Scooter/bike hybrid

Discussion in 'Friction Drive' started by capturedbyrobots, Feb 11, 2008.

  1. Hey guys,
    I'm finally getting started on my motorized bike project.

    a GT Aggressor (I'm sooo aggressive... :???: )

    Motor: I'm using a Tanaka PF-4000 that I totally redid,
    making about double the power of stock.
    (pipe, lowered cylinder, porting, modding and stuffing of cases, bigger carb,
    no rev limiter mod) Est about 4 HP.
    I'll post picts of the mods if anyone wants to do them.
    It's pretty easy to do.
    Drive components: I'm using the rear end of a Boxer FS-1 motorized scooter
    (spindle drive, with gas tank mounted on the opposite side
    as the clutch assembly)

    This is almost going to be a bolt on job to my bike.
    I just have to mount the rear assembly to the seat post
    (I have the remnants of one of those "trail a bikes"
    so the linkage is almost made)

    The original spindle on the scooter was a .850
    and it pulled hard with it. I just took some skateboard wheels, and drilled them out to fit on the old spindle.
    I'm going to use set screws in the beginning , and epoxy them on to the shaft once I'm satisfied with their size and gripping ability.

    I'm pretty psyched about the project, I figure it will be ready to run by the end of the week.

    My only real question is how large of a spindle I should do.
    The wheels right now are about 1.6 inches.
    I can shave them down easily with a grinder,
    so I'll try it like it is first.

    What size spindles do most of you folks use?

    I had a feeling that around 1.25+ would be fine... but I'll
    try the large size first.
    I'm looking for speeds about 35ish

    Here's a shot of the rear without motor or gas tank....

    Attached Files:

  2. If the spindle seems too large (no power too fast) then you can always enlarge the drive that gonna be belt drive?
    I can't wait to see this thing.
  3. Nope, it's spindle drive,
    or as I see on this forum "scrubber"drive.

    It should be fun!
  4. uncle_punk13

    uncle_punk13 Guest

    With my tecumseh 49 cc Island Hopper, 1.5"-2.00" inch diameter drive roller I hit about 25-30. When I had a 1.0" driver I was hitting close to 35 but had very little torque for the hills around these parts, that's why I put the old skateboard wheel on, easier on the tires and the larger diameter gave me better torque... I'd think that with your engine mods and such you may find that where you're at right now with your drive roller is about where you want to be. I dig what you're doing with this set-up so please keep us posted with the details and pic.s
  5. Alaskavan

    Alaskavan Guest

    I agree with Rif. I've been using a 1.5" roller, and 2.3 hp moves it along pretty well. You should be right in the ballpark.
  6. I'm confused...
    From some of your posts it sounds like ya'll are saying that a smaller
    drive roller (scrubber) makes you go faster?

    That doesn't make sense to me.
    In my world of gopeds, the larger the roller, the faster the top speed, but less acceleration.
    Isn't that right?

  7. Alaskavan

    Alaskavan Guest

    Larger = faster. Smaller = stronger.
  8. That's what I thought.

    Those two posts I quoted seemed counter intuitive.
  9. dbigkahunna

    dbigkahunna Guest

  10. Dockspa1

    Dockspa1 Guest

    It's just like your two sprockets on you single speed bicycle. Bigger back, more torque smaller front, more torque. Smaller Back , more speed, bigger front more speed.
    Did I say that right? Ya, I think so.
  11. I'm well on the way to being ready for testing.

    This is mostly a mock up for now.
    Everything is welded and drilled,
    but I have NO fittings.... I used them all on my bots, or extra for the bots...

    So, a trip to the hardware store tomorrow should get me done.

    I mounted a gas tank, hooked the rear motor assembly
    to the seat post with that trail a bike hookup.
    got 2 side mounts ready for fittings,

    Then , all there is left is to run throttle and kill up to the handlebars,
    and paint it up.

    Hope you like...

    Oh, BTW......
    I know the exhaust shouldn't be over the tire, and I'll be
    bending or cutting and welding the tuned pipe
    to kick out exhaust more to the side.
    If oil drips onto the tire, that would be bad for a friction drive setup.
  12. srdavo

    srdavo Active Member

    Looking good. :cool:

    keep us posted!!
  13. Alaskavan

    Alaskavan Guest

    Cool. Good work. I bet she'll run good too.
  14. Do you guys think I should run the rear stabilizing
    bars off the axle nuts, or will those little threaded tab areas be ok?

    They will mostly be to stop the motor from jumping up and down

    I'm wondering if I should use something instead like a spring system
    or pull the motor spindle assembly against the wheel....
  15. Hive

    Hive Guest

    One Last Item

    Ejection seat?

    Gotta love it!

    Keep us posted.

    Robots rule!
  16. Alaskavan

    Alaskavan Guest

    The "little threaded tab areas" are what's used to stabilize the rack on a Staton kit. I have managed to break a stabilizer bar, but have had no problem with the connection to the frame. I only ordered one stabilizer bar with my kit, and have installed a chain and turnbuckle on the other side. It works well. I didn't use a spring. I don't want the engine to be able to bounce, no matter how bad I abuse it. There's a thread around somewhere that shows how I beefed up stabilization (I ride very rough roads, and go off-road sometimes).
  17. Ok, well I did the turnbuckle thing,
    and tried it today.
    It works pretty good, it would be much better if
    I didn't live in very hilly country (San Francisco)
    In a flat area, it would be awesome.

    The 1.6 scrubber can pull me up the steep hill, but it drags pretty bad
    because it never gets to it's power band
    so I need to grind the spindle smaller, or try a higher rpm engaging
    clutch spring.

    I think maybe I'll take it down to about 1.4 and
    see how it does. If it still has no power, I'll go down more.
    I also need to get a smooth strong tire for the back.
    Mine is knobby....
    Any particular tires that are better that you guys suggest?
  18. Oh, I forgot to mention,
    I burned my leg on that darn pipe.
    I have to get some pipe wrap.

    As well, I am mostly a "stand up goped"
    kind of guy.
    It feels so strange to sit while riding.
    My seat is buzzing like crazy. Has anyone here done any
    DIY seat vibration dampener shocks?

    Here's shots of the rear before testing.
  19. Alaskavan

    Alaskavan Guest

    I'm switching to a 1.25" roller to get more bottom end and better hill climbing on my Trek. I tried Armadillo tires, but the steel friction roller I use ate them up. That might not be a problem with the skateboard wheels. I switched to City Slicks, and am happy with them.
    Yesterday I ordered a shock absorber seatpost from Bike Nashbar:
    I haven't heard of anyone making their own.
  20. I might go that low too.
    Here's a question.
    If I were to make my spindle assembly arced,
    so it followed the contour of the new slicker tire,
    where would I measure it to figure out the correct size?
    I'm assuming the middle, yes?

    Oh, and I will be doing/getting a seat post like that.
    Please post whether it just work for bumps, or
    if it works well for vibration too.....
    Last edited: Feb 15, 2008