Rear mounted engine on mountain bike

Discussion in 'Photos & Bicycle Builds' started by ace1, Sep 16, 2010.

  1. ace1

    ace1 New Member

    Here are some pictures of a rear mounted Chinese engine on a Walmart Mongoose double suspension bike. I used aluminum angle and the only tough part was the muffler extension. The cables needed to be replaced with longer ones. The ride is very smooth as you can imagine and after numerous tweaks to get it right, I am very pleased. I originally tried using rubber vibration isolators - Big mistake, it caused the chain to jamb and a sudden stop! Experience is a great teacher.

    Attached Files:

  2. srdavo

    srdavo Active Member

    Interesting concept.

    any problems with your carb being tilted ?
  3. ace1

    ace1 New Member

    I tried a carb extension but I couldn't make the motor idle properly and it was hard starting. So I tilted it and it works just as it did before on my non-suspension bike.

  4. hurricane

    hurricane Member

    what a differant and unique motor mount for that kind of engine and bike style. You did a wonderful job on the muffler extension. I must admit though it does look rather on the odd side ,but i could get used to it .

    good job on this build and making it work.
  5. ace1

    ace1 New Member

    Thanks for the Kudos. One thing more needs to be done and that is to make a bit of a heat shield over the muffler extension. Right now its a pretty good bum warmer on a long haul.
  6. 4950cycle

    4950cycle Member

    Not bad, not bad at all. I like it. All rear rack mounts look a bit on the odd side in my opinion, so don't feel bad. But I still preffer all the **** out behind me brother in I am building a HF Greyhound rear rack Mongoose full suspension MB. I like seeing how guys are getting these China girls on rear racks though.
  7. ace1

    ace1 New Member

    Please pass along some photos when you get 'er done.

  8. 4950cycle

    4950cycle Member

    I will be giveing this thread a blow by blow as I go. Should be no shortage of info as far as how everything is going along. And it should move along. As far as I know I am done stalling to look and order and such for parts and conponents I should need. Even know my final ratio already. BTW I am going jack shaft with belt drive on this build.
  9. 4950cycle

    4950cycle Member

    Whooops, That last reply is in the wrong thread. Sorry ace1:dunce::whistling:
  10. robin bird

    robin bird Member

    Very interesting mount !
  11. buzbikebklyn1

    buzbikebklyn1 New Member

    Rube Goldberg Is Alive And Well!

    I have to say, IO like the idea of a rack mounted china girl engine for a dual susp. bike...very innovative.
    Not to rag on your build... but you MIGHT just want to re think the motor mounts... again... very interesting build.
  12. 4950cycle

    4950cycle Member

    Are you sure you have the right fella ? I have a thread about an HF Greyhound rear rack build. But then again, You may have the right guy. My build doe's have the Willy Wonka/Rube Goldberg thing going on.LOL (I don't have a 2 stroke China build)
  13. buzbikebklyn1

    buzbikebklyn1 New Member

    OOps! my bad , that was meant for Ace1
    sorry dude.
  14. 4950cycle

    4950cycle Member

    That is funny though. Because as I had said, My rear rack build doe's an is going to resemble a Rube Goldberg contraption.
  15. buzbikebklyn1

    buzbikebklyn1 New Member

    Dude... my very first ride was a 1971 all steel Schwinn 10 speed frame in yellow, skinny 27" wheels side pull brakes and a pinned 52/38 tooth steel armed crank.
    (remember those tapered pins?)
    Into this I bolted a McCullough 54cc 2 stroke chainsaw engine, my dad had a crank adapter for a standard spin on type rear free wheel spun up and we ground off
    all but one of the clusters gears and bolted it to the crank and then the chain rings to the adapter.
    (just like a Sick bike parts freewheeling hub today)
    IT WAS A DEATH TRAP!... no brakes and such a narrow power band that it could wheelie by throttle and the wheels lasted a month!
    Motor mounts made from old steel shelving angle iron and strap, ground out with a bench grind stone and an angle grinder... it weighed a ton.
    BUT when it wasn't trying to kill me? IT WAS THE MOST FUN THING I EVER DID!
    Here i am...40 some years later... my building skills have improved as well as bicycle technology... but i still get that same feeling today test riding new builds.
    Last edited: Mar 28, 2011
  16. 4950cycle

    4950cycle Member

    I am 48 and my first build was only about 12 years ago when I lost my car and job for a while. But still needed to get around. So I took this Autobike that I had and put a briggs flathead 3 1/2 hp on it with a jackshaft and an 8 inch idustrial cart friction wheel. It like yours was insane heavy. But It was fast and fun for a motorized bicycle. I didn't know to watch out for weight on an MB build. I know now by golly ! On this build even though its a four stroke I am watching every calorie now without sacrificing comfort though. I still have that old build I slapped back together for a pic because Lowracer wanted to see it. I like to try new drivetrain ideas. This time its an HF Greyhound 2 1/2 hp with a two or three speed belt drive depending on how things go. On a 26" full suspension alum. Mongoose.
  17. buzbikebklyn1

    buzbikebklyn1 New Member

    Im thinking on a aluminum plate mini rack mount, 50cc 4 stroke Honda engine on a Giant or Univega dual suspension bike.
    Ive looked at all the rack systems and I think theres no need for all that extra weight if its been built strong enough, they can be pared down.

    I intend to use the rear sub frames(swing arm) V brake posts as the front of the rack mount and clevis rod ends with stainless steel internally threaded tubes as the rear supports.
    Its not going to be a friction drive, but a rear mounted jack shaft type, with a free wheeling crank via Sick Bike parts and my own custom made 415 chain, 5 speed on a 10 speed cassette body hub, with 5 custom made Kings rear gears and with one of my custom made aluminum pipe gas tanks balancing out the opposite side of the rack.
    look for it some time this July.

    It seems I've fought that one all my life, being in the high end of the bicycle business its our mantra...

    Cut ounces and the pounds will take care of themselves...

    At our shop we call these guys "weight weenies" willing to spend $100s of dollars to loose one pound of weight...
    I ADD 25 pounds to my bikes and they all do 45 plus MPH! If they didn't Id tear it apart and find out why.
    "Ill keep building and riding till i die"
    Indian Larry
  18. 4950cycle

    4950cycle Member

    I will end up needing a 10 to 12 inch tube like tank clear up on my handle bars. Its the only place high enough to feed my nonfuelpump carb. One thing at a time. Sounds like a very nice plan on your next build. My next will have an HS 4 stroke 50cc. They are supposed to be faster than the 70cc Greyhound. Not sure if its true. Cantact me anytime. John
  19. 4950cycle

    4950cycle Member

    BTW, My new build is not friction drive either. It is whizzer sheave (pulley /belt) drive. My old build was Mega friction drive. Jackshaft with sprockets/chains and 8 inch friction wheel.
  20. Lazieboy

    Lazieboy Member

    Did you do the almunim brackets. If so do you have a welder. Wish i did. O ya nice.