what are these engines made of?

Discussion in 'Motorized Bicycle General Discussion' started by motor-bike80, May 21, 2015.

  1. motor-bike80

    motor-bike80 New Member

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    hey guys, what are the china 66cc engines made of? is it aluminium? apart snapped off it and i want to epoxy it back on, its the part that the chain cover goes on from the engine, just above the drive sprocket. its no a big part but it has one of the holes for the longest screw of the clutch cover. so what are they made of? thanks
     
  2. dtv5403

    dtv5403 New Member

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    Chain jumped off the drive sprocket and broke the case, huh? Seen that happen once or twice. You should be fine to epoxy it back on, but I doubt it will be more than a cosmetic repair. Seen engines run fine without having the case repaired afterwards, though.
     
  3. Davezilla

    Davezilla New Member

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    They're cast aluminum, most likely recycled or a low grade alloy... epoxy wont be strong enough to repair that area but you could fix it with a few alumalloy rods and a propane torch.... but by the time you bought both, you could have purchased a new set of cases, then just swap out the broken half.
     
  4. Davezilla

    Davezilla New Member

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    Yup... I can agree with that... cosmetic repair yes, but structural no
     
  5. bairdco

    bairdco a guy who makes cool bikes

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    i've tried to alumiweld parts on these engines. it never sticks. or the parts melt. it's a very low grade alloy, probably made from collapsed corrugated roofs and beer cans, mixed with rocks and the sweat of chinese factory workers.
     
  6. motor-bike80

    motor-bike80 New Member

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    haha omg thats exatcly what happened, i cant belive you knew lol, well im thinking its a structural repair scince the part that broke off has a hole for the longest of the three screws that hold on the sprocket cover goes through. this cover is on the left side of the engine and its part of the bottom end, will be abosute wwast buy a bottom end just for that haha the clutch is working fine even with just 1 screw holding it on anyway, but i still wanna fix it
     
  7. dtv5403

    dtv5403 New Member

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    What I'm saying is, the epoxy will give you s cosmetic repair, but I would not expect that repair to hold structurally. Meaning, you can epoxy the broken part back on, but you won't be able to put the bolt through that holds the clutch arm cover to the case. But you willvstill have the other two bolts holding the clutch stm cover on, so you should be fine.
     
  8. motor-bike80

    motor-bike80 New Member

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    haha omg thats exatcly what happened, i cant belive you knew lol, well im thinking its a structural repair scince the part that broke off has a hole for the longest of the three screws that hold on the sprocket cover goes through. this cover is on the left side of the engine and its part of the bottom end, will be abosute wwast buy a bottom end just for that haha the clutch is working fine even with just 1 screw holding it on anyway, but i still wanna fix it
     
  9. xseler

    xseler Well-Known Member

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    Aussie/British ---- "Al-u-min-e-um"
    'merican ---- "loom-num"
     
  10. 2door

    2door Moderator
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    Something to keep in mind here. That 'cover' is part of the clutch actuator. When you disengage the clutch there is force applied to that part because the cam inside is depressing the bucking bar against the internal clutch spring. Holding it on with only two fasteners might work, for a while, but the chances are good the cover will crack eventually. Especially when the two fastners that are there are only toward the front leaving the rear section unsupported.
    Incidentially, that long bolt is there to attach the chain guard that comes with the kit.

    No glue is going to fix it. Like was suggested, the cost of a new case would probably be less than having it welded or buying the material to try it yourself.

    Proper chain tension will keep the same thing from happening again. A loose chain was the culprit. 1/2 to 3/4" slack is the recommended tension. More than that and you're asking for trouble.

    Tom
     
  11. dtv5403

    dtv5403 New Member

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    A buddy of mine had this happen to his first engine, a black 48cc skyhaek with the round head. It ran for over a year and that clutch arm cover never gave any issues. Rings gave out, but the clutch worked just fine snf the clutch arm cover was fine.
     
  12. fatdaddy

    fatdaddy New Member

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    Yer putting a LOT of pressure on the two screws and they will work loose or eventually strip out. You can ride it while yer waiting for yer new case to arrive. It should be OK for a short time. Sorry to give ya bad news, ya gotta order a case. 2door is right about the chain adjustment. I've seen a lot of busted cases over the years because of a loose chain.
    fatdaddy.usflg
     
  13. dtv5403

    dtv5403 New Member

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    I don't know, my buddy's engine ran fine that way, he had to tighten the screws down once or twice, but after that he just loctited them and that was that, ran it for over a year like that. At most I'd say buy the new case but wait until you actually have a problem to swap it out. Case swapping is no easy job for a beginner.
     
  14. fatdaddy

    fatdaddy New Member

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    And yer right bro, If it works, It works. call me a perfectionist If ya want, but I just cant run around showing off my bike with a busted case. And while changing a case aint the easiest job but what better way to learn? These are a very simple engine with only a crank and clutch arm to deal with. Once ya see it you just say AWWWW SHYIT, THATS EASY!!! Just don't forget the three screws under the clutch.
    fatdaddy.usflg
     
  15. maniac57

    maniac57 Old, Fat, and still faster than you

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    Someone here did a hub jackshaft that required him to cut the long screw completely off for chain clearance, and he simply drilled a new hole and used a long bolt and nut to clamp the cover.
    Sorry I cannot find the thread. It was a 3 spd hub used as a friction drive geared trans.
    I want to say it was Cannonball, but I cannot find a link


    EDIT: Found the thread! Cannonball's abbynormal 3 spd
    http://motorbicycling.com/showthread.php?t=58233
     
    #15 maniac57, May 21, 2015
    Last edited: May 21, 2015
  16. crassius

    crassius Well-Known Member

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    I had this once. I used a large steel washer that had inner hole that fit the curve of the case where the drive shaft runs thru. I cut a section out of it and ground the outside to match the rest of the motor. I then drill 3 holes in it thru the remaining case, and put 3 bolts thru with nuts on backside & upper left & center bolt heads ground down a bit to clear chain. A spacer just as thick as the broken piece of case to keep it straight when tightened left me with a working motor again that was even stronger than before since the steel part was a bit thicker than the original aluminum part.
     
  17. motor-bike80

    motor-bike80 New Member

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    i now have only 2 screws holing on the cover and i think it will be just fine, not worth buying a case anyway,
     
  18. kevyleven007

    kevyleven007 Active Member

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    Something else will probably break next week anyway. So, might want to go ahead and order a new kit now.
     
  19. indian22

    indian22 Well-Known Member

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    Lot of good advice given in previous posts.I suggest preventing future damage to you case and to your person. Chain failure isn't uncommon on two wheels for whatever reason breakage, link keeper loss, loose chain etc. First already suggested in previous post, proper chain tension, 2nd. lube well and often, 3rd. install link keeper correctly with closed end traveling in the same direction as the wheel, 4th. use the correct chain and buy quality. Last install a case saver & possibly your life saver as well. These (when properly installed) prevent chain to case lockup by threading the entire length of chain over the engine drive sprocket without binding into the engine case. Cost between $10. & $60. on E-bay & their easy to install using a hand drill & basic tools.

    I'm not a vendor though I show an example of one type mounted on my Indian Navaho bike. It's the more expensive type about $60. but I use a simpler version that should work just as well on another bike $10. or so.

    Unfortunately I lost a chain at about 25mph (keeper fell off, my fault) on the bike pictured with chain saver installed & never felt it, engine just kept reving as I slowed to a halt with the entire chain on the ground aboubt 30 yards behind me! Quite often the rider is ejected over the bars when chain to case lockup occurs at speed & both rider and engine are damaged. The case saver prevents both injury and engine damage. Some will advise otherwise to initially save a few bucks. 50 plus years riding motorcycles has convinced me to exercise caution. They might also think running non-reinforced fenders a good idea also, but one trip over the bars will convince them otherwise...if they survive. Rick C.
     
  20. indian22

    indian22 Well-Known Member

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    Case saver installed.
     

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