Engine Trouble someone please help front engine mount bolt broken inside

Discussion in '2-Stroke Engines' started by dotcom, Dec 9, 2014.

  1. dotcom

    dotcom Member

    One of my bolts broke off on the front engine mount most likely due to a series of events. I was wondering if anyone has tried the harbor freight extractor for this and if it worked. I think the rubber from inner tube that I tried to put around the mounts to prevent some of the normal vibration shrunk over time and caused some loosening of nuts around the mount which vibrated a complete bolt out of the rear mount. I knew I was starting to feel lots of extra vibration lately and I thought it was the engine,lol and today I found out why. Now I need to figure out how to get the darn broken bolt outta there. I've heard this is somewhat common so bring only the best replies :):)
    UPDATE: I purchased the extracting kit from harbor freight but I keep snapping the drill bits so I need to get some more tomorrow.
     
    Last edited: Dec 10, 2014

  2. dougsr.874

    dougsr.874 Active Member

    Most auto parts stores sell screw extractor kits.....most of the Chinese 2 strokes use 6mm mounting studs...so buy the right size....the kit also comes with a bit to drill a hole in the stud or bolt....if you mess the threads up you will need a tap also to rethread the hole.
     
  3. dotcom

    dotcom Member

    good to know
     
  4. crassius

    crassius Well-Known Member

    if all else fails, one can drill a couple holes straight down thru front of motor & bolt a couple pieces of angle iron to it for u-bolts top & bottom
     
  5. dotcom

    dotcom Member

    Please show an example. This sounds intriguing because I tried with an extractor kit that I bought today but I can't seem to drill deep enough without snapping the bits. I have to get more before I can try to finish. im thinking skeptically since i've never technically extracted such a thing so this sounds like a potentially descent back up plan.
     
    Last edited: Dec 10, 2014
  6. dotcom

    dotcom Member

    accidental duplicate post
     
    Last edited: Dec 10, 2014
  7. Bzura

    Bzura Member

    You can get a "grabbit" (I think that's how it's spelled) at one of the big box home improvement stores. It's got the appropriate size drill bit on one side and the extractor "grabber" on the other. Pretty much unbreakable.

    Or you could get a helicoil set and drill in out completely if the stud won't come out. The Helicoil insert will be stronger than threads into the aluminum block.
     
  8. crassius

    crassius Well-Known Member

    I don't have a pic handy of the angle iron fix & prefer helicoil if it can be done. If you get stuck, take a piece of angle iron & hold a flat side on top of the front mount so the other flat side is against the frame of the bike - this should suggest to you where to drill & mount the iron - I like to put 2 pieces on top & bottom & sometimes saw off a bit of the old 'ears' of original mount
     
  9. dotcom

    dotcom Member

    Ive never heard of helicoil or iron fix and would need to see an example, if possible, thanks
     
  10. crassius

    crassius Well-Known Member

    google 'angle iron' to see what it is - you'd only need 2 pieces about 2 inches long & about 1 inch high
     
    dotcom likes this.
  11. dotcom

    dotcom Member

    Ill look into it. Thanks
     
  12. mrbg

    mrbg Member

    busted motor mount studs?

    I've had a couple break on me, if they don't have loktite on em take a little hacksaw the cheapo 1handed jobber and cut a slot in the busted stud don't worry about cutting into the cases and try to keep it centered on the busted stud. Then put some liquid wrench or penetrating oil let it soak for a while and put yer lil flathead screwdriver in the slot and bear down on it and it should start backin out. Remember the width of scrwdrvr tip can't be bigger than the bolt diameter.and if you slip out of the slot just clean it up wit yer hacksw. I know it sounds okie but it works I've taken them out of friends bike, 1time with the motor still in bike with the chain on. I haven't had any luck with extractors on sml dia bolts. If you can't get it, drill and tap above it, and make the adjustment on mounting plate, if it's the rear you'll have to drill and tap 2 new holes so your bracket will work. If your not mechanically inclined find someone who is that's not gonna charge you more than the cost of a short motor!
     
  13. dotcom

    dotcom Member

    too late. Ive drilled too much for that method. Got new bits today. Gonna start it soon to se if I can finish the extracting process
     
  14. mrbg

    mrbg Member

    Oh well hope your able to salvage it
     
  15. KCvale

    KCvale Motorized Bicycle Vendor

    You need to tap a center hole in the end of the stud (not easy) to keep your drill bit square and not wandering to the side.
    Then just drill slow with some oil until you have enough to get the reverse thread tapered easyout bit to bite.
    Then just back it out slowly until you have enough stud out to grab it with pillars or something to finish the extraction job.

    Just a tip...
    DON'T USE ANYTHING BETWEEN THE ENGINE MOUNT AND FRAME!
    Your engine should be mounted so tight directly to the frame that you can hold the top bar with one hand, the motor head with the other, and push back and forth AS HARD AS YOU CAN and the engine should not budge AT ALL.

    In short you don't get rid of engine vibration with mount insulation, in fact you might find that an engine securely mounted to the frame works well if you do it right, for example getting back mount at a 90 to the seat post and then securing the front.
     
    Last edited: Dec 11, 2014
  16. mrbg

    mrbg Member

    Good info,my bike the motor is tight to the frame no plate w ubolt. On my nirve I had to use plate and ubolt or it'd make contact w sprocket. Who makes a motor mount kit, preferably with a block of hard rubber included.
     
  17. butre

    butre Well-Known Member

    the ones at bikebobber.com are pretty nice
     
  18. dotcom

    dotcom Member

    was able to drill it successfully but not extract it successfully. I cant get a good enough grip on the extractor reverse bit to reverse the bolt out. It seems I need a huge pair of jaw locking pliers or something that will tightly hold the reverse bit. Ive tried my medium size locking pliers, vice grips, electric drill but nothing has the grip on it
     
  19. KCvale

    KCvale Motorized Bicycle Vendor

    That's the downside of locktight, especially red if that's what you used.
     
  20. crassius

    crassius Well-Known Member

    too much work at getting those out can leave the metal of the cases so fatigued that it won't hold the new studs properly if one does get it out - that is the point at which the angle iron approach becomes necessary
     
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