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RPM drop on take off.

in 2 Stroke Technical Questions 13 years ago

  • Re: RPM drop on take off.

    by » 13 years ago

    Kevin,

    Nick is right. all the fuel lines between the fuel pump and the carbs are under positive pressure. I would check the float arms to be sure that they aren't bent. You might also check the float valve needle and jet. If that jet gets partially clogged it can cause low levels in the carb bowl. There is a pin about 25 or 30mm that holds the float arms in place. You can pull this pin out and the float arm assembly will come right out. One end of this pin is knurled and you want to be sure to pull or push the pin out in the direction of the knurled end. With that pin out, the float valve will fall out in your hand. It has a rubber tip which can be worn or damaged. More likely though, the jet that the float valve sits in is partially clogged. Usually you can squirt some carb cleaner and/or compressed air through the jet from the needle side and solve the problem. If the clog is hard, a small piece of soft copper wire will clean it out.

    As for the fuel line, I use 20R6 or the high heat 20R7 fuel line. It's the same black fuel line thats in your car and it usually outlasts the car. If you want to go first class, get the high pressure fuel injection line. All of it is available at any auto parts house.

    Bill
      
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  • Re: RPM drop on take off.

    by » 12 years ago

    Just thought this may help people with the problem I had on the Blade. Although I worked through the fuel system ,cleaning carbs and changing fuel pipes ,filters ,etc ; I decided to change the fuel (again) although i had done it once already. I filled with Avgas/oil and nothing else ,and the engine performed great ,even through its Permit to Fly. I have now weaned it off slightly and am running on 40% Avgas and 60 % Unleaded with 50:1 oil and still experiencing no problems of power drops on take off. The work on the fuel system has obviously helped ,but it would seem the change in fuel has cured the problem.
    Kevin. :cheer:
      
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  • Re: RPM drop on take off.

    by » 12 years ago

    Very odd....must be a problem elswhere.

    Nick.
      
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  • Re: RPM drop on take off.

    by » 12 years ago

    It`s certainly an odd one , but I have flown several hours on this mixture without any problems. So here is hoping !!!!
    Kev.
      
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  • Re: RPM drop on take off.

    by » 12 years ago

    I was looking at some pictures of a Rotax 2 stroke that had be run on Avgas....the pistons did not look pretty...Cant remember where I saw it,

    Let us know how you go on with it.

    Nick
      
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