how to use the choke

Discussion in 'Motorized Bicycle General Discussion' started by Crysisfreak7, Jun 3, 2014.

  1. Crysisfreak7

    Crysisfreak7 New Member

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    if i run the bike for awhile and then bring the choke to half, i lose a lot of power and speed, how do i use the choke?
     
  2. CTripps

    CTripps Active Member

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    The choke is useful starting a cold engine sometimes.

    On a stock carb, I have found I never need the choke; set it wide open and they usually start right up. If you're using a performance carb then you may need to use the choke to start the engine. On my bike with the 'Speed NT' carb (red square cover) I often need the choke closed for the first clutch drop, then it can be opened up within 5-20 seconds depending on whether it's cool or warm weather.
     
  3. 2door

    2door Moderator
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    What engine do you have? We are assuming it is a Chinese 2 stroke because they are the most common.
    What carburetor do you have? If an NT or NT Speed, the lever down is 'choke off or open'. Lever up is 'choke on, or closed.

    After the engine starts and runs for a few moments the choke lever should be in the down position, choke off, from then on. If you have to run with the choke on or partially on, you have an air (vacuum) leak.

    Tom
     
    #3 2door, Jun 3, 2014
    Last edited: Jun 3, 2014
  4. greaser_monkey_87

    greaser_monkey_87 New Member

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    I picked up on two things you said. One was "when I run the choke for awhile". How long is awhile? Running with the choke open for too long will actually flood the engine. You should never need the choke for more than 15-20 seconds, and that's usually in cooler temperatures. In warmer temperatures, 5-10 seconds if at all. The other thing I picked up on was "bring the choke to half". A carb that is properly installed and sealed with no leaks or cracks anywhere should run smoothly with the choke all the way off (open). A carb that is tuned very lean may run better with some choke, but the NT carbs usually don't come lean stock. If you're in Death Valley or somewhere else way below sea level, the stock tuning might be a little lean due to the increased air pressure, but if you're at or above sea level, the stock tuning should definitely not be lean, so if you haven't leaned out your carb at all, then it should be able to run smoothly with no choke (once warmed up), provided that the carb is properly sealed to the intake and has no cracks. Remember like Tom said, when the lever is down the choke is open, and when it's up the choke is closed. You want to close the choke to let the engine warm up, then open it to let the engine run smoothly once warmed up.
     
  5. 2door

    2door Moderator
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    I think you meant the opposite. Running with the choke 'closed' will cause an over rich condition.

    Tom
     
  6. greaser_monkey_87

    greaser_monkey_87 New Member

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    Yes, that's what I meant lol.
     
  7. Crysisfreak7

    Crysisfreak7 New Member

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    looking inside the carb, and lifting the lever upward i see a little silver disc with a hole in it move infront of the air intake, i assume this is choke closed. does this mean that i should start the engine with choke closed, the puch the lever down to allow more air in?
     
  8. 2door

    2door Moderator
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    You are correct. The 'choke plate' is indeed the part you see. Lever up, the plate covers the inlet air opening in the carb. Lever down, the inlet is open.

    On a cold engine start it is sometimes beneficial to close the choke either partially or all the way. When the engine starts and after a few seconds the choke should be opened and left open thereafter. Usually you won't need to choke if the engine is warm.

    Using the choke makes for an over rich fuel to air mix that can assist starting a cold engine. Depending on carburetor tuning some engines don't need any choke to start, some like a little or a lot.

    A lot depends on your fuel/oil mix, outdoor air temperature, humidity, your altitude above sea level, etc. There are many factors that come into play on just how an engine starts and runs or its need for choke use.

    After some time you'll discover just what your engine needs for best starting. Experiment and it will tell you.
    Good luck.

    Tom
     
  9. allen standley

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    Gotta say thanks Tom. For the past 4 years to me your advice and instruction have been invaluable .... for all of us learning. Sincerely, Thanks again Tom.
     
  10. TakeiT

    TakeiT New Member

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    I usually never choke or prime mine.

    If the bike has been sitting for longer than 2 weeks (If im planning it, I shut off the fuel and drain the carb bowl), I turn on the fuel, give the gold button 5 pushes, then set the choke to half, and crank the motor. When she fires (you'll hear it 'pop') you release the choke fully and attempt to start it again, assuming it didnt stay running. Once it fires, immediately pull in the clutch and let it idle for about a minute (itlll be smokey) then rev it up a bit and you're good to go!

    If the motor has only been sitting for a short period of time, simply crank it until it fires, pull the clutch etc.

    In fact, I think a lot of people have questions about the 'proper' way to start their motor. This deserves a thread.
     
  11. 2door

    2door Moderator
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    TakeiT, The "gold button" you refer to is the 'tickler' or early primer. It isn't a pump. but actually pushes the float down, sinking it so an excess of fuel flows into the carburetor bowl that assures you have a fuel rich mixture for cold starts.

    Pushing that button doesn't pump fuel so there is no need to 'pump' it or push it multiple times. If you feel the need, just depress the button, hold it in for a few seconds, maybe three to five and that's all you'll need to do.

    If you take the NT carburetor apart and look at the end of the pin that is the "gold button" you'll see what it does when depressed. It isn't a pump.


    Thanks, Allen. I want to see new builders get the most fun and enjoyment from their bikes. Offering good solid, no nonsense advice is how I can do it here.

    Tom
     
  12. TakeiT

    TakeiT New Member

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    I thought it was, being that it didnt feel or look like a pump. Somewhere I heard elsewise.
     

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