SON OF A....... (broken mounts snapped bolts)

Discussion in '2-Stroke Engines' started by lsoult, May 12, 2011.

  1. lsoult

    lsoult Member

    This morning started like any other. Jumped on the bike, started down my road. Wind in my hair, smile on my face. Revelling in the glory and satisfaction that I actually made my bike work. "Gas prices??? What gas prices????"

    Thats when it happened; A loud snapping follow by a violent shaking. I looked down, and much to my dismay; It appeared that my vertical mounting studs have snapped off inside the motor and my mount had a big crack in it (pics attached). Luckily, I didnt get far. So I picked up my motor mount (and my pride) off the ground and proceded to push the bike back to the house. Took a couple pics and jumped in the car.

    I was so pleased that my bike was operational. Now I'm just disheartend.

    Any tips on how to fix this? I'm thinking 'easy out' tool. But I have a feeling I'll end up making it worse.

    Attached Files:

  2. olow

    olow Member

    i would say easy out myself hope 4 the best
    WINDY CITY BOB likes this.
  3. lsoult

    lsoult Member

    Luckily one of my shop guys offered to help with that. He's removed a stud or two :)
  4. retromike3

    retromike3 Member

    your not alone

    I had a similar thing happen to me last year. I was able to get the first set out but they failed again. I drilled and tapped another set but they broke with the rear flange of the motor. I since then bought a different rear mount from Sick Bike Part (I have way to big of a seat tube) and also got a kit of stronger hardware from the same guys. I also had to get a new engine(sigh)

    No problem so far(knock on wood)

  5. lsoult

    lsoult Member

    New Engine???.... Stop trying to scare me... LOL.... I'd have to have it delivered to work and hide the old one from my wife (since I just got this one).

    I'm going to try to make this one work. Although I'm a little discouraged I'm bot giving up. :) yet
  6. GearNut

    GearNut Active Member

    Either easy out the studs, or rosette weld a nut to the face of them and turn them out with a wrench.
    As for the mounting spacer cracking like that, how well does it fit to the seat post tube?
    They tend to be too small for the frame tube. If the inside curve of it does not match up to the outside curve of the frame tube it will put a spreading strain against the mount and crack it. It is fairly easy to match up the inside curve of the mount by using sand paper and a piece of pipe. I used 3/4 inch sprinkler pipe and tightly wrapped it with newspaper to get the desired diameter before wrapping it with 150 grit sand paper. (take into account the thickness of the sand paper too) Use it like a file and check the fit often.
  7. Al.Fisherman

    Al.Fisherman Active Member

  8. retromike3

    retromike3 Member

    filing might be a problem

    The problem i had with my first engine was that my seat tube was way to thick and what I did was to file my old mount till it fit. That lasted for about an hour until it broke so I made my own rear mount. The mount seemed to work well but I changed the position of the motor so I could get less slack in the chain(big mistake) with the engine moved forward an extra inch and a half it put too much strain on the block of the motor and it cracked.

    I solved that problem by getting rid of the vertical drop outs and swapping them over with horizontal track type ends.I had to add a rear derailleur hanger on the pedal side so I could keep my eight speed freehub. Now if I want to tighten the chain I just move the wheel back a bit and the problem is solved. I did have to be very careful with the placement of the rear dropouts though because now I had to worry about were the brakes shoes hit on the rear rim.


    So far so good, and I have about ten hours on this particular set up.(according to my tack)

    Last edited: May 12, 2011
  9. lsoult

    lsoult Member

    I like the idea of making my own mount. Luckily I have an entire fab industrial fab shop to my disposal. What are "drop outs" anyway?
  10. CAMadam

    CAMadam New Member

    I had a very similar situation happen but I had the studs sheer off inside the block. After this and my attempt to fix it I would not recommend an ez out, bad idea and did not work very well at all. I took the engine off of my bike and brought it to a local welder and he welded the mounting spacer directly to the block and taped it. I now have a rock solid mount and larger studs holing it on. This has been done now for several months with about 150 to 175 miles on it and looking good. Also it only cost me 20 bucks to have it done and no more headache
  11. GearNut

    GearNut Active Member

    Drop outs are the metal brackets on the rear of frame that have slots in them where the rear wheel's axle slides into.
  12. Lazieboy

    Lazieboy Member


    Been there done that. Local lawn mower shop backed them out for cheap. I got stronger bolts from fastenal.
  13. olow

    olow Member

    did u ever here of hemostats
  14. lsoult

    lsoult Member

    Since my studs are recessed a little im not sure if hemos will get a grip but its worth a shot. I called the local mower shop. They're picky about what they work on but I heard there's a saw shop up the road that'll work on anything that pays...... we have a fastenal too. :)

    I had no idea that my bike would be an involved hobby. That's ok if I can keep the breakdowns down to twice a year.......

    Thanks for the tips guys!!
  15. GearNut

    GearNut Active Member

    If the studs are broken off below the surface too far to zap a nut onto the end of them, you can always stick weld to the end face of them and shut down the welder in mid weld. If done correctly you end up having a welding rod welded to the end of the sub-surface stud. Plenty to grip with pliers or vice grips and unscrew the whole mess.
  16. olow

    olow Member

    there is one thing u can do its a kit u buy and it has the drill bit some kind of a tool to put these things in the hole and new temper bolts diff. sizes what happens is as ur putting the studs in they expand the collar had this done to my outboard prop shaft and was better than brand new just cant remember the name of the kit thought the name was hemmo stat kit trust me once u install these u can take it back off and retighten again and again
    Last edited: May 14, 2011
  17. DuctTapedGoat

    DuctTapedGoat Active Member

    You can drill it out and tap it larger, or you can use a helicoil kit.

    But regardless - whenever you go to replace things - get grade 5+ bolts.
  18. rustycase

    rustycase New Member

    Thanks to the group for this thread!
    ...Just convinced me to tear my basketcase down further and replace the MM bolts with grade 8's before I go any further on the project.
    I just bought 9 grade 8 M6's for the rag joint, today.
    Some of the old ones were ate partly through by the spokes. I've already replaced the broken spokes. Where is the best place to get 12g spokes???

  19. lsoult

    lsoult Member

    I didnt even know you can replace spokes. Thats two things I learned from this forum in the last 10 min.
  20. Oddzball

    Oddzball Member

    Best thing to do bud from what i see is to get the actual adapter and put the sprocket directly on the hub. Honestly I am suprised most people dont do that.

    I wouldnt waste money on spokes, I am pretty sure that hub adpater is less than 50 bucks.