Replacement rear engine mount

Discussion in 'Mounting Techniques for Bicycle Motors' started by rexfan10, Sep 17, 2012.

  1. rexfan10

    rexfan10 New Member

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    Hi, i had a strange noise coming from my bicycle engine the other day, and as i was making sure every nut and bolt was tight i came accross the fact that Part of my rear engine mount had come off/fell out. Its a little hard for me to explain and like they say: "a picture is worth a thousands words." So here ya go :
    [​IMG]
    ( sorry about it not being properly focused )
    Basically one of the threaded bolt things rattled its way loose and fell out the
    back. If somebody could tell me where i could buy one or what size the bolt and nut are, and how im to go about putting in the new one i would be much obliged. Thanks, Ruan brnot
     
  2. MotorBicycleRacing

    MotorBicycleRacing Active Member

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    Those threaded bolt thingies are called studs and the size is 6 mm 1.0

    Hopefully it didn't break off in the motor.
     
  3. rexfan10

    rexfan10 New Member

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    Hi, Thanks for the sizes. im afraid it has broken off in the motor :( do you have any tips on getting it out? Thanks, Ruan.
     
  4. MotorBicycleRacing

    MotorBicycleRacing Active Member

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    Do you have a pic of the broken off stud?
    is there any part of the stud sticking out or is it flush or even broken inside?

    Do NOT do anything in haste as you can make the problem much worse.
     
  5. rexfan10

    rexfan10 New Member

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    Hi, there is a tiny bit of it still sticking out, i might be able to clamp it with some pliers but am worried on clamping it so hard that it sort of squashes it leaving me with nothing to grip with. Heres a pic:

    [​IMG]

    You can see just how little of its exposed as you can only see one bit of the thread. Its also in a very awkward place so to get it out id have to take the engine right off the bike :( :-||
     
  6. MotorBicycleRacing

    MotorBicycleRacing Active Member

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    Did you use any loctite on the stud?

    Take the motor off the bike.

    There are a few ways to remove the stud depending on what tools
    you have .

    Do you have access to a welder?
    You can weld a stud or nut to the broken piece then unscrew it.

    Personally, I would file the broken end of the stud nice and flat.

    Center punch the middle of the stud very accurately.

    Drill a 1/8" hole making very sure it was centered and going in straight into the stud.

    Once you have the hole drilled try a larger bit then reverse the drill and sometimes
    the stud will come out.

    If not drill the hole larger so it is the right size for an EZ out.
    I find that the square EZ outs work the best.

    Be very careful when you turn the EZ out as they break off fairly easily
    and they are very hard steel so almost impossible to remove.

    The last option is to keep drilling all of the stud .out and re-tap the hole.
     
    #6 MotorBicycleRacing, Sep 17, 2012
    Last edited: Sep 17, 2012
  7. 2door

    2door Moderator
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    If you have a Dremel tool and a cut-off wheel for it you can grind a screwdriver slot in that stud and possibly back it out with a screwdriver. If you used Loctite on the threads,
    sorry but, good luck.

    Tom
     
  8. bairdco

    bairdco a guy who makes cool bikes

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    you can also buy left handed drill bits that are used to remove broken studs like that. they sell them at Harbor Freight for pretty cheap, but i dunno how easy they are to get in scotland.

    the tip above from tom is what i'd try first.
     
  9. rexfan10

    rexfan10 New Member

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    Hi. The engine came with the studs in so i am unsure wether the seller/manufacturar used loctite on them. Im also afraid i have no access to a welder, punch or dremel :( I was going to try using theese clamp/plier things we have, and if that failed go to a very mechanically knowledged friend of mine who does have a grinder, and probably every other tool mentioned above. Thanks for your help, Ruan.
     
  10. JonnyR

    JonnyR New Member

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    the best way to take it out is with the easy out mentioned above
     
  11. rexfan10

    rexfan10 New Member

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    Hi all, i have some good and very bad news, i managed to disconnect everything from the engine, take it off the frame and replace the studs. However i noticed a loud rasp from the exhaust which sounded bad and it turns out the rubber seal that goes between the exhaust and engine fell apart, but thats not the worst part. The chain tensioner came loose, fell to the side and ripped out half the spokes :( so ill ned to get a new back wheel, which shouldnt be to hard, but im not sure where i can purchase a new rubber seal. If anybody couldnt possibly give me a link to a uk website that sells theese rubber seals i would very much appreciate it.

    PS. are they called rubber gaskets? I was a bit reluctant to ask incase i was wrong and i looked stupid, but im sure knowing the correct name would help me in my quest of finding a new one. Thanks. :-||
     
  12. Moto

    Moto New Member

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    Great that you got the stud out! Bummer about the spokes... Thats what you get when you use the stock chain tensioner. Here is a thread with some alternatives... http://motorbicycling.com/showthread.php?t=2063 (there are also many upgraded chain tensioners you can buy that WILL NOT fall into the spokes) Heres a link to a place were you can get an exhaust gasket (thats what there called) just scroll down a little its about 3/4 down the page. http://www.transformercycles.com/parts.html Good luck dont give up moto
     
  13. rexfan10

    rexfan10 New Member

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    Hi, thanks for the links. Thanksfully a new guy has just moved into the house below us and he is mad about mountain/road biking so he is going to replace the spokes for me :) Ill definately be buying a new gasket and probably a new better chain tensioner as i think the cheap one got bent when it got caught in the wheel. I think i'd have to break a few bones before i would even consider giving up on my motorbicycle, its way too much fun :)
    Thanks for all your help, Ruan.
     
  14. nightcruiser

    nightcruiser New Member

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    I just did away with the chain tensioner all together and never looked back, been riding like that for 2 years now and love it. The tensioner is bogus, it makes a lot of noise, adds a lot of drag, and tends to take out rear wheels like what happened to you. Lucky you weren't seriously hurt...
    You would need to shorten the chain and see if you can get proper tension on the chain without the tensioner and verify that it wont rub on the frame or anywhere else without the tensioner. Mine didn't interfere but was a tad slack so I put a small shim between the motor and the rear motor mount and that tightened it up perfect. 1/2 links are also available for the chains if you want to go that direction.
    Speaking of chains, I upgraded to a #41 which is a serious chain, bigger and stronger than the chain that comes with the kit. It's also harder to break and mend the links, so when I was sizing the chain up to run without the tensioner I used the cheap kit chain. When I got the cheap chain to the right size I counted the links and then made my #41 chain have the same number of links.
    The bike rolls so smoothly without the tensioner, it's quiet and the resistance when pedaling with the motor off is way less. It rides more like a regular bike now. I've put over 1,000 miles on this way and my chain is still perfect and tight. Some people say you'll need a tensioner because your chain will stretch, the KIT chain WILL stretch, a cheap bicycle chain will probably stretch too, but this #41 farm/industrial chain is pre-stretched and its not stretching any more from the force of running on the bike....
     
  15. Donavan321

    Donavan321 New Member

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    I agree, the stock rubber bands I mean chains aren't any good. I try to run 41 roller chain on all of my builds! Sometimes....I admit I will stick with the stock 415 with NO problems!
     

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