Pocket Bike Engine Project 3 (V Belt)

Discussion in 'Photos & Bicycle Builds' started by lowracer, Oct 18, 2011.

  1. lowracer

    lowracer Member

    This bike was most recently setup as a DIY rear rack friction drive. I didnt care for the friction drive w/ the high powered engine (bad tire wear) & changed it to a more efficient V-Belt drivetrain. I mounting this pocket bike engine on a lightweight, strong, aluminum rear rack using 1/4" aluminum stock & some 1/2" thick rubber skateboard riser pads as motor mounts to absorb vibration. I'll probably need to flip the handlebars upside down to get more weight onto the front wheel for handling purposes. Here are some pics of the mostly completed project. Check out the cable connection I made using a brass spoke nipple & some silver/lead solder. Instead of having to solder a new end to fit into the throttle slide, I simply cut the too short 42" cable I had, cut a new brake cable to fit into the brake lever throttle controller & soldered the two cut ends into the brass spoke nipple. Works great.
    -Lowracer-
     

    Attached Files:

    Last edited: Oct 18, 2011

  2. HeadSmess

    HeadSmess Well-Known Member

    that lil pulley with almost no wrap doesnt slip? even when soaking wet?

    id personally use an idler to get some more wrap or rub some violin bow rosin on the belt. :)

    otherwise looks good ;)
     
  3. lowracer

    lowracer Member

    HeadSmess,
    The belt doesn't slip.
    I have run a skateboard wheel tensioner in the past on a few of my V-Belt drive bikes, but mainly to take up excess belt & not for slippage. I do use the AX version of v-belt which is notched to allow for smaller pulley wrap angles & perhaps why I dont get any slippage.
    I dont ride in the rain, so I can't answer the soaking wet question.
    -Lowracer-
     
  4. blue 48

    blue 48 Member

    how do these go compared to the ht style engines?
    what size are they?
     
  5. professor

    professor Active Member

    Nice job Lowracer!
     
  6. lowracer

    lowracer Member

    blue 48,
    The pocketbike engine I have is 49cc . I don't know anything about the HT 1st hand since I have never owned one. From what I read, they HT's aren't high performance engines & cant rev high. I can rev 10-11k rpm's effortlessly (have a rpm meter hooked up to bike) & can hit speeds over 50mph if I want to. When I ride civil, I get approx 150mpg's (did a test). I have 2 bikes now with the same pocket bike engines on them & bought another one (on the way).
    I'm hooked.
    -Lowracer-
     
  7. blue 48

    blue 48 Member

    ok im sold the hts never let me down (one of which has about 15000 kms on it and still going well) but i like the mid frame mounting and chain drive so thatll be the issue ill have to tackle which wont be too bad
     
  8. lowracer

    lowracer Member

    blue 48,
    I'm surprised there aren't more of these engines being done in-frame since they are fairly narrow, can be bolted down onto an engine mount using the bottom mounting holes, & run strong for only $129 w/free shipping on eBay with a clutch driver 6T pinion. I'm thinking by using a seattube mounted jackshaft setup similar to a Sick Bike Parts shift kit, this driveline would be awesome.
    -Lowracer-
     
    Last edited: Oct 21, 2011
  9. lowracer

    lowracer Member

    I've been having expansion chamber withdrawal syndrome (ECWS) since putting on the DAX canister muffler. The little can kills the power output of the 2 stroke engne in a big way & though I thought a little de-tuning would be a good thing for a no-suspension bike, I was wrong.
    I had to do quite a bit of re-engineering to get the chamber onto this rig. The engine mounts had to be moved a few inches out & required a full day of re-work.
    Got it done today & I like the power...
    I also flipped the handlebars, pushed the seat forward, & dropped the seat way down for center of gravity & handling.
    Also added the skateboard wheel belt guide/tensioner.
    -Lowracer-
     

    Attached Files:

  10. bideronit13

    bideronit13 Member

    Does it have back breaks?
     
  11. lowracer

    lowracer Member

    bideronit13,
    No back brakes.
    The engine does a fair bit of engine braking before the clutch disengages the drum. Most weight goes to the front wheel under braking anyhow & the v-brakes out front are well set-up & strong.
    -Lowracer-
     
  12. bideronit13

    bideronit13 Member

    Pretty cool engineering there.
     
  13. lowracer

    lowracer Member

    Thank you.
    I like the engine on the front wheel more for handling, but I like the engine on the rear more for noise & handlebar vibration. Always a tradeoff...
    -Lowracer-
     
  14. bideronit13

    bideronit13 Member

    I never tried it but could you have a 3 piece crank freewheel in the front with 26" beach cruiser coaster breaks?
     
  15. 5-7HEAVEN

    5-7HEAVEN Member

    The crank would freewheel; you would not be able to activate the coaster brake.:detective:
     
  16. lowracer

    lowracer Member

    Coaster brakes are good for cheapy kid bikes but I haven't heard anything good about them for real bike applications?
    I heard there is a company coming out with a 'better mousetrap' coaster brake.
    -Lowracer-
     
  17. HeadSmess

    HeadSmess Well-Known Member

    how about adapting the band brakes from say a kids electric scooter to fit on the end of the engine pulley? use the driveline!

    think about the safety break on a chainsaw...

    its only the rear... doesnt need to be terribly powerful... more effort than its worth? im in the same boat and just dont have any :)

    coaster brakes are good on the ol' bmx...let you ride backwards without having to pedal backwards :D

    meh. theyve been around since the beginning in various guises... other than a bendix 2 speed theyre all relatively much the same... i always loved cooking them, holding them on slightly so theyd heat up :) got one to go blue and you could light the smoke coming from it :)

    oooh! hows about magnetic breaking on the pulley! a dc motor(generator) switched to a big low value resistor... breaking energy dissipates through the resistor. they do it on busses... :thinking:
     
  18. lowracer

    lowracer Member

    HeadSmess,
    I really dont think the rear brake is necessary on my drive type. When I let off the gas, the engine braking gets the speed down before I ever need to apply the front brake. In emergency slowdown maneuvers, the front v-brake is very powerful. I got the seating position low enough now that I wont go flying over the handlebars when I grab a handful of brake.
    -Lowracer-
     
  19. DeeDee

    DeeDee Guest

    Hello, I am very new to message boards. Thanks for posting this amazing idea.

    I just bought a folding bike with 20 inch wheels. Is there anything preventing me from scaling down the sizes of everything a bit?

    Also, if you put a how-to video on You tube, it would be wild success!

    Thanks again!
     
  20. David Bogle

    David Bogle Member

    What are you using for the large pulley on the rear wheel?
     
Loading...