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Not sure on how to word this so hope I can explain it adequately! It’s probably simple but I’ve confused myself.

 

I understand that on first start of the day, it’s full choke with closed throttle. If the throttle is too open it can override the choke system. 

As the throttle lever hits the idle stops which are adjusted for idle rpm, at what idle rpm would a ULS be at risk of having the throttle ‘too open’ for the choke to activate? 

From reading, I also noticed that the choke had one of the holes enlarged in 2004 (my engine is 2002). Was this to help with starts? And is it worth doing the same on my engine?

Hope that makes sense and thanks for any help understanding the choke system. I did have a search but struggled to find the relevant topic.

 

 

  • Re: Understanding the “choke” system

    by » 5 years ago


    I would think you could test this by increasing rpm and then adding choke starting at lowest rpm in increments until choke has no effect on rpm.


  • Re: Understanding the “choke” system

    by » 5 years ago


    The key to remember is that the Rotax "Choke" is NOT a Choke in the common sense.

    The choke as you have known it, "Chokes" the Engine by restricting its airflow causing a Rich Fuel to Air Mixture.

    The Rotax "Enricher" (Choke) adds extra fuel to the normal Air intake volume causing a Rich Fuel to Air Mixture.

    Different approaches, Same Result!

     

    By opening the Throttle you are adding more air to the mix and canceling out the additional Fuel "Enrichment".

    If you are having trouble starting, you might start with the Throttle fully closed.

    Engage the starter for a few seconds and then open the throttle a 1/4 inch for just a moment and close it again.

    Repeat as needed for up to 10 seconds in total.

     


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.


    Thank you said by: James Llewellyn

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