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  1. #41
    Airfield Ops BobH's Avatar
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    503 coils

    Quote Originally Posted by kawasakiinit View Post
    Already got it in bits mate and nothing obvious is wrong. Also the float valve is working as it should but sometimes they can stick intermittently I suppose

    kawasakiinit,

    Quick question, which plane is the engine on? The reason I ask is that on P+M trikes the round Mikuni pump has a brass bit on the back that the vacuum tube from the engine joins to. This has a really tiny hole in it. If that hole gets blocked it can cause problems. When running you should be able to see a very fine mist coming out of that tiny hole, but it's not very easy to see.

    I had this problem one year when I was trying to leave the Isle of Wight after Spamfield. The engine suddenly lost power at about 300ft and I had to keep pumping the throttle to get any power out of it while I did a very bumpy circuit before landing back at Sandown. Bill Brooks happened to be there and he came over for a look. There was nothing obviously wrong with the carb, but I cleaned it out anyway, then he suggested the tiny hole in the brass bit. Mine was partially blocked, so I cleaned that out as best I could, then reassembled everything. After that it flew without problems and got me back up to London Colney with the engine purring away smoothly behind me.

    Best regards,


  2. #42
    Captain kawasakiinit's Avatar
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    Yeah I noticed that hole bud .I'm gonna make sure its spotless when its back together. Cheers

    ps its on a flash 2 alpha mate ..
    Last edited by kawasakiinit; 22-05-17 at 22:38 PM. Reason: plane type


  3. #43
    Captain kawasakiinit's Avatar
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    ok so i got the pump service kit fitted and made sure everything was spotless on re assembly . i ran it up for 15 mins with full power and midrange combinations on ground without fault ,i then let it cool and did the same again without fault . one last thing i want to make sure is right is the fuel height in the float chamber .

    how high should the fuel be in my bing carb bowl on my 503 (single carb/single ignition) im gonna prime it with the primer bulb and check ,i know with the float bowl off it will be lower due to the lack of the main jet not displacing fuel in there but not sure how high is recommended.. the problem started after i swapped out the main jet and main needle(for the correct ones that should have been in there all along according to the manual) after cfi flew it on a check flight and told me my egts where way high, my logic tells me that the new jet is demanding more fuel from a fuel height that was prob ok with the smaller jet but now not so ?? it always did it at full throttle climbing which would also tilt the fuel in the bowl exaggerating the issue if its too low ..

    sorry for going on a bit

    cheers
    The more people I meet the more I love my cat..


  4. #44
    Co-Pilot oldbaldyman's Avatar
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    Ok to check the fuel level in the float bowl you must first run the engine for a few minutes then engine off and carefully remove the float bowl. Remove the 2 floats (without spilling any fuel) and hold the bowl level - the fuel should be 1/2" below the lip of the bowl (I have marked the 1/2" position by scribing the inside of the bowl lightly).
    Another good check is to turn the carb upside down and ensure the float arms are horizontal.
    You say you have swapped the needle - did you assemble the needle white plastic cup and O ring correctly and position the spring clip in the 'correct groove'?

    Another 'gotcha' is the rubber throttle cover gaiter (its not just for looks) - it seals the carb tower from water ingress which will freeze your carb and also from air which will cause the engine to run lean (and hot).

    Have you checked the choke plunger seal - well worth doing (replaciing).

    Finally, airscrew O ring these items are pence but any wear will give you a lean idle and dead band around 2500 3000 rpm.

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  6. #45
    Wannabe Pilot bingwing's Avatar
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    Quote Originally Posted by kawasakiinit View Post
    ok so i got the pump service kit fitted and made sure everything was spotless on re assembly . i ran it up for 15 mins with full power and midrange combinations on ground without fault ,i then let it cool and did the same again without fault . one last thing i want to make sure is right is the fuel height in the float chamber .
    Sounds like this could of been the problem kawa but altering the levels in the bowl would not solve the running temp! why change the main jet ? + needle from standard ?? are you trying to soop the engine beyond it's design limits like racing machines where you strip down after each race.

    Quote Originally Posted by kawasakiinit View Post
    it always did it at full throttle climbing which would also tilt the fuel in the bowl exaggerating the issue if its too low ..
    I do not know if you remember Mainair in the late 80's they made the first 532 Alpha that had to be section S to get it on the market! which involves flying the aircraft for a period of logged hours by a pilot from mainair! "1000 hrs rings a bell" It was Simon Kenyon (RIP) that was logging the hours for mainair! 'it was a incredible engine for power. It would climb easy 60* degree well beyond the required limit. On the day it happened he called into the field 'North West Microlights' to show us the machine! 'A Flash 2 Alpha 532' of which myself (QFI) and chief Graham Hobson (CFI) may be interested for sales 'etc. He left us for the last time!!

    All I can say we are all wizz kids at the end of the day while we are here!!

    http://www.pmaviation.co.uk/download...2_All%20Ai.PDF

    I don't know I think.


  7. #46
    Captain kawasakiinit's Avatar
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    Quote Originally Posted by oldbaldyman View Post
    Ok to check the fuel level in the float bowl you must first run the engine for a few minutes then engine off and carefully remove the float bowl. Remove the 2 floats (without spilling any fuel) and hold the bowl level - the fuel should be 1/2" below the lip of the bowl (I have marked the 1/2" position by scribing the inside of the bowl lightly).
    Another good check is to turn the carb upside down and ensure the float arms are horizontal.
    You say you have swapped the needle - did you assemble the needle white plastic cup and O ring correctly and position the spring clip in the 'correct groove'?

    Another 'gotcha' is the rubber throttle cover gaiter (its not just for looks) - it seals the carb tower from water ingress which will freeze your carb and also from air which will cause the engine to run lean (and hot).

    Have you checked the choke plunger seal - well worth doing (replaciing).

    Finally, airscrew O ring these items are pence but any wear will give you a lean idle and dead band around 2500 3000 rpm.

    cheers for that bud, yes i assembled it all correctly but will check again the seals etc . who would stock the small o ring for the air screw and the choke plunger seal?
    The more people I meet the more I love my cat..


  8. #47
    Captain kawasakiinit's Avatar
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    Quote Originally Posted by bingwing View Post
    Sounds like this could of been the problem kawa but altering the levels in the bowl would not solve the running temp! why change the main jet ? + needle from standard ?? are you trying to soop the engine beyond it's design limits like racing machines where you strip down after each race.




    I do not know if you remember Mainair in the late 80's they made the first 532 Alpha that had to be section S to get it on the market! which involves flying the aircraft for a period of logged hours by a pilot from mainair! "1000 hrs rings a bell" It was Simon Kenyon (RIP) that was logging the hours for mainair! 'it was a incredible engine for power. It would climb easy 60* degree well beyond the required limit. On the day it happened he called into the field 'North West Microlights' to show us the machine! 'A Flash 2 Alpha 532' of which myself (QFI) and chief Graham Hobson (CFI) may be interested for sales 'etc. He left us for the last time!!

    All I can say we are all wizz kids at the end of the day while we are here!!

    www.pmaviation.co.uk/download/upload_pdf/SB32_All%20Ai.PDF


    the needle was wrong to start with bud and the main jet i just thought it was running correctly at them temps. all i have done is return it to stock .. i would never try to run an engine outside its design envelope especially a 2 stroke ..
    The more people I meet the more I love my cat..


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