60cc BMX with Vertical Shaft Friction Drive

Discussion in 'DIY Home Built Motorized Bicycle (non kit)' started by VlamBallas, Jun 4, 2011.

  1. VlamBallas

    VlamBallas New Member

    Joined:
    Jun 1, 2011
    Messages:
    25
    Likes Received:
    0
    Greetings all,
    Thought I would start a thread 'bout my new project. I have built quite a few motorcycles in the past, though have never attempted a Motorized Bicycle before.
    So, Just the other day I was lurking around a little scrapyard near my workplace, when I stumbled upon an old push lawnmower. The motor was still complete but not running. Minutes later, found a really old BMX, Looks like a child's bike, but I just thought that'd be sweet.
    [​IMG]
    With some cleaning and tuning got the engine running, runs like a dream, and has quite the rumble.
    Planning to mount the engine on top of the rear wheel,
    [​IMG]
    The rims & tyres in this pic are just temporary, needed something to put the bike on.

    Based my design on the vertical shaft drive like the ones built by vernon. With some small changes to the manner in which the drive roller engages the tyre sidewall. Using the rear brake lever and cable, from a small 50cc quad bike, to disengage, and some heavy springs to engage the motor.

    I know that a vertical shaft engine is not exactly the best option, but the engine and bike were free. (My budget is basically $0,00, with the exception of tyres)
    Any tips or tricks of trade are welcome!
     
  2. harlyhermansson

    harlyhermansson New Member

    Joined:
    Nov 7, 2010
    Messages:
    102
    Likes Received:
    0
    interesting build will be fun to se how you solv the hinges for that setup. and btw the tyre sidewall is qite thinn might be worth to chuse a drive roler that dosent eat the tire to bad. but im sure you will solve it.
     
  3. turkman

    turkman Member

    Joined:
    Nov 12, 2009
    Messages:
    221
    Likes Received:
    5
    Dude you have to put down the pipe
     
  4. VlamBallas

    VlamBallas New Member

    Joined:
    Jun 1, 2011
    Messages:
    25
    Likes Received:
    0
    Plan to use a rubber skateboard wheel, I reckon it will have the least impact on the sidewall? But tyres in this size are quite cheap,
    Will be making the lower part of the engine mount when I get to work tomorrow, Waiting for the wheels to get fixed up, the spokes where in a bad condition, before I can mount it to the bike.

    @turkman, What you mean put the pipe down?
     
  5. VlamBallas

    VlamBallas New Member

    Joined:
    Jun 1, 2011
    Messages:
    25
    Likes Received:
    0
    Heres what Im planning to do with the engine mount. Not including the lever that will pull the engine away from the wheel, or the springs that should pull it back into contact.
    [​IMG]
    (All credit due to vernon/retiredtinkerer)

    Oh, btw, My seatpost is jammed. That thing does not budge, damn. Wrecked a vice grip trying to get it to move. Out of ideas now. Anyone know how to fix this?
     
    #5 VlamBallas, Jun 5, 2011
    Last edited: Jun 5, 2011
  6. harlyhermansson

    harlyhermansson New Member

    Joined:
    Nov 7, 2010
    Messages:
    102
    Likes Received:
    0
    about the seat post.have you tried heating it up with a propane burner or simelar? because if you heat it up it will expand an when it shrinks it shuld com luse! looks god btw.
     
  7. cannonball2

    cannonball2 Well-Known Member

    Joined:
    Oct 28, 2010
    Messages:
    3,608
    Likes Received:
    103
    Check out the post on the Cheap and Easy roller. Would be real easy to make for the 7/8 lawnmower shaft. I have 250mi on mine now with very little wear to the tire or roller. I think this one would baby the side wall, plus it has good grip. Have been kicking around a vert. build myself. Had planed on using the ever plentiful and cheap 3.5 B&S. They are fairly compact and light. Have been kicking it around ever sice I saw a vert engine on youtube. Guy used something way too big like maybe 8hp. Bike was a bear, nothing stopped it but it skook it apart. Be watching with interest!
     
  8. wayne z

    wayne z New Member

    Joined:
    Dec 5, 2010
    Messages:
    1,746
    Likes Received:
    2
    I built one of those several years ago. I hinged it under the seat and let gravity hold it down,with a long cantilever handle up to the front, where I could push the lever down and hook it under the toptube between the seat and handlebars,to keep it disengaged from tire.

    I said rollers. I started with a single 45deg cone shaped steel roller on the motor. Laminated wood would prolly work instead. The cone shape does not run on the sidewall.
    Didn't do well cuz the wheel flexed away from the roller and slipped too much.
    I added a second cone shaped idler roller on the other side of the tire.

    It worked well, was very fast with the old 3.5 Briggs & Scrapiron, but the tire wore out quickly, like in 75 miles.

    Note: The standard push lawnmower engine has a very lightweight flywheel, there mostly for cooling fins and magnets and recoil starter. They rely on the blade attached to the crankshaft for most of the flywheel effect needed to run smoothly.
    Mine was hard to start(kickback dangerously,would jerk the handle outta my hand) and hard to idle until i replaced the flywheel with a cast iron one from an edger motor.
     
  9. cannonball2

    cannonball2 Well-Known Member

    Joined:
    Oct 28, 2010
    Messages:
    3,608
    Likes Received:
    103
    You are right about the flywheel Wayne, a good point. A flywheel from a horizontial engine is a must. The rubber roller is easy on the tire.
     
  10. VlamBallas

    VlamBallas New Member

    Joined:
    Jun 1, 2011
    Messages:
    25
    Likes Received:
    0
    "Mine was hard to start(kickback dangerously,would jerk the handle outta my hand)"
    That has happened, though not too often. And two blue fingernails later, I decided not to start it again without an engine mount.
    Though I dont really have trouble starting it, and it runs like a dream. I might have to switch to a heavier flywheel when the motor is under load? Not sure how it will perform then?

    Was looking at the idea of a 45degree roller, but just cant think of any cheap (aka FREE) material to make it from?

    @wayne z, how did the hinges handle the vibration? Or rather how did you hinge it? That would be a much easier way to go if I can manage the roller. Especially since im using the brake cable "clutch".
     
    #10 VlamBallas, Jun 6, 2011
    Last edited: Jun 6, 2011
  11. deacon

    deacon minor bike philosopher

    Joined:
    Jan 15, 2008
    Messages:
    8,117
    Likes Received:
    1
    That thing is all engine, truly a thing of beauty to a gear head.
     
  12. wayne z

    wayne z New Member

    Joined:
    Dec 5, 2010
    Messages:
    1,746
    Likes Received:
    2
    I used a 3" long piece of 3" channel iron bolted to the triangle between the seatpost and tire with a clamp plate underneath.

    The channeliron has two 3/8" holes in the tangs to take a 3/8 rod hinge pin.

    The motormount was a piece if 1/4" plate with tabs on the front for the hinge pin and a hole for the engine shaft. I think I used spacers between the engine and plate so the bottom of motor cleared the plate. I used 3/8" shaft collars to keep the hinge rod in place.

    I made a stub shaft for the idler roller with a threaded hole in the end, to bolt it to.the plate, opposite of the drive roller.

    No probs with the hinge at all. No springs are needed, gravity is all you need to hold the motor down.
     
  13. moonshiner

    moonshiner New Member

    Joined:
    Apr 23, 2011
    Messages:
    199
    Likes Received:
    0
    well that's different for sure , i can't wait to see it run ... .cs.
     
  14. VlamBallas

    VlamBallas New Member

    Joined:
    Jun 1, 2011
    Messages:
    25
    Likes Received:
    0
    Anyone have an idea of roughly how much pressure is needed from the roller to keep it from slipping on the tyre? My guess is 'bout 10 pounds, need to find some decent springs. Need ones that are strong enough to keep the drive engaged, but also weak enough so that the lever can disengage it when needed.

    Will definitly look into the gravity-45degree thing, will be able to switch over if I can find an appropriate roller though..

    Need some opinions on an aluminium roller? Could simply modify the head that kept the blade on. Grind it down, smooth it out, and file some small ridges 'bout every 2mm?
     
  15. NEAT TIMES

    NEAT TIMES New Member

    Joined:
    May 28, 2008
    Messages:
    1,964
    Likes Received:
    1
    This is an interesting thread

    Wayne & Cannonballs

    Could you post pic`s of mounts/drive rollers? Or did you do a build thread?

    Thanks, Ron
     
  16. cannonball2

    cannonball2 Well-Known Member

    Joined:
    Oct 28, 2010
    Messages:
    3,608
    Likes Received:
    103
    I havent done a vertical build yet, was just suggesting the homebuilt rubber roller. If you want to see that its in DIY Under cheap and easy roller. My two are working great, and Im on my way to a third build using one.
     
  17. Dan

    Dan Staff
    Staff Member

    Joined:
    May 25, 2008
    Messages:
    12,776
    Likes Received:
    97
    Lookin' awesome Vlam.

    Been thunking about this for a while. Vert. shaft lawn mower replacement engines are cheap here and low profile. The only thing I came up with for a roller(s) is a boat trailer roller cut in half. Rubber, 45* and a ton around on old junk trailers. Just a thought. Cannonball's would be perfect though. (dang, now I gotta rethink this, lol)

    Did you get the seat post out? I have used some penetrating oil and a pipe wrench. But any oil will help some.

    Great information about the fly wheel! I would never thought about that until struggling with it. Thanks Wayne.

    Great thread.
     
    #17 Dan, Jun 6, 2011
    Last edited: Jun 6, 2011
  18. VlamBallas

    VlamBallas New Member

    Joined:
    Jun 1, 2011
    Messages:
    25
    Likes Received:
    0
    Not yet, that post is still stuck. Ive tried pulling, banging, turning, And Heating like harley suggested. Not moving, next attempt will be with a serious pipe wrench and some oil.
    Seems that everything is stuck on this build, the aluminium head, that holds the blade, is also stuck on the shaft. Sure a bearing puller will be able to take it off though, I hope.

    And great idea, the boat roller, is. I am in the trailer business, so im sure there will be an old one laying around somewhere.

    Welded the main part of the engine mount today, Will be fitting it in a day or so, once I get my wheels back.
    [​IMG]
     
  19. NEAT TIMES

    NEAT TIMES New Member

    Joined:
    May 28, 2008
    Messages:
    1,964
    Likes Received:
    1
    Vlam

    you could also use heat with the pipe wrench. The seat post will be down in the frame. I have had some great luck with the "tv blaster" brand penatrating spray. Letting it soak overnight with a couple applications.

    Neat looking engine mount. Did you get a chance to look at cannonball2 diy
    friction roller. Maybe mod it for the tapered boat roller.

    Am wondering about side pressure buckling wheel. Good luck, have fun.

    Ron
     
  20. VlamBallas

    VlamBallas New Member

    Joined:
    Jun 1, 2011
    Messages:
    25
    Likes Received:
    0
    Yeah, checked out his roller, pretty shweet idea right there. But I dunno how I'm gonna mount it to the shaft? There is no thread or anything on there..

    An idler wheel on the other side will keep the wheel from buckling too much,
     

Share This Page