Looking Low Weight Engine Kit

Discussion in 'Motorized Bicycle General Discussion' started by Michael1, Sep 22, 2012.

  1. Michael1

    Michael1 New Member

    Joined:
    Sep 22, 2012
    Messages:
    5
    Likes Received:
    0
    I would like to build a motorized bicycle (probably a mountain bike, but maybe a road bike) with a low weight engine, so the bike is light enough to pedal for exercise and offroad trails if I go with a mountain bike (i.e. not move at a crawl), and then motor back home (on the street). I am looking for the engine to give me some extra range.

    However, I'm not finding any information on the weight of these kits. The manufacturers seem to omit it (or hide it pretty well). I am also looking for something very reliable, low maintenance, and reasonbly quiet. In other words, I'd rather pay more for good quality, than fix it all the time.

    Any suggestions?

    Michael
     
  2. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

    Joined:
    Jan 8, 2008
    Messages:
    11,529
    Likes Received:
    2
    A small friction drive of 25-35cc would be perfect for your purpose.
     
  3. Matricon

    Matricon New Member

    Joined:
    Jul 18, 2012
    Messages:
    51
    Likes Received:
    0
    "Don Grubee says: The extra engine weight is hardly noticeable""Total wt. is 24 to 27 lbs."
    Right off the gasbike website for a 66cc 2 stroke kit.
     
  4. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

    Joined:
    Jan 8, 2008
    Messages:
    11,529
    Likes Received:
    2
    Yes, because it's more like 16 lbs, not 24-27 lbs.
    The engine alone is about 12 lbs. Then add the sprocket/chain, pipe and tank.
     
  5. tooljunkie

    tooljunkie Member

    Joined:
    Apr 4, 2012
    Messages:
    663
    Likes Received:
    0
    shipping weight on my 48 cc engine was 27 lbs.
    thats the whole kit.
     
  6. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

    Joined:
    Feb 6, 2010
    Messages:
    2,787
    Likes Received:
    1
    ...And then I have some days where it feels more like an extra 50 pounds. But then I go have some more coffee and I'm good. :)
     
  7. wheelbender6

    wheelbender6 Active Member

    Joined:
    Sep 4, 2008
    Messages:
    3,816
    Likes Received:
    10
    If you want to pedal a lot without engine assist, I would get a friction drive kit like the Bumblebeebolton.com. You can lift the engine roller off your tire without dismounting, eliminating drag.
    Thatsdax kits are sturdier but requre you to dismount to lift the drive roller off the tire.
    Pedalling a chain driven motorbike without assist will always involve some drag from the clutch unless
    you have a jackshaft/shift kit or a hybriped freewheeling rear sprocket.
    There are many choices for the pedaler.
     
  8. Michael1

    Michael1 New Member

    Joined:
    Sep 22, 2012
    Messages:
    5
    Likes Received:
    0
    Thanks for the help. That gives me a better idea.

    Michael
     
    #8 Michael1, Sep 24, 2012
    Last edited: Sep 24, 2012
  9. 2stroker

    2stroker New Member

    Joined:
    Apr 29, 2012
    Messages:
    168
    Likes Received:
    0
    Sounds like your looking for a bumblebeebolton...they give you all the info on the engine..i think it wreighs only 10 or 12 pounds..no clutch.just make sure you have your tension ajusted just right on the drive wheel..they can be touchy but when you get the feel of it..its one of he most reliable kits..i used to ride my everyday..if your looking for reliablity go with a friction kit..there much more reliable..theres a couple different kits..google friction drive kit..
     
  10. Nashville Kat

    Nashville Kat Active Member

    Joined:
    Apr 20, 2009
    Messages:
    1,428
    Likes Received:
    1
    My two builds so far have been about pedal-ability and light weightness.

    The four largest gains I think one can make with the China Girl kits- if you chose that- are:

    1. Eliminate the chain tensioner- I use a cruiser frame with pretty wide rear seat stay clearance- unfortunately i think a mountain bike may be a bit harder to get rid of the tensioner- but I've never tried

    2. Use a 415 Trike/ Industrial chain- only about HALF the weight of a standard kit chain- and ROLLS BETTER too with smaller plates- helps BOTH the motor and for peddlin.

    3. Use a smaller alloy motor sprocket
    The smaller the motor sprocket- the less weight it is and the less links the chain is- when you use a 36 or 34 sprock with NO tensioner, you can take out iNCHES of motor chain links. Depending on your riding style and the bike- so light narrow rolling wheels and tires are what I like.

    Outside of the motor the heaviest pieces are the tensioner (gone), the motor chained (halved), and the motor sprock and rag joint- (less than halved while still ragged and way less than halved directly bolted to the hub with titanium)

    4. Use a smaller tank- the smaller of the two sizes is only a slight dif empty, but the weight of gas really adds up fast- depending on how far you ride and how easily you can get gas. Mc Donalds is tried and true for that!

    Another thing- slightly more cost- but don't discount it- TITANIUM BOLTS-

    You'd be surprised how many bolts you can replace in a motor- but you may spend another 40 or 50 dollars to do it all- still they are really clean looking allen bolts that reduce the need for a lot of screwdrivers Also titanium on rag joint/ motor sproket bolts- I have a build with a 34 alloy sprock bolted directly to a high flange flip flop hub with small 5 mm TITANIUM bolts- The RAG JOINT is TOTALLY eliminated.
    It's a 700c wheel that feels like a featherweight road bike wheel but still 36 spokes and about a 1 1/4 inch profile worth of rubber.

    I'm not sure what the weight of my kits are under the stock weight- but it's a considerable chunk- and I've generally yet only replaced the clutch and cover bolts with titanium- two motors I think cost about 20 dollars so far

    good luck
     

    Attached Files:

    • b.jpg
      b.jpg
      File size:
      308.4 KB
      Views:
      30
    • b2.jpg
      b2.jpg
      File size:
      305.9 KB
      Views:
      33
    #10 Nashville Kat, Oct 6, 2012
    Last edited: Oct 6, 2012
  11. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    A lot will depend on the bike you choose and how it's outfitted. My 66cc china girl added about 25 lbs to the bike. Overall, according to the shipping scale at work my beast weighs in at 84 lbs (with a half-tank of gas and toolkit).

    I can pedal it, but I rarely do for any distance. The extra weight isn't bad when pedalling, but is noticable pushing it up the bridge with a rear flat. ;)
     

Share This Page