Difference between revisions of "Jetting"

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==Fuel Screw==
==Fuel Screw==
The Fuel Screw is mis-labeled in the Yamaha manual. It is labeled as an "Air Screw". This is 100% backwards. Air screws are on two stroke carbs. The last I checked, this carb has been on this 4 stroke engine.
The fuel screw allows more fuel through the pilot circuit. This very definitely affects low speed operation. To allow more fuel flow or richen up the bottom end, the fuel screw is turned counter-clockwise (or turned OUT). This IS richening up the bottom end.
The fuel screw allows more fuel through the pilot circuit. This very definitely affects low speed operation. To allow more fuel flow or richen up the bottom end, the fuel screw is turned counter-clockwise (or turned OUT). This IS richening up the bottom end.
To lean it out, the fuel screw must be turned clockwise (or turned in). The problem with this low speed/idle jetting is it is too lean. The only time I think you would turn it in is if you decide to ride your TTR into the Rockie Mountains, where bikes are starving for air, which ain't there!
To lean it out, the fuel screw must be turned clockwise (or turned in). The problem with this low speed/idle jetting is it is too lean. The only time I think you would turn it in is if you decide to ride your TTR into the Rockie Mountains, where bikes are starving for air, which ain't there!

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