Cb350 K2 Carb Butterfly flap
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Thread: Cb350 K2 Carb Butterfly flap

  1. #1
    Junior Member stuzzy77's Avatar
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    Cb350 K2 Carb Butterfly flap

    The carb butterfly flaps with the spring and flap. One of mine is broken and I’m really struggling to find a replacement in the UK.
    How important is the spring flexi flap on these as I have sourced a new flap but not lower spring section.
    Attached Thumbnails Attached Thumbnails Cb350 K2 Carb Butterfly flap-e409a93d-972a-4c81-b7dc-a359ca406588_1559513394987.jpg  

  2. #2
    Senior Member Lefty's Avatar
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    That would be the choke, and I'd think it is designed to completely close. The suction from the engine opens the flap to let in enough air and enough suction left over to pull more fuel than normal for a cold start. Pretty good to have.

  3. #3
    Supporting Member Yendor's Avatar
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    I made my own from peices of Brass.
    You still have some of the parts I had pretty much nothing and made it all from scratch.

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    Bill H, Lefty, Pops and 1 others like this.
    1970 CB 350 CAFE - Current Project on the bench,
    1972 CB 350 K4 Red - Now a Happy Rider ! !
    1972 CB 350 K4 Green (My Sons) DONE - YES !,
    1st Bike 1970 SL 350 (Brought home in Parts - Trailer/Trunk/Back Seat - I miss that bike),
    2nd - Bike Kawasaki 750
    3rd - '73 XLCH 1000

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  5. #4
    Senior Member Bill H's Avatar
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    Great job!

    Bill

  6. #5
    Senior Member 83XLX's Avatar
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    Unless you live in a very cold climate and ride in the cold, I don't think the little spring-loaded flaps are really needed. The main plates should provide enough choke for most situations.
    ancientdad likes this.
    1969 Honda CL350
    1983 H-D XLX-61 Sportster

  7. #6
    Senior Member Lefty's Avatar
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    Nice work yendor!

  8. #7
    Junior Member stuzzy77's Avatar
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    Thanks all for the replies. Great finding out what it’s for.

  9. #8
    Supporting Member Yendor's Avatar
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    I would agree that the Flpas are not really needed.
    In fact I think you could simply make up a plate a drill a 1/2" hole and that would work fine.
    I have a video of the Plates I made on the bike running and in action. If I can figure out how to post a video I will do that.
    They only move when you really rev up the motor.
    And since the choke is just to get things up a started in cold weather there isn't really a need to rev it up.
    It only take about 30 seconds +/- in cold weather to warm up enough to drop off the choke and in normal FUN Temps for riding I usually don't even use it.
    1970 CB 350 CAFE - Current Project on the bench,
    1972 CB 350 K4 Red - Now a Happy Rider ! !
    1972 CB 350 K4 Green (My Sons) DONE - YES !,
    1st Bike 1970 SL 350 (Brought home in Parts - Trailer/Trunk/Back Seat - I miss that bike),
    2nd - Bike Kawasaki 750
    3rd - '73 XLCH 1000

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