forced air on CNS carb'-any opinions?

Discussion in 'Motorized Bicycle General Discussion' started by halfevil333, Jan 28, 2011.

  1. halfevil333

    halfevil333 New Member

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    hey guys ,
    I'm using one of the new CNS carbs, 2011 skyhawk, no tuned pipe yet, but that and perhaps making some sort of curved attachment to swing the air filter out and have it scoop more air (facing forward)...?

    as it stands now it seems I'm having better luck than most with this carb' but- I still get quite a bit of 4stroking, ran the best when I forgot to turn the fuel back on & in those moments before dying---SHE WANTED TO FLY!
    so my idea is that it seems i need to get much more air delivered to the a/f ratio, rather than simply jetting @a smaller size, and this way you could really take advantage of this carb's limitless adjustments?...

    anybody, anybody, anybody, Beuller?xct2
     
  2. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    You have to be going real fast for 'forced air' to have any real effect. It's best to just re-jet to a smaller jet.
     
  3. GearNut

    GearNut Active Member

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    Yeah, real fast as in at 60mph it just starts to have an effect on engine performance.
    I agree with Venice, you need to re-jet the carb.
     
  4. halfevil333

    halfevil333 New Member

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    well alrighty then, on to the next idea...
     
  5. Black_Moons

    Black_Moons New Member

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    Yea, you are running too rich if it goes better with fuel loss, Try rejeting, or using the stock carbs needle in the CNS. Im running a 0.73 jet with stock needle and it still is running a little lean at WOT but great everywhere else. (I Need a bigger jet or a diffrent needle taper)

    Also, id put the expansion pipe on ASAP, You have to retune your carb after you install a pipe, and the expansion pipe will add so much power it isent funny.
     
  6. LouieMCman

    LouieMCman Member

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    Here's an idea that I had from your question. This picture is of a project I finished last year that I spun the fan shroud upside down and routed the air through the front frame tube and it blows cooling air onto the front of the motor cylinder while sitting still for constant cooling. What if I reduced the air tube down from 3" to 1 1/2" to increase flow and tube up to the intake of the carb. Maybe use a bypass valve while idling and close the valve when RPM's come up and have a "blown" motor?
    Any comments on that???
     

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  7. soup325

    soup325 New Member

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    Get a 2 stroke leaf blower and mount to the intake of the bike engine. With the leaf blower providing a supercharger "EFFECT". Abit more gas through the carb, Easy as forced induction setup.
     
  8. BarelyAWake

    BarelyAWake New Member

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    Aside from the difficulties inherent with supercharging any two stroke (blow through) and those of attempting to pressurize a gravity fed carb (pressurization in 'charged systems usually takes place after the carb) ... the leaf blower idea is an almost classic example of diminishing returns - you'd be expending more power than would be gained.

    As an example, should even the above issues not effect the outcome - you'd still get far more a gain from that two stroke leaf blower engine if you didn't attach it to the carb and just rack mounted it as a supplementary drive engine by removing the fan & adding gear reduction & a chain/belt w/e - or by simply using a larger engine, one that was equal in displacement to the original engine and the leaf blower combined.

    While folks have 'charged two strokes, with displacements & power outputs this small it's a tricky business - the in frame Chinese two strokes are particularly poor candidates given their primitive design and comparatively low power... there's also the question of quality, such as bearings & head construction - I'm not sayin' don't try it as experimentation is great, jus' sayin' don't hold yer breath & if ya really wanna get into forced induction systems - ya might wanna try it on something with valves ;)

    Here's a link to some babble regarding such, including information on turbos almost small enough & a potential supercharger supplier (mebbe)... ofc it's a lil buried in a four stroke thread but w/e lol http://motorbicycling.com/f37/alternate-4-stroke-engine-list-19630-4.html#post223648
     
  9. bairdco

    bairdco a guy who makes cool bikes

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    my newest bike has a 16mm Mikuni and the barrel's reversed so the carb's in the front.

    this would suck in more air, as it's forced in just by riding it.

    my previous bike was the same way, but using a stock NT carb.

    there was a lot of discussion (more like a lot of hoping) that it would have a "ram air" effect.

    with the air filter off the NT carb there was no difference at all.

    on the mikuni bike, it rode horribly without an air filter, and just by putting it on it smoothed it right out and it rides great.

    i think modifying a stock filter to make it breath better enhances the performance a little bit, but making an actual "scoop" or any other kinda forced air is either gonna hurt performance, or make no difference at all.

    that being said, i only know what works on the bikes i have. i never tried to make a scoop, so like barely awake said, don't let this stop you from experimenting.

    also, in order to really know if it works, you need a well tuned engine to begin with. it's doubtful that forced induction would fix any problems you're already having.
     
  10. LouieMCman

    LouieMCman Member

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    Well let's talk 4 STROKES. I only use big, old, cast iron, four strokes (or what ever I can find cheap). Air intake is a velocity stack now, shouldn't be to hard to modify that. I have no experience with any of this but I already have an air source that I think I can reduce down for more velocity. I just don't know about motor air flow values enough to know what velocity is needed to boost performance. Guess I'll do some surfing...
     
  11. buzbikebklyn1

    buzbikebklyn1 New Member

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    Forced air induction on a 66cc china doll?
    The blower would be better than the engine!
    "LOOK AT THE BLOWER MAX! THE BLOWER"-
    "suck on that bronze!"
    Mad Max, 1979
    lol
    BBB
    [​IMG]
     
    #11 buzbikebklyn1, Jan 31, 2011
    Last edited: Jan 31, 2011

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