46 ax engine tunning problem

by kamal chandel
(ahmedabad gujarat india)

Hi,

I have a new 46 ax engine. My problem is after break in ,as I spent 12 to 15 tanks of fuel, my engine is not gaining maximum rpm.

Rather it is running four stroke even while at 2 turns from fully closed position.

But even worse thing is when I slow down the throttle the engine gives the full rpm. But at full throttle the rpm drops and it sounds four stroke running very rich.

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46 ax engine tunning problem

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Dec 18, 2009
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Still too rich on the high speed needle.
by: Michael from Oz

G'day

Your carburetor has two needles. A low speed needle and a high speed needle. The low speed needle is the one you adjust with a screw driver, the larger high speed needle is the one you adjust with your fingers.

The low speed needle affects the mixture over the lower 85% or so of the throttle range. The high speed needle affects the top 15% or so. They both interact over the whole range.

Your engine sounds to be too rich at the top end and so you need to lean (screw in) the mixture with the high speed needle until you get absolute maximum revs BUT NOT FURTHER. Then with the needle peaked, adjust the low speed needle for best idle and transition. As the needles affect each other, you should then re-adjust the high speed needle for max revs and then check the low speed. When you are happy with the high speed needle, then richen the mixture at the high end by opening the needle about one quarter of a turn or if you have a tachometer, reduce the peak revs by 300 or so RPM. This should be your flying setting.

It is safest to do this with the tank about half full as when the tank empties, the mixture may become a little more lean. Lean settings are the worst thing you can do to your engine. The engine will run hot and may be damaged.

Have fun and let us know how you go.

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Dec 18, 2009
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Submitted by: Michael from Oz

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G'day Your carburetor has two needles. A low speed needle and a high speed needle. The low speed needle is the one you adjust with a screw driver, the larger high speed needle is the one you adjust with your fingers. The low speed needle affects the mixture over the lower 85% or so of the throttle range. The high speed needle affects the top 15% or so. They both interact over the whole range. Your engine sounds to be too rich at the top end and so you need to lean (screw in) the mixture with the high speed needle until you get absolute maximum revs BUT NOT FURTHER. Then with the needle peaked, adjust the low speed needle for best idle and transition. As the needles affect each other, you should then re-adjust the high speed needle for max revs and then check the low speed. When you are happy with the high speed needle, then richen the mixture at the high end by opening the needle about one quarter of a turn or if you have a tachometer, reduce the peak revs by 300 or so RPM. This should be your flying setting. It is safest to do this with the tank about half full as when the tank empties, the mixture may become a little more lean. Lean settings are the worst thing you can do to your engine. The engine will run hot and may be damaged. Have fun and let us know how you go.

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