Engine Block Problem (Mounting Studs Are Broken)

Discussion in 'Motorized Bicycle General Discussion' started by mxchris727, Aug 12, 2009.

  1. mxchris727

    mxchris727 New Member

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    Hole In The Engine Block

    I was taking a long ride yesterday, after I got back, I had realized the one of the mounting studs had broken off. Foolishly, I tried to drill it out but wound up making a hole in the engine itself! I tried to ignore it by using just one of the studs but almost instantly, that one broke off too. Now I am stuck with two broken studs in the engine and one hole that I drilled! Anyone know how to fix this?


    Picture: The hole on the left has a broken stud in it and the right has the same but a hole drilled next to it.
     

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    #1 mxchris727, Aug 12, 2009
    Last edited: Aug 12, 2009
  2. mxchris727

    mxchris727 New Member

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    Hole In The Engine Block

    -UPDATE-

    After drilling out both holes, I realized that I drilled too far into the engine and now there is no compression. Whenever the engine turns, the air comes out the hole I drilled instead of the exhaust.

    Is the engine dead now or can it be saved? I don't have a welder to use.
     
  3. caprirs302

    caprirs302 New Member

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    Re: Hole In The Engine Block

    More than likely its time to buy a new one and use that one for spare parts. The good news is that you can just buy the motor instead of a whole new kit and save a few bucks. Just for s*&ts and giggles you could go to the local hardware store, pick up a couple of studs or some goos all-thread and the BEST high heat epoxy that they have and try to hold the studs in that way. It should also seal your hole, if you don't put on so much that it drips into the engine. Its worth a shot.
     
  4. Junster

    Junster New Member

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    Try using a center punch and punch the seam in the second bolt at the same spot you drilled the other one. Put some masking tape around the drill so you know how deep your getting. Figure out what size grade 5 or 8 studs you can get at the local hardware and get the tap and nylock nuts to match. Get some JB weld. Tap the new holes. You may need to tap them till the tap bottoms out then either use a bottom tap or grind the end of the tap off till there's just a little taper on it to turn it into a bottom tap and thread the holes to the bottom. Install the new studs with the JB weld. Now get new metric studs for the intake, exhaust, front motor mount. Take the originals out put the new better studs in with Lok-tite blue. If you can't find studs use metric bolts. Don't wait for the same thing to happen all over your motor.
     
  5. vicsvw

    vicsvw New Member

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    The hole that’s been drilled off center is your biggest problem. I would pull the lower end apart and JB weld the hole from inside. When drilling out a stud start with a small bit and keep getting a little larger with each drill. The stud is slightly softer in the center so buy opening it up a little at a time the bits will gradually try to center in the stud. On the stud that hasn't been drilled, spend a lot of time center punching the stud, then drill it out to about .040 and set a std. 6mm nut(or ¼-20) on top of the stud. With a wire feed welder, spot-weld through the nut and onto the end of the stud. Weld the nut to the stud and after letting it cool a short time, try unscrewing the nut. If the nut brakes off weld on another nut until you get the stud out. I would drill out both holes (front mount, Ex studs and intake studs) with a #7 drill and tap with a 1/4-20 tap. Next get some good studs to replace the soft china ones. The one nice thing about the stud you drilled is that you can open it up to a 8mm if you have to. Next time take more time with the center punch. I drill all the 6mm out to ¼-20 as soon as I get a motor. The other nice thing is a replacement case is jut over $20.00. Have a Nice Day. Center Photo shows 6mm then 1/4-20 and bottom 8mm. Right showe 6mm , Broken Stud Drilled off center and lower is 1/4-20 American stud. Vic
     

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  6. mxchris727

    mxchris727 New Member

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    That's what I did, I started with a small size bit then continued to go bigger. Eventually I was at a perfect size and was able to screw the studs in tightly. BUT.... After I did this, I realized that I had drilled too far and now there is a hole in the cylinder! I don't think I could epoxy it because there is too much pressure in the block.

    I will try to upload pictures soon...
     
  7. vicsvw

    vicsvw New Member

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    Counter sink the hole from inside, Install stud and then fill countersunk hole from inside. This way the JB weld will hold 10 times the inside pressure. Vic
     
  8. vicsvw

    vicsvw New Member

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    The hole that’s been drilled off center is your biggest problem. I would pull the lower end apart and JB weld the hole from inside. When drilling out a stud start with a small bit and keep getting a little larger with each drill. The stud is slightly softer in the center so buy opening it up a little at a time the bits will gradually try to center in the stud. On the stud that hasn't been drilled, spend a lot of time center punching the stud, then drill it out to about .040 and set a std. 6mm nut(or ¼-20) on top of the stud. With a wire feed welder, spot-weld through the nut and onto the end of the stud. Weld the nut to the stud and after letting it cool a short time, try unscrewing the nut. If the nut brakes off weld on another nut until you get the stud out. I would drill out both holes (front mount, Ex studs and intake studs) with a #7 drill and tap with a 1/4-20 tap. Next get some good studs to replace the soft china ones. The one nice thing about the stud you drilled is that you can open it up to a 8mm if you have to. Next time take more time with the center punch. I drill all the 6mm out to ¼-20 as soon as I get a motor. The other nice thing is a replacement case is just over $20.00. Have a Nice Day. Center Photo shows 6mm then 1/4-20 and bottom 8mm. Right Photo 6mm top, Broken Stud Drilled off center and lower is 1/4-20 American stud. Vic
     
  9. HT2005

    HT2005 Member

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    You could buy a new lower engine block from one of the site sponsors; that is, if all else fails.
     
  10. mxchris727

    mxchris727 New Member

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    I don't own a welder and I don't think anyone I know dose. Even if I do weld it wont that affect the compression?
    Anyways, I tried epoxying it but the glue just popped out after I popped the clutch.

    Here are a few pictures of the block... I was able to screw the two studs in tightly but there is still that hole.
     

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  11. gberry50

    gberry50 New Member

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    I had the very same problem If you can work the stud out you can redrill the same holes
    with an "f" drill then tap for a 5/16-18 thread I used 4" cap screws and added an 1-3/4 alum.spacer but I needed room for the reed valve mod I was doing anyway. so far so good. dont drill any place else or you will have to repair case with jb as mentioned or replace cases or engine..duh.
     

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