BIG Problem with Front Mount and my Bike :)

Discussion in 'Motorized Bicycle General Discussion' started by longhorn6, Sep 3, 2009.

  1. xlite

    xlite New Member

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    Aha... a little island of sanity in a sea of JB silliness. Speaking of which might as well use Silly Putty in most cases.

    It's amazing what some think they can get away with. Wishful thinking at best, tragic surprise at worst.
     
  2. Saddletramp1200

    Saddletramp1200 Custom MB Buiilder

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    The guy's motor is dead. a 24 lb sledge hammer is the only respectful means to cure it. Dax has new motors for around 90.00. Some members here are so poor, (or cheap) that they will go to any means to get one more mile out of these little motors. Humor is part of this forum also. (c)
     
  3. moosinatrix

    moosinatrix New Member

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    If you Really wanna save a motor just run a bracke from the clutch cover bolt to the seat post, and for the front mount file the mount evenly as someone already said, retap the holes and as long as you still have half an inch or more threads left in there (might have to drill a tad bit deeper) use a shorter bolt just dont over tighten!

    And JB weld blows!! i have never had it work on anything, not even temporarily!

    Also i think alot of the motor mounts i have seen on these engine suck! the U shape in the mount is there for a reason, and taking a 2 bolt mount and reducing it to one is justt asking for trouble. i would get rid of the lower plate and make another plate that has a U Shape identical to the motors' and just get longer bolts and clamp the engine to the frame rather then damage your bike frame and engine with their method.
     
  4. Scotchmo

    Scotchmo New Member

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    Exactly! The front motor mount is designed to nest firmly around the down tube. Anything else puts extra stress on the mounting studs. If you do it the right way, the studs will not be ripping out the side of the motor mount. The half round recess in the engine block should be taking all of the side loads. If the motor is wedged down into a properly sized V of the down tube and seat tube, the mounting studs will have negligible horizontal shear stress. I would not use most of the large tube adapters that I have seen. Drilling a hole through the down tube at the point of highest stress will compound the problem. That creates a stress concentration that could eventually result in fatigue and failure of the frame. A steel plate cantilevered off of a single muffler clamp or u-bolt is also a poor solution. I’m not saying that these adaptations can’t work, but don’t be surprised when there is a failure.
     
  5. longhorn6

    longhorn6 New Member

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    big bike frame :( wont fit, its a cruiser, have to compromise.
     
  6. deacon

    deacon minor bike philosopher

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    Was my biggest fear when I had one of those motors...
     
  7. BarelyAWake

    BarelyAWake New Member

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    By far the biggest problem is there's only two points of contact for these shaky lil motors and both the mounts are quite low. I've tried to figure a third, but I've only succeeded in making my brain hurt...

    I swear on some of these builds it looks like I could grab the muffler and with a good sideways yank, pull it out of alignment at the very least.

    As I hit the trails a lot, this worries me :(
     
  8. 2door

    2door Moderator
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    Harley Davidson had a great idea some years ago. I found this picture somewhere, can't recall where it came from but what's interesting is the engine mount from the cylinder head to the frame.
    Personnaly I've never had a problem with broken mounts or fasteners but apparently I'm the exception due to the number of posts I see regarding this problem. Too bad the designers of our little 2 strokers didn't foresee the potential for engine mount failures and do something like the one below. A good machinist could probably copy this idea with a new cylinder head.
    Tom
     

    Attached Files:

    #28 2door, Sep 6, 2009
    Last edited: Sep 6, 2009
  9. BarelyAWake

    BarelyAWake New Member

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    Yeah - thats exactly what I was envisioning, but for the life of me I can't figure it out. I'm worried about the strength/proper torque of the head studs/nuts should I fashion a bracket to mount to them and I cant quite figure the connection to the bike's frame...

    yet...

    *bangs brain on wall*
     

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