MasterTune Overview


MasterTune Patent # 6,655,665 B2 eliminates the need to change a main jet, forever.

No more guessing in the morning or in the starting line. Aircraft quality design and materials with tight tolerances that allow this valuable investment to perform in top condition all the time. MasterTune has been flow-tested in England by Mike Hemingway of UK Racing Spares Ltd., a company dedicated to the preparation of Aprilia Grand Prix motorcycles.

The standard plug and main jet come out of the carburetor. A new oversized, re-designed jet goes in, and the new plug is installed. As simple as that.

Follow the initial set-up instructions carefully and concentrate on driving the kart, the MasterTune will help you adjust the main jet while you drive. Start your first practice session rather rich, and lean it down to optimum following the EGT temperature rise. Read the spark plug as always, to confirm the EGT reading and enjoy the drive, you will never need another main jet change,

The whole assembly takes ½" on the bottom of the carburetor, so make sure you have the proper clearance. The flexible shaft can be installed with the knob near the spark plug, if you have a different requirement, the shaft can be cut at any length.

The adjustment is very precise, the range is 3-½ turns on the needle from fully closed to fully open, which represents a 254 jet in a 39mm Dellorto carburetor. The 5 to 1 reduction gear allows the knob to turn 16 times, and it has four clicks per turn, each click representing approximately one half of a number of a jet size.

In the morning when you practice, the air is good, cooler and has more density, so the knob will be turn to rich, and the EGT temperature monitored. At race time it is usually afternoon, the air is less dense and warmer, so the knob will be leaned. Even in your parade lap(s) when you are not flat-out, you could lean it a bit to avoid flooding the engine and eventually fouling a plug , and open it up to the normal setting as you accelerate across the green flag.

Every race weekend you should start from scratch, meaning turn the needle in until it bottoms, and open 7 turns. This should set the carburetor rich for almost every race track out there.

Racer Investment: $379.00 plus $19.00 for shipping and handling within USA .

Dealer inquires welcome.

Call MasterTune Racing today!

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