Walbro Wj Carb Manual
I have a relatively-new Area 102, starts and runs well, plenty of power, ignition is fine. Adjustments on the carb seem to need to be richer than I'm accustomed to seeing on this engine, and with idle steady not too lean, not too rich, on rapid acceleration there is a hesitation.not a bog as in too rich, but as in semi-starving on rapid demand. My experience tells me to get into it and tweak the main needle and lever, maybe the spring tension.anyone have any guesses or similar experience to share?
Lever position sets the height of the metering needle. Too high and the needle remains open. Too low and it does not open enough. So the lever height means very much, making things lean regardless of what you do. Depending on the carb you have, the correct pop off pressure could be anywhere from 15 to 32 psi so some experimenting might be in order. One of the resons Walbro sells different springs for their carbs. Typically an SDC 80 is in the area of 18-22 psi, but the Chinese carbs don't always follow true Walbro form.
Makes life more difficult than it needs to be. The Walbro service manual has the theory and how to test both lever height and pop off pressure. The issue is, I believe, that there is such a wide variation.
The manual itself says popoff pressures can be between 10 and 32 psi with no apparent performance differences (assuming a chain saw, leaf blower, or weed whacker, I think). I don't think they acknowledge that model aircraft engines have different sensitivity to variations, etc. I have read of others buying a bag of springs because they.do. vary so much.but as I've never gotten that deep into it, I don't have first hand knowledge about it. But - it seems that I shortly.will. You guys are getting the picture, The lever hieght can make a big difference and sometimes a small adjustment to it can be all that is needed, it regulates how far the inlet needle opens or lifts off its seat and how much volume of fuel is available at the needles.
The carbs and manuals for them are not designed for our application so after concept and theory of operation are understood, some experimentation is needed if a finer tune is necessary. What should also be understood is how the small fuel orfices near the throttle valve operate, the one on the engine side of the valve is the only one that is regulated by the low speed needle, the 2-4 orfices (depending on carb model) in front of the throttle valve are not and fuel is pulled through them when the valve is cracked open and low pressure forms behind the venturi.
The chainsaws, blowers, and whackers just need to idle and get to full throttle, high speed operation, we are trying to use the same carb in an application where we want the engine to produce consitantly increasing power throughout the whole RPM band. Walbro does have several different weight springs, you should be able to get some of them from a good outdoor equipment or saw shop.
Walbro Wj Carburetor Manual
Walbro carburetors are almost standard on most all two-cycle engines. Two-cycle engines require that oil is mixed with the gasoline fuel. Failure to mix the correct oil in the gasoline will result in permanent engine failure and damage. Adjustment of the carburetor may have to be performed on a periodic basis and most definitely after the simple device is rebuilt. Adjustment will not take long and the small screws may have to be 'tweaked' after the engine has warmed up and been running for a few minutes. Allow the engine to return to an idle operation by releasing the throttle. At idle the engine should be running smoothly.
Quickly depress the throttle again. If the engine hesitates open the 'lo' fuel screw to a quarter turn counterclockwise. Perform the release and depression of the throttle a few times. The engine should go from idle to full RPM in a smooth progression.
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Walbro Wj Carb Manuals
Honda crf50 service manual. If the engine pops heavily at idle, when coming down from a full throttle, the 'lo' fuel screw is delivering too much fuel. Turn the 'lo' screw in a clockwise direction using no more than quarter turn increments.