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Carb sync for beginners

in 912 / 914 Technical Questions 10 years ago

  • Re: Carb sync for beginners

    by » 10 years ago

    The #7 mixture screw should be set at 1.5 turns out. The dry black soot they can develop at idle rpms is NORMAL. It can be slightly different for each user depending on how they operate their engine. The longer you idle at lowered rpms the more chance of some dry soot on a a plug or two. Do not adjust your carbs so the needle clips are unequal. If you live at higher elevation airports and always fly high the you could drop BOTH needle clips to the #2 position, but if you don't live or fly high I would leave them alone.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Carb sync for beginners

    by » 10 years ago

    Ok, I'll leave it. I bought r.o.a.n. movies access and movie told me the same, what local rotax dealer.
    My problem is carb control mechanism. Probably poor bowdens. This is the normal reason of unequal traveling of MAP when moving throttle. Next week I'll inspect my throttle lever, mixer and bowdens..
      
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  • Re: Carb sync for beginners

    by » 10 years ago

    In my earlier years the bain of my existence was poor throttle linkages. Either cables binding or metal linkages with play in them. I could never get the carbs synced and I'm kind of a perfectionist with carb sync so it drove me nuts. (Now I just take a handful of Valium, LOL). The first couple I thought it was the carb, but found out real quick that many throttle setups either use poor materials or have some play and the carbs never stay synced as well as others because the system never goes back to the exact throttle point and one carb is always off a tad from the other. Your only fix is to change the throttle setup or live with it.
    This for many is where the slightly rough engine comes from. Carbs not staying balanced after you sync them because the throttle system doesn't always allow one carb or both to go back to the exact same place every time.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: Carb sync for beginners

    by » 9 years ago

    Hi. I have new throttle system with gently, precission lines, works great. I still had problem witch swapping characteristic and much darker spark plugs on right carb. I tried to lean mixture on right carb for 1/4 turn and pressures of carbs are equal now in whole range of throttle. Engine runs much better but still after 20min of flight spark plugs of right carb are darker than on left. On left I have white spark plugs and on right dark brown.
    EGT temperatures on right cylinders are about 30*C higher and I can see that on there EGT's i have bigger difference between cylinders (40-90*C) in the same time on second pair I have about 30-40*C difference.

    I thinking about lean a little bit more right carb. What are you think about this?

    Carbs are after overhaul, spark plugs new with checked gaps.
    I have about 100RPM drop on L/R mags and no difference between L/R.
    Engine runs smooth when hot, tomorrow I'll check how about cold engine.
      
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  • Re: Carb sync for beginners

    by » 9 years ago

    As I found, spark plug shouldn't be white - it's too lean.
    So I think that I should make my dark brown side more lean and white side richer.
    Probably I read wrong my flydat. It shows highest temperatures on right side (dark plugs) but as I think higher EGT is on lean side (white plugs).

    It is correct way?
      
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