Broken Motor Mount

Discussion in 'Motorized Bicycle General Discussion' started by SmokerX, Apr 30, 2009.

  1. SmokerX

    SmokerX New Member

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    I traded my tensioner wheel out for a skateboard wheel i modded so I could have bearings
    also my old tensioner wheel pin was de-threaded so i switched it out for an american bolt and
    nut. Well the lock-tite and crimping of the threads came loose and the nut started backing off and eventually the wheel tilted enough to rub the tensioner bracket. This catching action I believe
    started pulling the chain and then engine since its attached. Eventually enough tugging occurred
    to rip one of the bottom brackets bolts thru the bracket and break the other bolt flush with
    the engine. I cant get the broken bolt out to replace the bracket and broken bolt, So I flipped it around so the good bolt and good bracket hole are together, so I have one bottom bracket bolt holding
    the engine. My frame is fat so the bottom bracket is a bolt thru the frame then a stack of
    washers as a spacer then a back bracket for a frame mount flipped upside down and a third hole
    drilled for the frame bolt (not my build). It could also been caused by friction but when the bottom bracket failed, while pushing, every time the tensioner wheel would catch the motor pulled out of
    the frame.

    I dunno im going to ride it with 1 bottom bracket bolt and see how long it lasts. but im switching
    out the skate wheel for a new tensioner wheel since it comes w the pin and I`ll put proper speed bearings in if need be to get what advantages come with a skate wheel. All in All very depressing
    to lose an entire operating engine to a 2 inch piece of chinese all-thread. THinking back i wished i would have switched those bolts out for something that bends instead of breaks,,,,like AMERICAN STEEL wtf these chinese bolts are like pot metal.:-||:-||
     
    #1 SmokerX, Apr 30, 2009
    Last edited by a moderator: Apr 30, 2009
  2. Finfan

    Finfan New Member

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    You'll need to get an "easy out" if the stud is broken off flush. I have replaced the factory studs with pieces of "all thread" that you can get at most hardware stores. Just cut them to size and turn them in. I have been having problems with the studs stripping out of the block/cylinder on mine. Be careful with how much torque you use!

    :-||
     
  3. SmokerX

    SmokerX New Member

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    thanks for the info. I`ve been neglecting it and didnt get an easy-out and rode on the single bolt. The second bolt fell out so I now have to fix it to ride it again. I`ll have to extract the other broken bolt and get a proper mount.

    Anybody know the size of the bottom mount bolt? I`d have to extract the broken bolt to figure this out and you need the proper sized easy out.
     
  4. SmokerX

    SmokerX New Member

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    The proper size is 6m metric. I got a bolt and cut the head off for the bolt that fell out. I tried to extract the other bolt with a bolt extracting kit i got for 10 bucks at harbor freight but no luck. The counter sinking extractor sank, but when i tried to turn it the bolt wouldnt budge. So i guess i have to drill this out and rethread it. I put the old gas i took out back in, but it sounds like the gas is bad so the bike will fire poorly but not go or idle. I gotta go get new gas to test whether its rideable again.
     
  5. Finfan

    Finfan New Member

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    I think the next size up is 1/4 inch if you're real careful while drilling. Otherwise you can go to 8mm. Just be careful of your frame clearance. Good luck!
     
  6. impression

    impression New Member

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    i would drill it out, get it aluminum welded shut/filled and then get it re-tapped to 6mm
    cost is about $50 from an engineering shop
     
  7. lordoflightaz

    lordoflightaz New Member

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    At $50, that sounds like get a new motor for a couple bucks more.
     
  8. impression

    impression New Member

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    well wheren i live it's $180 for a new engine and the one i'm getting done right now i know it revs really well so i think it's worth it.
     
  9. SmokerX

    SmokerX New Member

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    I`m still riding on the single bolt. It fell out and I have a post about fixing the ignition system from the engine popping out of the frame. It`s probably stressing the other mount since none of the shaking is being transferred into the frame(no nut on the single bolt, just a bolt keeping the engine from popping out) But that also means less shaking is being transferred into me. I`ll keep it with the one bolt since i`m lazy and its still rideable :p
     
  10. Cabinfever1977

    Cabinfever1977 New Member

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    try putting a metal strap from engine exaust bolt to top bike frame for extra support.
    and a muffler strap will help.
     
  11. justthisguy1292

    justthisguy1292 New Member

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    i kinda have a similar problem with bolts breaking. the left bottom bracket bolt broke and i replaced it with "american steel" but that broke too. oil or some black sludgy stuff would slowly leak out of the hole too. I figured i could avoid the whole situation if i put a sbp shift kit on, so i did. It worked great for a while, but recently i noticed more vibrations and i checked and sure enough that same bolt had come completely undone and i think it might have snapped too but its hard to tell with shift kit still on. why does that bolt chronically snap even with the shift kit? I'm stumped!
     
  12. reg454

    reg454 New Member

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    1/4" 20 is the next good size to retap the threads the bolts will get a good grip and be tight. I retapped 90% of allthe threads on my engine. The only ones I havent yet are the rear mounts (i found good bolts for it) the head bolts and the magneto cover.
     
  13. freewheeling frank

    freewheeling frank New Member

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    might wanna check out sick bike parts mounting hardware they make good stuff and are really good to deal with, frank
     

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