally adjustable, meaning that you do not have to strip the carb to adjust for different fuel requirements. Turning the knob clockwise-anticlockwise will lean or richen the mixture respectively. Each 1/4 of a turn equals one step in the size of a regular main jet with all the increments in between.

Really recommended for all two stroke junkies out there.
Here is a photo... though the carbs still need to be cleaned.


  1. Good job Nick...
    I like your work very much !!!


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