Top Speed

Discussion in 'Motorized Bicycle General Discussion' started by kevinkrg6, Aug 9, 2011.

  1. kevinkrg6

    kevinkrg6 New Member

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    I searched and couldn't find a thread like this, so I hope I can avoid scrutiny.

    Because of my low top speed and interest in getting the highest top speed possible (safety and engine longevity fanatics are going to love this thread), I wanted to see what others had as far as a final result for their setup.

    I was hoping everyone could post their Engine type,Sprocket size, aftermarket parts installed, and of course, their top speed.

    I will start.

    Skyhawk GT5, 40t Sprocket, Manic Mechanic Ported Intake, 25MPH
     
  2. 2door

    2door Moderator
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    Before we go too far, here's a word of caution.
    Threads about speed have, in the past, turned into arguments and promoted hard feelings with some members. The OP has asked a question that will get a lot of replys, some that might be hard to believe and cause strife.
    Keep the negative comments to a minimum, guys. Just remember our cardinal rule: Respect the other guy.
    Thanks.
    Tom
     
  3. biknut

    biknut Active Member

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    My 80cc has a 36T and will do a little over 35 mph, and I have a 50cc with a 40T and it will do about 30. These are top speeds though. A dependable cruising speed is about 5 mph less.
     
  4. Dave31

    Dave31 Moderator
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    Starfire 66cc with 36t Sprocket. Motor stock except for expansion pipe. 43mph on hot days. When the outside temp is cooler add another 3mph.

    In this video you can see me run wot with glance at speedo. From 8:55 to 9:40 or something....
    ‪A Ride On Motorized Bicycle‬‏ - YouTube

    With a little timing adjustment and carb tuning, different head I have reached 48-49mph. But motor really vibrates like crazy so I just run it stock.

    BTW..top speed is the same between expansion pipe or stock muffler. But snapper on bottom end with expansion pipe.
     
  5. biknut

    biknut Active Member

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    It's probably a good idea to mention tire size too, because that can make a pretty big difference in gearing too.

    My 80 has a 26x1.95 and the 50 has 26x2.125. The 26x125 is a lot fatter and bigger dia than the 26x1.95
     
  6. biknut

    biknut Active Member

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    That's exactly the same as my bike too. More bottom end, top speed is the same. What that probably means is the limiting factor isn't the exhaust.
     
  7. kevinkrg6

    kevinkrg6 New Member

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    Thanks 2door. Just hoping to find out some useful information. ;)
     
  8. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

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    As long as mine goes faster than that stupid dog down the street, I'll be more than happy.
     
  9. PerryP180

    PerryP180 New Member

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    Grubee GT5 Angle Fire, DAX RT Carb., 44 tooth sprocket, SBP fuel valve, #41 chain, my 240 pound body on it---- 25 mph wot screaming and vibrating. 20-22 mph comfortable cruise speed. Top end was the same with the CNS carb originally on it.
     
  10. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    A stock HT engine with a good pipe, intake & exaust port matching, properly jetted NT carb, & a 40T rear sprocket can get roughly 40MPH on a good day... (Depending on the weight of the rider.) ;)
     
  11. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    Non-Happy Time setup:

    Scooterguy center frame-mounted Tanaka 47R kart stock 2.8hp engine, plus
    Tanaka three-piece expansion pipe w/resonator and OEM muffler
    Shift kit w/pocket bike gearbox, 8mm chain and sprockets
    First gear - 37.09:1 gearing, like a HT 89-tooth rear sprocket
    Second gear - 28.36:1, like a HT 68-tooth sprocket
    Seventh gear - 16.36:1, like a 39-tooth sprocket
    Eighth gear - 12:1, like a 29-tooth HT rear sprocket

    Top speed without trying.....47.4 mphxct2
    Cruising speed.....35-40 mph
    100 mpg
    200lb rider
    40lbs of gear
    70lb bike
     
  12. rustycase

    rustycase Gutter Rider

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    This is embarrassing...

    Well run-in stock 48 skyhawk, cns @ #71 & 2nd notch, stock muffler, 44t, 26 x 1.95, 1000ft asl, 90F, 50% humidity, valvoline 2 cycle oil @ 40:1, level ground w/240lb ballast at a fumbling 20mph past the radar sign.

    This thing is NOT running right.
    just would NOT rev, but less stumbling at low and mid revs than before.
    WOT is worse.
    rc
     
  13. kevinkrg6

    kevinkrg6 New Member

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    Can I get a picture of this bike?
     
  14. Vistaman73

    Vistaman73 Chat Box Junkie

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    RAW 66cc, Dax RT Carb (Tuned), Manic Intake, Open Header Exhaust, Slant Head, NGK Plug, Upgraded Spark Cable, Slight Port, Generic Oil @ 32:1-40:1, 36T Sprocket, MTB Tires..............41.1MPH on the GPS (35.1 with a 44T Sprocket) Total Weight Rider and Bike: Pushing 300 lbs. (My Bike is HEAVY...) My bike is a massively framed 70's/80's Schwinn "ATB". I'm super proud of my bike... In fact, I got so bored with it running great, I broke down and started taking it apart, right it now I'm starting to rebuild the whole bike. If I'm not tinkerin' I ain't happy. :D

    -Vista
    P.S. PLEASE keep this thread friendly, I hate watching fights and I hope this doesn't turn into one.
     
  15. decoherence

    decoherence New Member

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    i like your documentation.
    does it actually sound like it is running bad?
    i was talking to a guy that weighs about 150# & was getting about that speed with the same specs you have. his sounded ok & he seemed to know how to work on it.
     
  16. happyvalley

    happyvalley New Member

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    Somewhere between 125 and 150 mpg, more if i pedal a lot ;-)
     
  17. decoherence

    decoherence New Member

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    mine
    grubee gt5, grubee "banana" expansion chamber.
    maniac mechanic intake, "speed" carb.
    harley sportster gas tank, oversized petcock.
    72:1 opti-2
    Micargi oversized "stealth" steel frame(very heavy)
    mountain bike front suspension.
    36T sprocket, 26" x 2.125"
    top speed is 30-32mph depending temp & humidity.

    i am pretty sure that my top speed is hindered my the banana chamber.
    the weld is slightly off centre.
    i will also try my cns carb & changing to 100:1.
     
  18. biknut

    biknut Active Member

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    I calculated the gearing on my Cadillac. Both the Cadillac and the Atomic BB top out about 7000 rpm. I'm guessing that's about it for a stock motor with no port work.

    20T engine
    82T clutch
    10T transmission sprocket
    36T rear wheel sprocket

    4.1 primary ratio
    3.6 final drive ratio
    14.76 overall drive ratio
    80.375 tire circumference

    RPM 1
    1000 5.2
    1200 6.2
    1400 7.2
    1600 8.3
    1800 9.3
    2000 10.4
    2200 11.4
    2400 12.4
    2600 13.5
    2800 14.5
    3000 15.5
    3200 16.6
    3400 17.6
    3600 18.6
    3800 19.7
    4000 20.7
    4200 21.7
    4400 22.8
    4600 23.8
    4800 24.9
    5000 25.9
    5200 26.9
    5400 28.0
    5600 29.0
    5800 30.0
    6000 31.1
    6200 32.1
    6400 33.1
    6600 34.2
    6800 35.2
    7000 36.2
    7200 37.3
    7400 38.3
    7600 39.4
    7800 40.4
    8000 41.4
     
  19. biknut

    biknut Active Member

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    This is the Atomic BB

    20....crank gear
    82....clutch gear

    10....counter shaft sprocket
    40....rear drive sprocket

    rear wheel circumference
    81.8"

    RPM
    1000 4.7
    1200 5.7
    1400 6.6
    1600 7.6
    1800 8.5
    2000 9.4
    2200 10.4
    2400 11.3
    2600 12.3
    2800 13.2
    3000 14.2
    3200 15.1
    3400 16.1
    3600 17.0
    3800 17.9
    4000 18.9
    4200 19.8
    4400 20.8
    4600 21.7
    4800 22.7
    5000 23.6
    5200 24.6
    5400 25.5
    5600 26.5
    5800 27.4
    6000 28.3
    6200 29.3
    6400 30.2
    6600 31.2
    6800 32.1
    7000 33.1
     
  20. biknut

    biknut Active Member

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    I've always been curious about what the maximum RPM is for a China Girl motor. When either of mine get up to about 7000 they sound like they're about to blow, but they never do. I'm guessing a mushroom cloud of broken parts at about 8000 rpm.
     

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