U-Clamp large frame engine mount adapter. How to install?

Discussion in 'Frame Mounted Engines' started by dmfelicia, Feb 6, 2010.

  1. dmfelicia

    dmfelicia New Member

    I have a kit from Boy Go Fast and it includes a U-Clamp engine mount adapter for bikes with large lower frames

    Only thing it didn't include instructions for installation. I can probably come up with a way to mount it but I figure its better to ask someone who has done this, I wouldn't want my engine to come flying off :grin5:.


  2. GearNut

    GearNut Active Member

    Pictures are worth a thousand words. Look in the photo section. :)
  3. dmfelicia

    dmfelicia New Member

    Awesome idea! Thanks!

    Thanks for the idea. So simple but so helpful.

  4. Stan4d

    Stan4d New Member

    Look at my bike....I got the large U-clamp from BGF also. Used it and after test runs the motor kept slipping to the left in front. It is not a good way to mount. I used the U-clamp to hold the mount in place, removed the motor and drilled the frame and used a bolt to hold the front mount. Little more work, but motor stays in place. I would also recommend replacing the tensioner. Mine failed after less than 5 minuets. Got a more durable one from Spooky tooth. Good luck and remember that first build is the tinker build.
  5. dmfelicia

    dmfelicia New Member

    I see...

    Yup I know what you mean. I have looked at a couple of bike mount pictures and I have seen the engine mounted both ways, but i think the screw through the front tube is most prevalent it is definitely the best mechanical way to prevent the rotation you describe. With my set up I think the rear mount may prevent that type of slippage as the U mount fits nicely around the tube somewhat restricting that type of rotation. I have used some rubber shims and I am hoping these will hold otherwise I will have to employ the solution you describe; although I dont know if I have the proper drill and i definitely don't have the appropriate bits. I will post pics of my mounting.

    That's too bad about the tensioner hopefully mine will hold up better. Otherwise I will employ your solution as well. Thanks for all the help.

    One more question about the throttle grip. Did you have to punch a hole in the grip to mount it? If so how did you do this? What type of drill bit did you need to drill through that steel? Finally how do you get off those rubber grips, by cutting them?

    Sorry for all the questions.

  6. GearNut

    GearNut Active Member

    I do not recommend drilling any holes in your bicycle frame, anywhere.
    The stresses induced on a simple frame by these engines really makes them flex, and the last thing you want is a weakened frame tube.
  7. Whizzerd

    Whizzerd Member

    I've used the BGF U-clamp on three builds w/ no flexing issues BUT replaced the U-clamp itself w/ same size purchased from Fastenall. The threads will strip on the BGF unit if U ever have to loosen and retighten the mount. I also "double nut" the U-clamp. Also a convenient place to ground the magneto. I use the included rubber pieces on the tank installation. I wrap some duct tape(one thickness) where the mounts attach to prevent scratching the frame. Many on the forums recommend NOT to rubber mount the engine. The flexing can cause mounting studs to break. After installation, I remove the plug, ground it to the head and roll the bike to check for spark. DO NOT do this w/ plug ungrounded as that can blow the CDI. Checking for spark before your first start can help immensely. Hope this helps.
  8. dmfelicia

    dmfelicia New Member

    Thanks Whizzerd. This does help a lot. Makes total sense. By the way I figured out all my questions about the throttle grip I asked in post #5.

  9. Stan4d

    Stan4d New Member

    I do agree with gearnut to a point. I will inspect my mount frequently for any signs of stress failure. I have not heard of any tube failures due to drilling the mount hole. If you choose this method, just do not overdo it, to the point of weakening the tube.
    Thank you Gearnut for pointing out something that I havent thought about. :idea: