has this happend to you

Discussion in 'General Questions' started by minibiker, Oct 8, 2007.

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  1. minibiker

    minibiker Guest

    my brother and i went riding yesterday (he has a dax 70/80 hes not into the forum hed rather me do all the work for him) but we were cruising at about 30 and i look back to see him staring at something i turned around and when i got there i realized his engine fell out!!! the head of the mount bolt that went thru the frame sheared clean off. it was bent at about a 45 degree angle, the chain was bent and stuck behind the drive sprocket i had to pull the sprocket off the case. the hard part was getting the rest of the mount bolt out becuz it was just the head that came off i coulnt pull the engine up cuz it didnt have enough clearence so a had to cut it with a dremel and it came out. but i was just wondering if any one else has had that problem

  2. spunout

    spunout Member

    no, minibiker. i can probably speak for the rest of the entire world, when i say thats never happened to anyone else. ever.
    perhaps nothing was tight. its very important to make sure your nuts, bolts, and screws are tight. a pre-ride inspection may have taken care of that.
    did the motor survive?
  3. DougC

    DougC Guest

    I don't have a Chinese kit--but for my GEBE custom setup, I have an infatuation with nylock nuts.

    It's gotten to the point that I will only buy regular non-locking nuts when I know that a nylock nut won't fit or otherwise work (such as, loads on both sides of the nut)....
  4. japat100

    japat100 Guest

    vibration is a killer ,,

    if there is any one thing that would help improve these motors is proper motor mounts ,,, set in rubber ,, vibration is a killer ,it destroys everything ,yes even light bulbs and switches .. it seems that everyone including myself keeps giving advice on how to keep your nuts tight ,, lock nuts ,lock tight ,better bolts etc. about 90 percent of all our problems is caused by vibration and yet very little discussion on motor mounts set in rubber ,, we live with vibration and somehow we think its the norm ..and i don"t see anything or any co. making even a try at improving mounts for 2 cycle kits ,, theres got to be something better .
    vibration should be the no.1 topic on this forum until we find a answer ,or get some co. to make proper mounts ,and i would not be surprise that a motor set in rubber may get 20,000 or 30 ,000 miles before it burns out no matter what kind of oil you use ,, power saws 30 years ago wide open ,used every day would last 5 years ,i would say that is equal to 200,000 miles ,if not more , and they used any 2 cycle oil ,, so why so much discussion about oils when we should be talking about vibration ,,

    not only will your motor fall off ,, a neighbor took my bike for a ride and he had to go back walking to find his faults teeth ,, yes the vibration through his faults teeth right out of his head ,,i suggested to him the next time he takes the bike for a ride he best use lock tight the red tube , on his teeth ,, he did not think it was funny ,, o well no sense of humor

  5. bamabikeguy

    bamabikeguy Active Member


    My nomination for "augiesputtering coffee on the screen" post of the morning !
  6. gone_fishin

    gone_fishin Guest

    you were almost dead-on! :lol:

    my opinion about vibration: these lil happy-times have no counterbalancing on the crank...allowing more motion ("correct" motor-mounting) will result in an amplified vibration. best to lock it down tight and let the frame absorb as much as it's bulk allows, then deal with the rest by properly mounting everything else on the bicycle.

    an on-topic BTW-i ran my first 70 for 8 months and approx. 2500 miles (including my all-day 165mi affair) on all-original hardware...never lost one nut or broke one stud...proper install and diligent maintenance are the only reasons i have to explain it. that engine sits in a box waiting for a new home, and i'm sure it'll easily put out another 2500 miles.
  7. drimpact

    drimpact Member

    I keep a 10mm wrench in my back pocket when I ride. Before I ride I check everything (Preflight), When I stop to take a break, I allow the motor to cool down then check everything (in-flight). When I get home I let the beast cool down and check all the nuts and bolts (post-flight).

    Vibrations are a killer, but with my trusty 10mm in hand we are up to the task. I have found the motor mounts to be the most susceptible to loosening, During my checks I make sure they are tight. Early on in my motored bike days I learned the hard way about the ever loosening nuts and studs and had a similar motor mount failure. Since my pre, in, and post checks were put in place I have not had near the problems. It is easier to tighten something than try to find it or its replacement after it has fallen out.

    minibiker, don't feel bad about it, take it as a lesson and check, double check, then check it again when you get home. Its all a part of riding a happy times.
  8. atcspaul

    atcspaul Guest

    i did not drill thru my frame. i figured 2 bolts were better then one. bought an extra clamp at automotive store. took out the 6mm theads and changed them to 1/4 after i taped the hole and bought a length of threaded rod and cut to length and around that i used steel hollow tube close to the same size for strength. i also used permentant locktite on those bolts and not removable. with heat you can remove the perment ones. i am aproaching 400 miles which i may hit today if not i will tomorow and never had to touch my mounting screws. every other screw yes lol
  9. japat100

    japat100 Guest

  10. atcspaul

    atcspaul Guest

    i have rubber strips around each mount. i think hard rubber would worry me. between heat from motor, dripping gas and everything else they would not last long and dry rot. i may be wrong but that is my thoughts
  11. gone_fishin

    gone_fishin Guest

  12. japat100

    japat100 Guest

    broken hardware

    ,broken bolts ,motor falling off , lights bulbs failure , air leaks .muffler rattles , rubbers falling off the handle bar ,alum. frame cracks ,, are cause by vibration ,,, so the question is which is the best way to fix it ,, fix ever thing on the bike so it can take the vibration,,, or fix the vibration ??

    my opinion is fix the vibration if there is away ,, now you have just prevented broken hardware .
  13. gone_fishin

    gone_fishin Guest

    ok, so you're obsessed LOL! :p

    off-topic is anytime you ignore the original poster and get into your own thing...open debate with me about moderation is usually a losing gambit, best to just get on with whatever...meantime i'll take my year of experience with over a dozen installs and go with what i already know works...if you come up with a solution, we're all ears.

    minibiker, accept my apology for the OT debate, i'm pretty sure the engine didn't vibrate all the way off, it had to be misalignment (bent/stressed stud/bolt which broke...ask cruzin about misalignment) or something.
  14. japat100

    japat100 Guest

    ,the topic is that his motor fell off, so the mounting bolts must have come out ,or they broke off ,, and i am sure with your experience with these motors that you believe it is in part to do with vibration , no not many motors fall off most are caught before they get to that stage ,, many posts talk about bolts breaking off and they catch it in time ,,

    i understand that talking motor mounts on this thread would be off topic s and i except blame for being off topic ,but your reply on motor mounts and vibration was important ,i looked under the threads you recommenced ,but there was not much there ,, so i will bump it up and i hope you will give some input there

    ,, japat
  15. gone_fishin

    gone_fishin Guest

    ok...this got outta hand...i'm distracted by something elsewhere on the board.

    here's the deal...the reason that vibration is not very well covered here is because everyone eventually (and reluctantly) realizes there's no way out, the things are real buzzers and have to be locked down tight to be stable.

    mini's problem, i believe, is directly related to a misaligned hole for the front mount, it's tricky to get it just right. i think that when the back mount was tightened down, it drew the engine into it's proper position and stressed the front bolt, maybe only by a coupla degrees or a millimeter or two, but that will be enough over time and under load.

    so, if you do want to tackle it...i regret my discouraging tone and now i say "please start a new project-topic about a new mount design, i'd love to see you come up with something that works."
  16. japat100

    japat100 Guest

    i'd love to see you come up with something that works."[/QUOTE]

    thank you auge ,
    ,i have something started as we talk and if it works out good i will make a even trade for your lighting system .

    thats a fare deal
  17. gone_fishin

    gone_fishin Guest

    nu-unh! i love my light! i'll just copy your design & "allow" you to copy my light system ;)

    minibiker, now that we're back on track, did you ever find any evidence to help you figure the problem out?
  18. minibiker

    minibiker Guest

    no the mount was tight i checked that before we left i just put a new head gasket in it cuz he blew an old and i always double check the bolts after i do something im gessin the thing was just too stressed and broke. half way through the ride he looked every thing over and he said it was there but im not so sure about that
  19. Alaskavan

    Alaskavan Guest

    never mind.
    Last edited by a moderator: Oct 9, 2007
  20. Butch

    Butch Guest

    The same thing happened to me last summer. I was about 15 miles from home and pedaling pretty fast along with the motor when my crank loosened up enough to cause a pedal to hit the motor and break off the front motor mount bolt. When I stopped the motor was sitting sideways on the bike. Luckily I was able to straighten out the motor so I was able to pedal home.
    This was my first ride on this particular bike and I never bothered to check the crank for tightness. Live and learn I guess. Check everything for tightness even on a new bike.