Mounting studs broken!

Discussion in 'Motorized Bicycle Trouble Shooting' started by Newbiebike, Dec 29, 2011.

  1. Newbiebike

    Newbiebike New Member

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    I have had my bike for about 6 months. A couple months ago I heard a loud bang/crack while riding, while examining my bike I noticed one of the nuts on the back mounting stud was lose, I tightened it. I then noticed the other side was lose, however when I tightened it the whole stud slipped out because it broke off of the engine body! However because I'm an impatient teenager with much resistance against spending money just tightened the front mounts and hoped for the best. For Christmas I got an expansion chamber, I finally got it running today and it was running great but later I noticed it was making a rattle noise and vibrated allot. When I checked it I saw one of the FRONT mounting studs was gone. What should I do now? I know there are some welding places around here but I don't want to pay an hourly rate of like 60 bucks to get two bolts welded onto my bike. And plus I lost one of the bolts on the road somewhere. Someone please help with any ideas? I will appreciate any advice very much, I'm sure you all know how frustrating it is to put so much time and money into your bike and have it continuously breaking :/. Thanks!
     
  2. CTripps

    CTripps Active Member

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    Welcome to the forum.
    It can be frustrating sometimes, but the open road makes it all worth while. Best thing I can tell you to do is put "replacing mount studs" in the Google Search bar up top of the page. It spat out a pile of links at me.
    You might have to spend a bit of cash, but having the right tools for the job makes life a lot easier. You might also be able to get help if your school (or one nearby) has an auto shop or metal shop class room (wood shop doesn't help a lot for this ;)). You'd be surprised as well by how many smaller garage/engine repair type places will do you a favour if you help them out in some way. When I needed an exhaust pipe bent I stopped by a guy's place a block away. Ten minutes later I'm driving a van back for him from the brake shop a block away, twenty minutes later I'm waiting for the now bent pipe to cool enough to throw in the trunk of the car. Chatty guy too, though I never did get his name. Stopped by a couple days later to show him what the pipe was for, and he liked it.
     
  3. Super

    Super New Member

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    I'll tell you what I did. I went to the auto parts store and bought harden steel bolts to replace the studs. Mainly because the studs were striping while tightening.
     
  4. Newbiebike

    Newbiebike New Member

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    Thanks! I didn't realize the studs were replaceable. I tried to take out the broken studs with a GraBit tool which one of the people on the forums tried. but the broken stud wouldn't budge. I tried to remove one of the un-broken studs just to see if that would work and it just dug a deeper hole into the bolt. When I search "Replacing mount studs" most of the topics are about how to obtain the right sises and which type of metal to use. The are many steps that are left out because its probably just really simple or im missing out on something. What do you sugest for me to do to get the original studs out? Should just drill it out and buy tap drill? i dont know. Im completely clueless with this. Im sure i could figure it out but i just want to do it completely right.
     
  5. Bicycle Motor Fun

    Bicycle Motor Fun New Member

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    Newbiebike; you might try drilling them out with a left-hand drill bit(s). These studs are probably not a hard steel and using the left-hand drill bit, might just create some heat in drilling and with the proper removal rotation for the stud, remove it. The trick here, will be to get the drill centered as closely as possible in the center of the broken off stud so as not to drill into the engine casting. I have used this method before on some of my restoration projects and it has worked for me in some cases. Keep us posted on this form and good luck. BMF
     
  6. Al.Fisherman

    Al.Fisherman New Member

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    There are a couple of things that can be done. 1) is the actual case broken 2) Did you strip out the mounting holes 3) are the studs broken off in the threaded hole it self. I've used LEFT hand drill bits in the past and have good results. If the threads are striped, I'd drill the hole out for a 7mm STUD or a 5/16" STUD and rethread the hole. Your problem is one of the reasons why I preach about changing the studs to a Grade 8.8. Mounting a engine improperly will cause the same results.

    Engine mounting
    Engine Mounting pictures by Ron-Becker - Photobucket

    Broken case repair
    Broken mount repair pictures by Ron-Becker - Photobucket

    And this might be helpful
    https://docs.google.com/document/d/1GcesQihc7-mm3hJGf7UPiqOaRXZ8ekUT99QUZq2qXXE/edit

    One of the reasons why these engines don't hold up are those that are too impatient, and just throw a engine on a bike frame. With a little mods and proper care you can get many miles out of one. 5 out of my 6 builds are going strong..the 1 that isn't was because of a defective head gasket. Started building since 3/2009.
     
  7. MotorNut123

    MotorNut123 New Member

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    you can get a new engine hardware kit on sick bike parts. my exhaust stud stripped out today, so im going with the SBP kit.

    Sick Bike Parts
     
  8. donegood

    donegood New Member

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    JB Weld might work if there is enough room in the hole for the bolt otherwise tap and die it maybe.
     
  9. Al.Fisherman

    Al.Fisherman New Member

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    JB Weld has no place there.
     
  10. Hiigel

    Hiigel New Member

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    Go to about any hardware store and buy 5/16.wee.-18 Heli-Coilo kit to do the best job. You re-size the mounting bolt holes and thread a spring like device in with the special tool that comes with the kit, and then thread your new bolts in with Lock Tight or similar product. You will be amazed at the difference. With the Chinese motor, you have to be so careful of stripping bolt holes. This fix makes you able to tighten your head/body to the crank case with confidence you will not strip anything. Might be handy to have a torque wrench too.

    Gary
     
  11. maniac57

    maniac57 Old, Fat, and still faster than you

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    JB weld is useless on mounting applications. Vibration will break the epoxy every time.
     

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