Vintage Miyata Road Bike - First Build

Discussion in 'Introduce Yourself' started by ccasey75, Feb 20, 2014.

  1. ccasey75

    ccasey75 New Member

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    Hello all - I saw one of these bicycle engine kits online and knew that I had to put one together. I had a couple of bikes in the garage, but this 1991 Miyata 914 SE was the only one that could accomodate the engine in the frame.
    _photo 0.jpg
    I ordered a cheap kit from eBay knowing that it would be ripe with problems and issues to fix (something I actually enjoy). I set up a work station in my garage with a couple of saw horses, and old door, and I built a wooden stand for the bike based on picute that I saw on one of these forums (KCVale I think...):
    _photo 1.jpg
    You can see that I swapped the drop-bars out for a 5" riser bar, added a dual-pull brake lever, and went from 700cX23 tires to 700cX28 tires (as big as will fit under the brakes). I also had to replace the bottom bracket with a wider setup to clear the engine housing and exhaust. I just can't bring myself to actuall use the rag-joint sprocket attachement to the spokes (since I have other options), so I researched hubs and options and ended up ordering a Grubee HD hub from piston bikes. I really enjoyed building a bicycle wheel from scratch for the first time. I ordered a rim and spokes cut/threaded to length from universal cycles. Here is the wheel I build when it was trued up and test fitted on the frame:
    _photo 3.jpg
    The dropouts on this frame are 126mm and the HD hub is ~130, but it still fits OK. The hub came with a 48 tooth sprocket (I would have prefered a 44), and I bought a freewheel sprocket for the pedal driven side. I ended up getting thigs initially fitted up with the engine mounting position raised using an offset mount/adapter on the front. My intention was to improve the clearance between the chainstay and the chain, but I still needed a tensioner. I threw together a spring chain tensioner:
    _photo 4.jpg
    I had real isses with the chain jamming in the drive sprocket cover with this higher engine mounting position. The front offset bracket allowed for too much side-to-side movement of the engine, which resulted in sprocket mis-alighment and chain jamming. I ended up dropping the engine mounting position back down into the frame and dumping the spring tensioner for a standard setup. This fixed the problem and the bike is up and running:
    _photo 5.jpg
    I am still running ~18:1 ratio of oil in the gas, and I am having quite a bit of oil being carried through the exhaust, so I am gradually cutting it back. I also think I am 4 stroking quite a bit and will have to lean out the fuel a bit. I am at ~3000' above sea level, so maybe that is enought elevation to require some adjustment. I may look at adjusting the main jet size.

    I have added a suspension seat post and a spedometer since the last picture. This has been a fun project. I am trying to take it easy during break-in, but I have pushed things up to ~26 mph top speed so far. I may swap to a 44 tooth rear sprocket eventually. Let me know if anyone has thoughts, comments, or suggestions.
     
    #1 ccasey75, Feb 20, 2014
    Last edited: Feb 20, 2014
  2. paul

    paul Active Member

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    Nice motorized bicycle casy! that is what it is all about is fun, fun to build and ride, great to have you with us. i will let one of the other members answer on the field elevation issue. i am not really sure
     
  3. GearNut

    GearNut Active Member

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    Nice build!
    I can't comment on the jetting issue other than I bet you will have to solder and drill the jet to a smaller size. I doubt that adjusting the needle clip position will be enough. The air certainly is thinner 3K feet up.

    Be careful of that chain tensioner. That particular style loves to eat rear wheels for lunch. Considering that you just built the wheel, that would be a travesty.

    Here are some threads to give you an idea:
    http://motorbicycling.com/showthread.php?t=2063
    http://motorbicycling.com/showthread.php?t=22279
    http://motorbicycling.com/showthread.php?t=24668
    http://motorbicycling.com/showpost.php?p=183782&postcount=4
     
  4. ccasey75

    ccasey75 New Member

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    GearNut - Thanks for the suggestion. I have been concerned about that tensioner. I picked up a piece of cold rolled strip and some rubber lined clamps this weekend. Here is my new tensioner about 75% complete:
    tensioner.JPG
    I ordered a new stem/quill so that I can move the handle bars up and back a bit. I am also having quite a bit of vibration in the handle bars. I am guessing that soft grips would help. I may also look at filling the handle bars with something moderately dense... Any ideas out there?
     
  5. CTripps

    CTripps Active Member

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    Welcome to the forum.

    Soft grips are good. Some members have filled thier handlebars with sand or lead shot to help with the vibration.. do a little searching and you should find plenty of ideas.
     
  6. Theon

    Theon New Member

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    A bit of solid steel bar a couple of inches long in the handle bar ends helps a little.
     

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