Anyone Tried Motorized Bicycles?

Discussion in 'Battle Scooters' started by Colorado CJ, Jun 4, 2013.

  1. Dirt Road Cowboy

    Dirt Road Cowboy Sometimes I'm A Jerk

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    My 4 stroke friction drive will go 18-22mph all day, and that's good enough for my mountain bike. As you said, it is an assist for when I don't feel like pedaling.

    A rear mount/friction drive can also be hidden behind some false touring bags to operate in stealth mode. :evil

    Those little gas tanks they come with won't get you very far either. I carry a couple of the 30 oz MSR fuel bottles for extra gas, but I want to set up something more permanent that runs direct to the engine.

    I do need to get my motorcycles going again though. I miss riding them. :cry
    Too much of "life" has been coming up lately.

    My CT90 frame looks at me every time I go into the workshop, just begging for the 140 Lifan engine to go in.

    I guess I need to just get busy! :1drink
    #41
  2. YamaGeek

    YamaGeek Ancient trailbike padwan

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    I think the big problem with the Chinese 2 stroke bike conversion kits is that the engines are old school, iron linered cylinders with a need for careful break-in treatment for the first few hundred miles.

    We've been using chrome cylinder 2 stroke engines for years that you can basically run nearly WOT straight out of the box, so that it's a bit unusual to have to consider a break-in period for a new small engine like this.


    I'd be using a smidgen more oil in the premix and trying to richen the jetting to keep it running cool.
    #42
  3. Motovista

    Motovista Parts is Parts

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    If you google Chinese "happy time" and "China doll", you don't get these results at all.
    #43
  4. Motovista

    Motovista Parts is Parts

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    The reason you need to break in a 2 Stroke still is that where new rings go past the ports, you have hard angle meeting hard angle, even on nikasil or chromed cylinders. Over the first few hours, this contact area wears smooth. That's where the rings usually break on a new engine if it's not broken in right. Chamfering the ports will help it break in better, and most high end cylinders, at least out of Italy, are finished by hand to a certain extent. But you still need to be easy on a new 2 Stroke top end.
    Suzuki did a study on 2 Strokes and found that they break in after about 4-5 hours.
    We always premix at 30-50 to one and use the oil injector for the first tank or two. And if I want a motor to last a long time, I let my wife, who's first question about a new bike is not, "how fast will that go?" ride it for a couple of days.
    #44
  5. JerryH

    JerryH Banned

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    "Rock Solid Engines has an optional Walbro kit for Happy Time/China Girl engines"

    This post is from a motorized bicycle forum. On all these forums, the cheap 2 stroke frame mount Chinese engine kits in either 48cc and 66cc (sometimes referred to as 80cc but displace only 66cc) are referred to as an HT (Happy Time) or China Doll/China Girl engine. These engines have many brand names, but all are the same design, which started out as a "Grubee" engine. They are extremely cheap, both in price and quality. Average life of one of these engines is under 1000 miles. They are a universal fit, and do not properly fit newer bikes with large diameter downtubes. They use a flimsy "rag joint" to attach the motor driven sprocket to the right side spokes in the rear wheel. It is very hard to get centered, and often comes loose. They use an even flimsier "tensioner" or "idler pulley" clamped to the chain stay to keep the motor chain from flopping around. Because the chainstay is at an angle to the rear sprocket, it is common for the chain to come off or break the pulley, get hung up on the bracket, and pull it into the spokes of the rear wheel. It happened to me. The tensioner bracket is so flimsy it can be easily bent with your hands.


    http://farm4.static.flickr.com/3416/3233093910_76ac9afda4_o.jpg This is a typical HT, Happy Time, China Girl bicycle engine kit. The rear drive sprocket is on the upper right, the "rag joint" mount is below and to the left of it, and the "tensioner" roller and bracket is to the left of that. The plastic pulley is about the same as what you would find on a sliding screen door. The metal bracket can be bent double with your hands, but will still lock up the rear wheel. You can usually get these kits for under $200 with free shipping. I consider them a death trap. These engines can reach up to 30 mph, and going down at that speed is not fun. And to make matters worse, people usually put these engines on a $70 Walmart bike with nothing but a rear coaster brake.
    #45
  6. Dezzie

    Dezzie Been here awhile

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    I just bought my first cruiser in the UK, reading up on everything I saw more folk fitting electric hubs in them, yes there pricey but ya can buy the kits from ebay a lot cheaper if Chinese made but some manufacturers are coming up with there own builds, I found this site and fell in love, the most stunning electric/pedal bikes I have ever seen and if I had the money there would be one in my bike shed now sharing space with my msx125!

    http://www.enorm-ebike.at/
    #46
  7. Motovista

    Motovista Parts is Parts

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    I googled "Rock Solid Happy Time China Girl," and none of the results were about bicycles. That's not a piston, Jerry.:rofl
    #47
  8. JerryH

    JerryH Banned

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