Motor mount; Clamp vs Welding

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by Big Bill, Jun 24, 2013.

  1. Big Bill

    Big Bill New Member

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    I am starting a new build so I need to decide weather to weld or clamp the
    motor mounts to the frame , My Schwinn lasted about 5K miles
    before the frame broke right above the weld the people who have seen
    the frame said it looks like it got to hot when it was welded.

    The new frame is a Dyno Glide using a jackshaft dive system that looks like
    AGKs set up ( I made all the machined parts and bought the gears and clutch from AGK ). The cylinder will be standing up .

    Thanks for the help Bill
     
  2. bigbutterbean

    bigbutterbean New Member

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    Welding makes for a much easier and more stable mounting, however the problem is that you need to make absolutely sure the motor mount is where you want it and positioned level before you weld it, or you're kinda screwed. I thought about welding my motor mount, but in the end opted to clamp. I fashioned a 3rd motor mount out of a kit tensioner bracket. I put it in a vise and hit it with a hammer to bend it to the angle I wanted, bolted one end to my frame and the other end to my jackshaft. I also had to cut shims for the motor mount clamps because I have a skinny frame. Cut the shims out of an already damaged bike frame. But if you can position the motor mount properly before welding, that seems to be the way to go.
     
  3. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    I prefer to make steel mounts to bolt the engines on whenever possible! ;)

    Every now & then a frame will crack right beside the new weld from the engines vibrations. :(
     
  4. biknut

    biknut Active Member

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    So far I've bolted all my motors in the frame, and I haven't had any problems.
     
  5. Mattjb

    Mattjb New Member

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    Majority of bike frames are thin (16g-18g) maybe less. Any undercut caused by welding not only makes a thin piece of metal thinner but also creates a point in the metal. I forgot technical term. Think of it this way, unfold a paper clip and in the center create a notch or indentation, now grab both sides of said paper clip and bend back and forth. It'll break where the notch was. Same thing will happen on your frame. Can it be welded? Sure. I'd go with a clamping method of some kind though unless ya have a heavy walled (thick tubing) frame. Just my 2cents
     
  6. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Welding can weaken an already built production frame. If you're building a frame from the ground up, by all means incorporate the engine mount as part of the frame......you'ld be mad if ya didn't.

    Clamping works just fine and can be as strong, if not stronger. Here's the way I did mine in a Dyno-Glide frame with the engine mounted up-right as you are going to do.......

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Just a little food for thought for ya.
     
  7. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Scott's engine mounts are as solid as you're ever gonna get! :eek:

    Jeff (CCC) also makes really hard core engine mounts for 4-strokes. (^)
     
  8. "the prussian" Shop Dogs

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    Good ole muffler clamps always work....
     
  9. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    I use small muffler clamps too.....I've got 4 of them on my race bike of various sizes. They are plenty strong.

    dnut
     
  10. "the prussian" Shop Dogs

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    Dont have a pic ,but they also make great tank mounts if u use two pairs back to back. Put a reg bolt thru and use a strip of metal to reach out to the tank bolts, rock solid!
     
  11. Big Bill

    Big Bill New Member

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    Thanks for the replies guys.

    Well it looks like I will be clamping the motor in the frame.
    I found Scott-o's and CCC's builds the other day and all I can say
    is WOW!! nice job. I will start a build tread this week end.

    Thanks again Bill
     
  12. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Here's another alternative that I came up with... I welded some 1/2 pipes to the ends of a kit 4-stroke mount to make a super solid engine mount for a 99cc Predator engine on a aluminum Felt frame.

    The engine is already rock solid before even securing it to the frame, & the design of the two 1/2 pipes helps protect the aluminum frame from damage from the engine vibrations! (^)
     

    Attached Files:

    #12 Venice Motor Bikes, Jun 25, 2013
    Last edited: Jun 25, 2013
  13. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    I like it Norm, very nice and the engine sits in the slanted position (^) Funny cuz I'm doing something similar for one of my sons bikes using the 79cc HF.

    .wee.
     
  14. "the prussian" Shop Dogs

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    Yea i like that ,all the offset one might need is all in the plate vs in the mount to the bike. Ive been trying to do something sim. To fit a grubee to a felt slater hummm...
     
  15. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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  16. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

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    Awesome idea for a mount.

    The 99 cc HF race class is going to be a very popular and fun.
     
  17. Big Bill

    Big Bill New Member

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    Venice Bikes Nice Job !!

    Now that has got to be one strong Mount
    It looks like you can use a few hose clamps and let it rip.
    I just picked up Lincoln 140 HD welder a few months, but my welding
    skills are still a little rough. Your mount is giving me some good
    idea's.

    Thanks Bill
     

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