Start by checking ALL of the hoses for splits. Often the fuel line form the high speed needle to the carb cracks, and you cannot see it, at the nipple. Check that the clunk does not sit up against the back of the fuel tank. e.g. there should be SOME seperation from the back wall of the tank.

Loosen the carb hold down screw and seat the carb fully, and while holding it with some force with a clamp, tighten the screw back down.

Also tighten all of the cap screws.

Next remove the LOW SPEED "collar" ( the blue thing with the pin ).

Then with the throttle closed ( use the radio to do this ) turn the low speed needle IN until it bottoms out. DO NOT FORCE IT!
As you do this count the precise number of turns and write it down.

Now remove the low speed needle and apply a SMALL drop of Loctite only on the threads. DO NOT get Loctite on the rubber rings.

Put it back in exactly as you had it before, but this time with no blue collar.

Do the same for the high speed needle and tighten the "Bic Pen" retaining/friction clip too.

Start the engine and retune with 1/2 of a tank of fuel, no more.

Since the plane is new it will not really "settle" in until it has gone through about a gallon of fuel. Bear this in mind.

Run the throttle up fully and bring the nose up.

Does the engine seem to stop almost immediately or slow down as you bring the nose up? If so richen the high end needle 1/8 turn and try again until the engine continues to run fine.

Now still at full throttle do a nose down test. The engine SHOULD slow down a bit, but it should continue to run if you have the high speed needle set properly.


Once you have this working, it's time to set the low speed.

With the engine at idle pinch the fuel line for about 1/2 a second. You should hear the engine speed up a bit but it should NOT die out.

If the engine dies out, richen the low speed.

Now, run the engine at full throttle for a few seconds and bring it back to idle.

Let the plane sit idling for 2-3 minutes. As it does this there should be NO or only a slight tendancy to slow down and the engine should continue to run.

If the engine slows down lean the low end a tad and see if the idle improves.

Once it idles consistently gun the engine quickly. The runup should be smooth with no hesitation.

Finally with the engine at idle perform a nose up test. The engine should NOT cut out. If it does it's too lean.

Fill the tank and then perform a nose down test. If the engine cuts out, it's too rich.


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Evolution engines tend to have the limiters "walk" as the plane heats up and you move the throttle.

You could have the plane perfectly tuned only to find that it will detune itself over time.

The above helps to prevent the needle "walking".