2 tires down, I must be doing something fundamentally wrong here...

Discussion in 'Motorized Bicycle General Discussion' started by lolitsdaelan, Jun 6, 2010.

  1. lolitsdaelan

    lolitsdaelan New Member

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    So I've totally mangled 2 rear tires, right at startup. I'll be pedaling the bike, get a decent speed going, drop the clutch, it puts for a few, then the tire pretty much collapses. I'm pretty sure whats happening is that the chain is falling off, getting caught in the spokes, and that locks the tire up and trashes it.

    I can only assume I'm not setting up the chain tensioner right. Does anybody on here not use it? If so how successful have you been? It seems like no matter what I do, the chain will inevitable fall off. Is there a problem with the sprocket?

    I'm just running out of ideas and out of motivation for this project. I don't get how people get these fired up in 4 hours =(.
     
  2. 2door

    2door Moderator
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    When you say "tire" do you mean the rim/spokes? I've never heard of a tire being ruined by a chain coming off.
    If you are trashing your rim then you have an alignment/tension issue with the drive chain, drive sprocket, tensioner and rear wheel sprocket. Yes, you can run without a chain tensioner, many have done it successfully IF you have a way of maintaining proper chain tension. That will be the rear wheel mounting, called drop outs, that allow you to move the rear wheel to adjust chain tension. Another deciding factor is if you have clearance between the chain and the bike frame. Use the search feature and read about chain tensioners. There is lots of information there and ways around the tensioner issue.
    Tom
     
  3. lolitsdaelan

    lolitsdaelan New Member

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    Do you think that I have the tension on the chain too high? I've checked the alignment of the drive sprocket and tire sprocket, and they seem to be pretty much spot on.

    How much tension/slack should the drive chain have? I'd like to here how people on the forum have theirs set up, as I don't fully trust the instructions that came with the engine.
     
    #3 lolitsdaelan, Jun 7, 2010
    Last edited: Jun 7, 2010
  4. Dave31

    Dave31 Moderator
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    I run 1/2 to 3/4" slack on the drive chain. I also use sheet metal screws in the tensioner and chain stay to keep it from twisting.

    If your chain keeps falling off, it's either got too much slack or your sprockets are not aligned or your tensioner is not aligned correctly with the chain and sprockets tossing off the chain.

    http://motorbicycling.com/f3/chain-tensioner-modification-764.html
     
  5. Dave31

    Dave31 Moderator
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    Whenever I assemble a bike, I always lift the rear pull the clutch and pedal the bike a bit, watch and listen to the chain. I also do this spinning the rear wheel backwards. If all looks okay, and I hear no popping. Then before I ever fire the motor I pedal the bike around a bit. If I have a problem with the chain, sprockets or tensioner. This will usually allow me to catch the problem before I go buzzing down the street at 30mph.
     
  6. mapbike

    mapbike Active Member

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    AMEN......!
     
  7. mapbike

    mapbike Active Member

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    AMEN......!
     
  8. lolitsdaelan

    lolitsdaelan New Member

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    How many people use the outer most rubber isolator? It seemed like it would push the sprocket out too far, maybe I need it?
     
  9. mapbike

    mapbike Active Member

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    If you dont use the rubber rag joint "isolator" on both inside and outside of the spokes you will trash the wheel very quickly, when those mounting bolts that go between the spokes are tightened up the spokes are squeezed down tight and mashed into the rubber mounting rings so when under pressure from the engine pulling on the sprocket, they act as one and the pressure is distributed equally between them, so each spoke carries the same load, this is where the strength of this type of set up comes from, if you are tightening the sprocket down against the spokes without the rubber ring being in between it and the spoke here-in lies your problem, get you a good wheel, set it up correctly by putting everything where it should be and make sure that the sprocket is centered on the wheel as it needs to be and you will be go to go provided you mount the tensioner correctly and do as it was mentioned above by fairracing31 and after you get it lined up drill through it and into the tube it is clamped on and put you a small sheet metal screw so that when you pop the clutch starting the engine the tensioner doesnt rotate in toward the spoke and cause you another wheel replacement or a quick trip over the handle bars. good luck, just think it all through and mount that sprocket right on the wheel and you sjould be good.
     
    #9 mapbike, Jun 7, 2010
    Last edited: Jun 7, 2010
  10. lolitsdaelan

    lolitsdaelan New Member

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    Cool, I'll have to pick up a new wheel, then decide whether I can do without the tensioner with my drop-outs, or mod the tensioner as needed.

    Thanks for all the help guys!
     
  11. Dougan

    Dougan New Member

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    The recommendation I've always heard is that the tension should be the same as the pedal chain tension. I have a single bike and had a tough time tuning my tension, and eventually found that my motor drive chain tension is WAY more than my pedal chain tension. Not sure if that helps or not.
     
  12. mapbike

    mapbike Active Member

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    You are very welcome, thats what we are all here for, we have all had questions on these bikes and we all just pitch in and help one another, heck I've had loads of help in the last few months since I started tinkering with these things, I wish someone with the skills woul dput together a simple to the point fool proof instruction thread that is set up to go straight to all newbies that join this forum, with simple to read illustrations and so many problems that the new people to this have could be avoided from the get go, I dont have the computer skills to do this but it would be a great tool to prevent accidents and many frustrations for the new guy to the motorized china made 2 smoke engine kits.

    good luck and just keep asking questions, it will save you lots of head aches
    Sincerely, Shan
     
  13. 2door

    2door Moderator
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    Just one more word of caution before you go any further. Every tensioner bracket I've seen requires a slight twist to get the tensioner wheel to align with the chain path. The chain stay, the part of the bike frame that the rear wheel and tensioner bracket mounts to is usually not parallel with the rear wheel. The tensioner bracket mounts to it and unless you add a slight twist to the tensioner bracket the tensioner wheel will not run true with the chain. Mount everything up and then stand back and look at things I think you'll see that the tensioner wheel is cocked slightly to the chain path. That must be corrected or you'll continue to wreck rear wheels/spokes. Also heed the advice above and secure the tensioner bracket to the bike frame so that it can not move (rotate) into the rear spokes. This situation is not uncommon; in fact it is probably the biggest cause of premature damage and failure of the first-time build.
    Tom
     
    #13 2door, Jun 7, 2010
    Last edited: Jun 7, 2010
  14. mapbike

    mapbike Active Member

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    2door is absolutely right about the tensioner not sitting in alignment when perfectly vertical, i have run into that problem on my bikes. good call on that one 2door I had forgot about it. just goes to show that no matter how much you mess with these things we can always overlook something that can get us in trouble, thats why we all need to take advantage of the wealth of knowledge on this great forum.

    This is off topic but I've got to say it anyway, I just think about all us guys and maybe a few gals that grace this forum each day or maybe just ever once and a while and I just cant help but think that here we are a fairly large number of people that for the most part dont even really know each other most have never met accept here, and wow just think of how we work together and lend a helping hand day after day giving advice and even at times sending $ funds to a fellow biking friend in need who has had a tragedy in their life, it really make me proud to be an American and to just think that over 200 years ago we as a people came from all over the world and help our fellow man with the same ambitions & desires to accomplish all that has been built in this nation, and yea we made some mistakes along the way that is the human condition of not being perfect but, look at how the rest of the entire world has benefited greatly from what we have been able to accomplish as for the most part God Fearing Honoring Red Blooded Americans that care about our fellow man and are willing to lend a hand and share the knowledge we have gained from our own experiences in life, that is what it really means to be an American in so many ways, we have poured more resources, medical aid and money into the rest of the world on a scale that no other country has ever even come close to matching and probably never will and most of them have existed 1000 years longer than we have and some even more, so to wrap this up I just want to say to everyone on this forum that everytime you help your fellow man on here you are carrying on a true American tradition that I truely hope never dies.

    God Bless & God Bless America
    Sincerely, Shan
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