URGENT - Crank Small Gear HELP

Discussion in 'Motorized Bicycle General Discussion' started by sniperxfire, Sep 24, 2013.

  1. sniperxfire

    sniperxfire New Member

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    So im planning to change my chain.

    I opened up my crank cover and found this.

    http://i40.tinypic.com/16iw3nm.jpg

    The small gear is sticking out as well as the screw. The end of the screw is kinda messed up but i think i can still use it. However i cant seem to push back the small gear to its original position. Its not loose and its very tight.


    I also noticed that the engine sprocket where you use the sparkplug to turn it is also loose. So i tightened that.

    Im still worried about the small gear being out of place.

    Any response would be appreciated.
     
  2. mapbike

    mapbike Active Member

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    Its common for that gear to set out a bit farther like yours is, what I would do is get you some blue thread locker (loctite) or equivalent, go ahead and remove that screw, put a few drops of the loctite on it and then put it back nice a tight, let it sit over night and you should be good to go.

    Map
    reddd
     
  3. Pluto

    Pluto New Member

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    Map, what would you do with this one?

    [​IMG]

    Came like this, brand new motor.
     
  4. sniperxfire

    sniperxfire New Member

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    Cool, i was a little bit worried about that.

    Yeh i also thought of using the blue loctite. Ill get it tomorrow.

    Thank you so much for your response once again.
     
  5. mapbike

    mapbike Active Member

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    wow... that is a bad one although most all of them do stick a bit I think that is the worst one I've personally seen.

    There's more than one way to make that one a bit better but each of the things I can think of are a bit hard to explain by just typing it out here on the computer, but I'll try my best to make a mental picture of what I'm thinking so you can follow me here, you may know exactly what I'm talking about but if not I'll try to explain by pix that I can take tomorrow that may help.

    OK, first you will need to pull the small gear off of the crankshaft, be careful not to loose the small woodruff key, you will need some 180-220 grit emery cloth sandpaper, remove the mag cover on the other side and remove the spark plug, before I go any farther here, you will need the correct puller to get that gear off the shaft, some kits come with the puller and some don't, if you don't have one order one and dont take anything apart until you have it.

    Now back on track, once you get spark plug out, mag cover off, clutch cover off, and the gear pulled off of shaft you will notice that the crankshaft is tapered, look to see if there is a bur on that taper that may be preventing the gear from seating all the way up as far as it should, if there is forget the sandpaper and get a fine to medium Flat bastard File and file the bur down flush maintaining the taper angle on the shaft as you file the high spot down, if there isn't a bur on the shaft it may be that the taper area was not turned down enough and that is why the gear will not go on the shaft as far as it needs to go, if this is the case then now is the time to get the emery cloth sandpaper, tear off an 8-10" piece from the roll, put it around the shaft so that you are holding one end of it between the fingers on one hand and the other end between the fingers with the other hand and while making sure that you maintain the correct angle you can start to use kind of a push pull motion back and forth with the sandpaper as it is wrapped in a horseshoe configuration around the shaft, the purpose of the spark plug being removed is so you can sand back and forth a few times and then you will want to rotate the engine so that its easy to equally sand around the shaft and not just in one place, just reach over and use the Flywheel/magnet to rotate the engine, just sand about 12-15 strokes and then rotate shaft 180 degrees/ half a turn and repeat, do this 8-10 times and then wipe of the shaft and just by hand ad hold the gear onto the shaft and see if it is going further up on the shaft until you get it to slide up about 1/8" further than it was before and then I would call it good. the gears dont have to be perfectly even for it to work just fine, perfectly even is great but none of mine are an I have not ever had an issue with them.

    Another method would be to tare engine down, pull the crank and chuck it up in a lathe with the connecting rod attached to a piece of surgical tubing and attached to a stationary source so that the rod would not swing around and create major trouble when the lathe was running.

    Another way that it could be done which may raise a couple eye brows here when I say this...LOL!
    Would be to have a friend around because it will take two people to do this method.

    if you have a drill that has a 1/2'' chuck you could have a buddy chuck the drill up on the flywheel nut, the spark plug will need to be removed for this also, spray a dab of lubricant into cylinder by way of the spark plug hole and have your friend run the drill at a medium speed while you hold the sandpaper or the file against the shaft again at the proper angle, the material will get removed much quicker this way so you will not want to wait very long bewteen times that you hold gear on shaft to check to see how it is fitting, if you remove to much material you may need to deepen the key way or at least file a little material off the bottom side of the woodruff key so it will allow the gear to be installed back on the shaft, don't spray a butt load of lube down in cylinder but dont run it very long in between giving it a quick spray to make sure the rings dont get dry against the cylinder wall.

    Well, Pluto I hope you can follow what I tried my best to explain here, if you have a question just ask and I'll do my best to clear something up.

    best wishes

    Map
    reddd
     
  6. mapbike

    mapbike Active Member

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    You're very welcome and I hope you get it fixed up just right and it is a problem solved.

    Map
    reddd
     
  7. maniac57

    maniac57 Old, Fat, and still faster than you

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    There is a woodruff key that can bind up and hold the gear out like this. If it is not fully seated and you run the bike, you could damage the crankshaft severely!
    Take the gear all the way off and be sure the key is properly installed in the keyway.
     
  8. Pluto

    Pluto New Member

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    Wow Great explanations. I did follow you Map and thanks. I will have a go at it in the morning. That is if the vendor does not make good on replacing it as I have requested. Not counting on that though.

    Manac, I hope you are right and just the key. Seems that to be easier than turning it down.

    You know it is a shame to get a motor like this. I did not purchase the cheapest one I could find. I went with one of the vendors from this site as I figured that would be a safe bet to a quality kit. Since this is only the second, or third as I purchased two from this Co., I am really disappointed. I did not expect perfection but at least a kit that would run.

    O well chalk it up as tuition. Seems Though that I am paying a lot of tuition for this hobby. Shoulda gone to Devry.LOL...

    Thanks again and I will let you know how it turns out. No pun intended.
     
  9. mapbike

    mapbike Active Member

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    Best of luck with it Pluto, Hope you have it flying like a Horse in no time flat.

    Map
    .wee.
     
  10. chainmaker

    chainmaker New Member

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    Yeah check the woodruff key on the second pic. See of the gear will go on without the key being in place, if it does there is your problem. Sometimes the gear pushes the key at an angle and it binds up. a little bevel filed on the top of the key will help.
     
    #10 chainmaker, Sep 25, 2013
    Last edited: Sep 25, 2013
  11. mapbike

    mapbike Active Member

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    Ditto........................!

    Map
    .wee.
     
  12. Pluto

    Pluto New Member

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    Well some news.

    Since I decided last night to write this motor off as a learning experience, I decided to give it one more shot. A real shot. I put the mag side crank back on the anvil and beat the gear real good. I got it in to what looks like a minimal accepted position. BikeBeery also left out the springs on both motors that keep the clutch pieces apart. So I scavenged a spring outta my junk drawer and put all together. It runs...

    Still lots of tweaking to do but I put a mile or two on it while playing with the carb. Not a recommended practice in Chicago traffic.

    So I guess we will see.

    Thanks again for all the replies and help. Who knows pretty soon I may know what I am doing. Na....

    BikeBerry still sucks...
     
    #12 Pluto, Sep 25, 2013
    Last edited: Sep 25, 2013
  13. mapbike

    mapbike Active Member

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    Glad to hear you got it going Pluto, hope it makes a good one.

    Map
    reddd
     
  14. maniac57

    maniac57 Old, Fat, and still faster than you

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    Beating the gear on is a bad way to fix a simple problem.
    Even replacing the gear and key won't cost more than a few bucks...
    A mangled crank keyway will run a lot more.
     
  15. Pluto

    Pluto New Member

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    Ya, I know I was just taking out some frustration. I had already made that motor a candidate for my first rebuild. I had ruined the seal the night before when I stupidly heated the gear trying to get it off without a puller.

    I had purchased two and fixed the second one properly. It will be fun to tear this one down and rebuild it.

    Thanks to all you guys for showing me how to fix it...
     
  16. mapbike

    mapbike Active Member

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    Carry on and bes wishes.......

    Map
     

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