finished 2-stroke mongoose beast

Discussion in 'Photos & Bicycle Builds' started by Rebel Riders MB, Feb 5, 2015.

  1. Rebel Riders MB

    Rebel Riders MB New Member

    after a while I finally finished my mongoose beast design. I had to cut and re-weld the frame to offset the engine and gain chain clearance around the tire. so this is it , my hand made custom frame beast with sprocket hub adapter,clutch cable roller, and offset intake manifold,

    FOR SALE (message ME)

    P1231003.jpg P1231004.jpg P2041050.jpg P2041046.jpg P2041048.jpg P2041049.jpg

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  2. butre

    butre Well-Known Member

    that mounting is sketchy as hell, most people motorize those things with a jackshaft
  3. cmb271

    cmb271 Member

    I'm not getting good vibes from that mount either, but to each their own, I would of just ran it from a mount behind the seat if clearence was an issue.
  4. Rebel Riders MB

    Rebel Riders MB New Member

    Wouldnt A jack shaft would be kinda pointless since its a single speed? I don't think the rewelds will be an issue. If my welds are solid which I believe they are then it should run just fine, what could go wrong. . . vibration breaking the weld? Well I guess its trial and error but its been doing just fine so far
  5. KCvale

    KCvale Motorized Bicycle Vendor

    As I mentioned to RR in his 'for sale' topic on the other MB site I sure hope he is selling it as a piece of art and not a functional reliable motorized bike.

    What can wrong?
    You have no frame integrity, that comes from good round tubes from point A to point B.


    Maybe with a thick metal plate to span the distance in between with each tube welded all the way around would hold up but the tubes just butted edge to edge sure won't.

    Sadly you are betting your own and now apparently someone else's life it will.

    Don't get me wrong here RR, it looks beautiful and clean, nice work with that, it is just structurally disastrous.
    Last edited: Feb 8, 2015
  6. Timbone

    Timbone Active Member

    This looks very strange.

    Bicycles are made the way they are for a reason. Tubing has great strength per their relative light weight. When you cut a tube, offset it, and weld together the remainder, you have a bicycle frame that is compromised.

    These Chinese two strokes create a great deal of vibration. That cannot be underestimated. When you start getting over 5000 RPMs, every part of your frame (and motor mounts) will be under intense strain.

    Interesting experiment, but don't expect this to end well.
  7. el diablo guapo

    el diablo guapo New Member

    first, i LOVE this implementation! it really gets at looking past what you are actually looking at, to do the thing you want to do. it is dramatic.

    could something go wrong? it is likely, yes. but as a kustomizer of stuff, that is part of the deal. and it amazing what does actually work.

    but you definitely need to keep an eye on the situation as you test it out. i have personally ridden unusual items for years, but my 12 year old neighbor can bust the same stuff in short order

    it seems that a less dramatic implementation might have been to make a paralel tube as a mount, but so much less cool. even a strap on the outside would add strength, but again, reduce the impact.

    how thick are the joiner plates/caps? a really thick plate could surely work

    i will be curious to see how this holds up over time, please follow up

    this has captured my imagination due to its counter-intuitivenes
  8. Rebel Riders MB

    Rebel Riders MB New Member

    Its sad to see every one so against this build, I WAS proud of it but I get it, its a flawed design .I know i still have a lot to learn So I guess I won't sell it , I will however ride it myself on dirt trails and the beach and see if it passes the test of time, it has about 8 hours of ride time so far and hasn't had any problems , (yet apparently). . .it gets alot of attention !

    Diablo: The plates I used on the ends are .7mm thick I cut out ovals/an 8 shape to move the bars

    KC: What other motorbike site? I'm only in this one I haven't posted this bike any where else, just once here.
  9. Timbone

    Timbone Active Member

    You are already riding it? Hey, that is the test! We don't want you to get hurt. I see this as an interesting experiment. How does feel at high RPM and maximum HT vibration? Is the engine absolutely rock solid in its mounts?
  10. KCvale

    KCvale Motorized Bicycle Vendor

    RR: Must have been a for sale post here.

    The real test will come if you ever jump or bind the chain at speed.
    I have seen that sheer a seat tube on one and literally rip the engine sideways out to the left with a poor front mount om another.

    Hopefully you will never see that.
    Also note I didn't see a plate between the tubes, I guess that's the 8 shape of it.
    That will sure help as it looked like you just end butt welded the tube edges and filled the center holes.

    If that piece were a pretty thick oval and really good welds it would have better chance of taking the punishment.
    Just keep a keen eye on it and do the standard motor mount test before riding:

    Hold the top bar with one hand.
    Hold the engine head with the other hand.
    Push back and forth AS HARD AS YOU CAN.
    If the engine moves AT ALL that is a fail.

    Good luck and stay safe bud.
  11. Rebel Riders MB

    Rebel Riders MB New Member

    Yes I do have thick 8shaped plates welded all the way around the reposition bars and the rest of the frame, they have been holding up great but for added peace of mind on the frame integrity I will be adding a 1in solid steel bar in the gaps I've created on The down tube and seat post then I will have full confidence to jump this beast . I've done wheelies, took it mudding and on some bmx rythem tracks at a higher speeds it held up and worked great. The engine is sold on the frame in terms of wiggle/tilt

    It has a vibration at high rpms but I think that's because the front engine mount has a tiny gap in between the frame and engine case. The bike seems to top out around 25 mph this engine did 37mph on its last bike, not sure why its going slower maby is the weight of the beast .
    I can clutch in and rev the engine into its top rpm but while riding wot the engine won't get into the same high rpm range maby I need a new expansion exhaust
  12. troyg

    troyg Member

    It's something to be proud of, and the only reason people are speaking, is not to be against you, but not "FOR" obvious danger.The fat tires will elongate the duration, but one of those is sure to start bending and or break.Look at every weld on (a good) bike, those are properly buttressed and still fail on occasion.Maybe some gussets, and prayer. PS: When it goes it looks like it will cave to the left, so I guess the motor may stop a complete fold.