Motor mount dimensions

Discussion in 'Frame Mounted Engines' started by jmccrury, Jul 22, 2008.

  1. jmccrury

    jmccrury Member

    I got my 49cc HT kit in yesterday and have started building it. I am going to have to drill through the frame and make a bracket to mount the motor to. I thought that the bike frame was going to be small enough, but it's not. Too bad.

    Anyways, I was just going to make a simple bracket with three holes in it (like I've see other people do here) at work today, but I was in a rush this morning and didn't have time to get the dimensions. Does anyone know the distance between the motor mount studs and the size of the studs for drilling the bracket? I did a search but couldn't find this information anywhere. If not, I can get the measurements tonight and make it tomorrow, but I would really like to complete it today.

    Thanks
     

  2. likearock111

    likearock111 Guest

    I believe that the studs on the front mount of my Dax 70cc HT are 4cm apart. I don't know what diameter they are. Can someone back me up on this?

    -Rock
     
  3. jmccrury

    jmccrury Member

    thanks for the input. that looks about right when i measure it out.
     
  4. crazeehorse

    crazeehorse Member

    the studs are 1-5/8 inches center to center, the stud size is 6 mm , but a 1/4 inch bit will do.
     
  5. likearock111

    likearock111 Guest

    I could be wrong, but seeing how everything else on the motor seems to be in metric, I doubt the studs are actually separated by 1-5/8 inches. Also, 1-5/8" = 4.1275 cm. Prolly won't matter, though, if you drill the holes a bit big. We're working with HT tolerances here, after all!
     
  6. jmccrury

    jmccrury Member

    Thanks for the help. 1-5/8" and 4cm are close enough. I had already planned on using a 1/4" bit to drill the holes so it should work out ok. Maybe I will finally get it mounted today.
     
  7. crazeehorse

    crazeehorse Member

    sorry guys, i did'nt have a metric ruler, or tape, shame on me, anyways, i just measured mine so i know it will work. i ran a sheet metal bussiness for a long time, i'm old school, i can measure metric if it's critical, but i default to the inch system..
    mine did break a 3/8 bolt that i put through the frame, but it was poor grade material. i used a 3/8 head bolt from a briggs & straton motor, nice & hard. also if you can find some small rubber gromets to put on the engine mount studs, between the peice your making & the nuts & washers, that takes a lot of vibration out, you can always get them at the auto parts store, & add them later.
     
  8. jmccrury

    jmccrury Member

    That's ok, I was going to have to convert the metric to standard anyways. The tooling guys here always want everything converted even though we work in automotive and everything is metric.:rolleyes: They are old school too.:grin:

    I also have a solid rubber tube that I'm going to make my own grommets from. It was too soft for the application we wanted it for here at work, so I got it for free. It should work great for mounting the motor.
     
  9. crazeehorse

    crazeehorse Member

    sounds like you are going to have a very good install, i used peices of an 1-1/4 inch rubber dishwasher hose to put between the engine, & the seat post tube, all that rubber makes a big difference. i tried without it, it gave me the (numb bunn syndrome) not a good thing for a long ride.
     
  10. GasKicker

    GasKicker Member

    As a suggestion, I used one of the mounting brackets which came with the engine as a template for drilling the holes, (no measuring neccessary), and I made "grommets" from sections of leftover fuel line. Works well for me.
     
  11. crazeehorse

    crazeehorse Member

    only problem there, if i had to take it somewhere, i would forget the mount, but i agree, nothing beats a template.
     
  12. ihatemybike

    ihatemybike Member

    Don't drill your frame! Yes I know the instructions say to, but doing so adds a weak point to the frame. Find another creative way to clamp the down tube....u-bolts, threaded rods, anything that doesn't change the integrity of the frame.
     
  13. crazeehorse

    crazeehorse Member

    i have done two so far, with no problems. mine are steel frame bikes, so i don't wory about the integrity, i have been running my first build for almost 4 months on some rough roads with no signs of trouble.i do inspect often though. besides i have a mig welder, so at least on my bike, if i lose the frame integrity, i can rapidly restore it. i don't think i would want to drill an alloy frame .
     
  14. ihatemybike

    ihatemybike Member

    You have a mig, why not weld a mount to the frame?
     
  15. crazeehorse

    crazeehorse Member

    that's an thought, maybe on my next one, or for the repair, if my frame does crack. i guess i did it cause it was quick, & i'm lazy, i wanted to ride. if i did'nt have the shop that i do, i would have to be much more cautious.
     
  16. softride

    softride Member

    engine mount

    does anyone have pix of alternate mounts for front of a generic chengine (blue collar 70 )
    my cruiser has thicker down tube so front mount will not slide around tube I was thinking i could make a plate to bolt on the engine and then a plate to sandwich the frame tube this is on a sun Atlas cruiser http://www.janddbicycles.com/bikes/sun_industrial_atlas-bike.jpg
    Thanks
     
    Last edited: Jul 26, 2008
  17. crazeehorse

    crazeehorse Member

  18. softride

    softride Member

    thanks

    Thanks
    thats exactly what i was thinking of
     
  19. TWalker

    TWalker Guest

    Dont drill if you can help it. If you cant make a bracket even denting the frame in is better than drilling. Even if you have to take a hammer and tap in the frame where the studs are the frame maintains its integrity better in my opinion.

    Ive built many drilled and non-drilled and Ive found making the frame fit the engine mount is a better alternative. Wrap some tape or something around the frame and no one will notice.
     
Loading...