Seriously CY29RC / CY27RC Engines

Discussion in 'General Questions' started by 210061741, Oct 29, 2009.

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  1. 210061741

    210061741 Guest

    I think i would like to put one of these on a bike.
    These motors are used for alot of things.

    The 29cc and the 27cc are compact 3+ HP motors.
    There are avaiable full dimensioned drawings for design purposes.

    Ok the clutch kicks in at 6000 rpm .....
    So obviously it will need geared down quite a bit.
    But the little things run to 18000 rpm.
    There are also Torque HP curves available too.

    They use these on gopeds with a 6T / 7T drive sprocket and a 98T driven sprocket.

    98 / 6 = 16.3 : 1 gear ratio.
    98 / 7 = 14 : 1 gear ratio.

    So lets look at the 14 : 1.

    6000 RPM / 14 = 428 RPM at 98 tooth sprocket
    15000 RPM / 14 = 1071 RPM at 98 tooth sprocket
    18000 RPM / 14 = 1285 RPM at 98 tooth sprocket

    Lets compare My current HT Rig.

    4.1:1 gear ratio.
    1000 take off rpm
    4500 max rpm

    1000 / 4.1 = 244 rpm at 10T drive
    4500 / 4.1 = 1097 rpm at 10T drive

    Well now that is interesting but makes sense.
    At a 14:1 ratio we would run the same drive speed at 15000 rpm but the starting range speed of 428 rpm whic is way too high.

    I would take a quick guess and say the starting speed would be around 15 mph.

    Thats alot of peddeling.

    The problem is if i reduce the gears higher I will loose the top end speed.
    That defeats the purpose.
    The honda uses a 3000 rpm clutch which lowers the starting speed alot.
    I beleive the CY29 idles at 4000 rpm so thoose 3000 rpm springs wouldnt work.

    Now i understand why the CVT comes into play.

    It Varies the gear reduction.
    I don't think the gen111 gearbox would work out.
    And i really don't think i want a CVT.

    I had hoped to use a jackshaft instead of a cvt for my gear reduction but that ain't gonna be easy.

    Any Ideas????????????

  2. AussieJester

    AussieJester Member

    You can buy custom CNC reduction units to step down in one or two stages...single stage start at $US220 double for the 2 stage...

    Check my link, they are for electric motors but no reason why you couldnt use them for ICE
    I have seen 20hp put through them so strength isnt an issue...

    My worklog has pics of the single stage...

    Last edited: Oct 29, 2009
  3. 210061741

    210061741 Guest

    Gear Reductions

    Very nice gear reduction i must say.

    But what i am thinking is the gear reduction alone will not produce the desired results.

    We would need a 14:1 reduction of the CY engine to = the same top speed as my HT.
    If the 98T sprocket was on the drive side of the motor mounted on a jackshaft and a 10T on the other side of the jackshaft driving a 36T rear sprocket

    At a 14:1 reduction the low end would be 428 rpm at 6000 rpm clutch engagement. The 428 rpm would be at the Jackshaft.
    36T at wheel / 10T at jackshaft = 3.6 to 1
    428 / 3.6 = 118.88 rpm of wheel.
    The tire has to travel 775.7 rotations to go 1 mile.
    So lets figure MPH.
    118.88 X 60 min = 7132.8 rotations per HR.
    7132.8 / 775.7 = 9.195 MPH.

    15000 / 14 = 1071 rpm
    1071 / 3.6 = 297.6 rpm of wheel
    297.6 X 60 min = 17857.14 rotations per hour
    17857.14 / 775.7 = 23.02 MPH with 10T drive and 36T driven.

    Boy thats not very promising.
    So figure we jackshafted into the geartrain so we could switch gears.

    Say we have a 7 or 8 speed rear freewheel.
    We save the 11T for peddeling.
    Next up say 13T

    13 / 10 = 1.3 : 1 ratio

    15000 / 14 = 1071 rpm
    1071 / 1.3 = 823.84 rpm of wheel
    823.84 X 60 min = 49430.77 rotations per hour
    49430.77 / 775.7 = 63.72 MPH with 10T drive and 13T driven.

    Now that is painfully fast.

    But what is the real advantage of the CY series Motors.
    For our purpose I'm not sure there is one.

    In other applications the advantage is the High Rpm available.

    We actually have to diminsh the rps by 14.

    In the end based off of the torque curve

    We would push about 1.618 Nm of torque starting at 8000 rpm and dropping at 12000 rpm.

    So in reality i don't see getting much better performance outta one.

    Maybe only the fact that the rpm increase so quickly.
    But the torque is fairly low.
    Meaning against resistance it would be slower.

    The HT has more Torque and we don't mess with the rpm so bad because the range is from 1000 to 4500 rpm.
    = 3500 rpm range VS 6000 to 18000 rpm range = 12000 rpm range.

    Higher Torque and Lower RPM is what i'm thinking will be what i want.

    Then i can actually use the torque properly.

    Anyone have an insight on this