40 MPH Club

Discussion in 'Motorized Bicycle General Discussion' started by massdrive, Aug 10, 2014.

  1. massdrive

    massdrive New Member

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    After lots of mods, and months of adjusting and tuning I finally broke threw the 40 mph barrier... 43.5 mph. I was riding on Lake Mead Blvd. side by side with traffic and wasn't looking at the speedo so I didn't even know I broke threw until I got home and was checking the stats on my trusty Iron Horse bike computer. It tells me all kinds of info like date & time, air temperature, ride time, miles ridden, compass heading, average speed, average ride time, calories I didn't burn pedaling, and of course max top speed.
    dance1

    I'm running a heavily modified 66cc China engine with single speed direct drive and a 36t sprocket on an adaptor. I use Opti 2 oil mixed at 100:1. The bike and engine have over 800 miles on them. Next comes a shift kit and than I'm going hunting for 50 mph...
     

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  2. Davezilla

    Davezilla New Member

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    Congrats on breaking the 40 mph barrier!!

    I still need to get a smaller sprocket.. and some time to ride mine to see if it can get there...
     
  3. massdrive

    massdrive New Member

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    Thank you Dave. My Rattletrap gets there pretty fast...
     
  4. Nashville Kat

    Nashville Kat Active Member

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    What carb are you using?

    and what was the distance of the ride?
     
  5. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    I remember breaking 40mph on my stand-up scooter and getting a Mach certificate for it back in 2005-2006. I'll have to break it out and post a pic of it....was running a 47cc Tanaka 47R at the time on a BladeZ Moby scooter with lots of mods.

    I'll sign-up for that club when I can build a motorized bike that can reach that speed.....stay tuned ;)

    dnut
     
    #5 scotto-, Aug 11, 2014
    Last edited: Aug 11, 2014
  6. ajoh

    ajoh Member

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    well done on hitting your goal


    no big block engines scotto lol
     
  7. turnofftheradio

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    Congratulations Massdrive!
    Success is sweet, enjoy the ride.
     
  8. LR Jerry

    LR Jerry Active Member

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    Congrats on the speed. If you haven't already done so you should weld in some frame reinforcements. I like filling in any weight reduction cutouts on the frame. These cutouts are common around the rear wheel dropouts. This is a common place the seat and chain stays break lose.
     
  9. massdrive

    massdrive New Member

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    I'm using a Mukini VM18 and the ride yesterday was about 10 miles. I rang it out for about 100 yards before approaching a traffic light.
     
  10. massdrive

    massdrive New Member

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    Why do I believe that you left 40 mph in your dust a long time ago....?? lol
     
  11. massdrive

    massdrive New Member

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    Thank you thank you thank you very much...
     
  12. massdrive

    massdrive New Member

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    Thank you Jerry. I wish I would have reinforced the frame, but since it is now powder coated I don't think I'll be doing any welding on it anytime soon. Ya never know I may decide to tear it down again...lol
     
  13. Nopedaling

    Nopedaling New Member

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    This thread makes me happy! I have a completely stock 66cc chinagirl and I hit 40mph on flats with the 44t and stock nt carb, I can't wait to see how she goes with a high comp billet head and Dax carb with the 36t :D
     
  14. The_Aleman

    The_Aleman New Member

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    That's 9250RPM with a 26" wheel. Either your speedometer is way off or you're full of it. Either way, don't expect your chinagirl to live much longer.
     
  15. massdrive

    massdrive New Member

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    Thank you.... I was just going to write the same thing. Even with a modified china engine nowhere in this universe is 40mph possible on a 26" wheel with direct drive and a 44t sprocket. Well maybe down a steep hill with a 20mph tail wind...lol Even with a 36t sprocket a stock china engine doesn't have the hp to push the bike much over 30 mph

    Although I haven't been involved with MB's for very long I am a 57 year old gearhead with mad crazy skills and I worked hard for over a year and spent a good amount of money to get into the 40 mph club and I get annoyed when I see this and hear this from people. So I say to all put up or shut up!
    .flg.
     
  16. massdrive

    massdrive New Member

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    One more thing. My quest for speed is really a quest for a higher cruising speed with good reliability too. Cruising at 20 to 25 mph is good and this is mostly what I do. However there are times when I want to cruise at 35 mph and not kill my engine. There are also those times when some jerk off in a passing car says something rude to me and I just love the look on their face when I pass them... As I said before I have close to 1000 miles on my engine and it still runs great and I've never had a breakdown... not yet... I know it is coming though. When my China girl finally draws her last gasp I have a 99cc Predator waiting on a shelf in my workshop.
     
  17. The_Aleman

    The_Aleman New Member

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    The first time I hit 40 on a motorized bicycle was with my first build on it's second engine back in '07. I had a laser-cut adapter I designed that used the older-style large-bolt kit ragjoint, allowing me to bolt 110MM BCD sprockets to the ragjoint without removing it. I started with a 39T, ended up with a 34T. My top speed was 42MPH, which was ~7500RPM. That engine was on the very edge of survivability at that RPM, and it did eventually start knocking in the upper end. My 2nd build used yet another chinagirl and also attained 42MPH with the same sprocket.

    I blew up the first engine going 30 with the 44T. That one started knocking after a few runs over 6K RPM. Many chinagirls just shouldn't be run much over 6K if you want them to live for awhile. Some people get lucky with a great engine out of the box tho. My 3rd chinagirl was such an engine.

    All that said, I'm not going to believe over 9K RPM out of a stock engine. Only the very best rebuilt chinagirls like RSE and Arrow can do that and live.
     
  18. massdrive

    massdrive New Member

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    I have a second bike and it is basically a clone of my modified Rattletrap bike except the engine is almost stock. I cleaned up the header ID and matched it to the exhaust port and it came from Motovelo with a cut piston and drilled out wrist pin. I run a 40t on a hub adaptor and she tops out at a very scary 32 mph, and I need a good long stretch of road to get her there...
    she has no hill climbing ability at all, but I love her anyway.
     
  19. CranbrookKid

    CranbrookKid New Member

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    I got a rose326a motor that is stock besides the trimmed piston skirt. It hits 35 pretty quickly and the vibes are bearable at that speed although who knows how long it'll last with me pinning it at every straightaway lol.
     
  20. thatsdax

    thatsdax Member

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    I am running a new Build. A 38mm Stroker Balanced motor with GP full circle crank, with Port matched intake and exhaust, RT carb with 65 jet and Shark Air Box gold, Modified Factory Chrome Exhaust, Triad Plug, Slant head with 118 BMEP, Skirted piston, 26 inch rear wheel with 41T. Mix is 25:1 Valvoline 2 stroke oil. We hit 32mph using GPS and at 6000 feet with barely 10 miles on the motor. I know power will go up a lot as we put more miles on it. It pulls the hills well.. Actually accelerates up the hills in my area... So.. I know it will handle the 36T. I will update my top speed with the 36T.. Will I hit 40 ? Humm.. Not sure since we are down so much on power here in Colorado.. I also have 32T sprocket, but not sure the engine can handle it at such high altitudes here. At sea level.. Not a problem.. My Engine is down in power anywhere from 25-36 percent from sea level depending on our humidity which can be single digits on some days.. but anyway.. Having fun and my son is learning a lot about how to make an engine perform better.. Enjoy the ride.. :)
     
    #20 thatsdax, Aug 11, 2014
    Last edited: Aug 12, 2014

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