well i messed up big time

Discussion in 'Motorized Bicycle General Discussion' started by dropleg, Sep 19, 2011.

  1. dropleg

    dropleg New Member

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    This bike has given me so many headaches. first of all new cns carbs dont work. mine never worked, i spent hours and hours trying to get it to work. ive done everything but bore out the jets. sorry but this stuff needs to work right out the box. got an nt and life got better. Also i replaced the throttle it came with(plastic junk broke so fast.
    the muffler kept falling off(threads where stripped). I tryed to re thread the bolts but it ended up making things worse. now i have a big hole that have messed up threading and the heliocoil wont work. looks like my only option is to get a new cylinder head. I am trying JB right now. I doubt it will work but im out of options. i dont think i can make the hole bigger safely. any suggestions.???
     
    #1 dropleg, Sep 19, 2011
    Last edited: Sep 19, 2011
  2. PerryP180

    PerryP180 New Member

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    Use bigger bolts. The holes in the muffler mount can be drilled larger.
     
  3. Al.Fisherman

    Al.Fisherman New Member

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    Don't bother with the JB..It won't work and will be a waste of time. As I've heard the CNS carb is a bunch of junk. I have one but not planing to even try it.
    As far as the studs...I have posted many times over and over a list of mobs I do as the engine is taken out or the box. But I guess hardly anyone reads the stickies.


    http://www.mediafire.com/?k14v8jfej4nj434
     
  4. dropleg

    dropleg New Member

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    ya, i replaced the spark plug and wire already. defiantly worth it. never thought of using locking nuts and replacing the studs. honestly at this point i'm about to buy i new cylinder head. only 25bucks. my gaskets should still be good. don't know how hard it is to install. looks simple enough. IS this the route i should take???
     
  5. wayne z

    wayne z New Member

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    You can re-use the head gaskets succesfuly one time, but you must turn them over so they will re-form and compress to the slight angle that is machined into the mating parts. .
     
  6. FarRider

    FarRider New Member

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    Im sorry, what part did you strip out? you keep saying "cylinder head" but the exhaust bolts to the cylinder its self (cylinder barrel or "jug").
    Take it easy, its not the end of the world.
    Take a few digital pics of the damaged area and post them here and Im sure we can figure out something.
    You just learned the first lesson with the china girl "HT" engines,
    The aluminum they are cast from isnt that strong.
    (im being kind here, truth is i think they are cast out of chinese beer cans)
    FR
     
  7. dropleg

    dropleg New Member

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    stripped out the threads on the exhaust. where the muffler mounts to the engine. the cylinder body is stripped, not the studs. ill try to get some pics but at the moment theres jb weld on it. im sure it will fall off soon so ill get u a pic(I put JB on before i started this thread, did it in desperation).
     
  8. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    The best fix for the stripped exaust holes would be 'Heli-coils'.
    After you've taken off the jug, you should plan on replacing all the gaskets. There are a few vendors who sell complete kits cheap.
     
  9. dropleg

    dropleg New Member

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    yeah, i found an extra head gasket that came with my kit. guess i just need a few more.
     
  10. bandito

    bandito New Member

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    Yea my subaru i'm always having to put gas in it from driving it so much, too much work. Should of been gassed up outta the box.
     
  11. FarRider

    FarRider New Member

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    Ok here we go....
    First off.... back away from the engine Sir... hands off the tools or slap dash fixes for the moment.
    I've had that very same problem, but as per usual, when I do it i do it right. I cracked off the exhaust ports right hand side.
    I snagged my stock muffler on a curb and CRACK! I had to peddle it all the way home, some 10 miles.
    I had to buy a new cylinder, but i had the first one welded up and drilled and tapped, so now i have a spare.

    Yours is not as badly damaged BUT there are a few things you need to watch out for.
    Depending on how badly the stud hole is stripped out dictates the severity of the repair, or if you really need to disassemble the top end.
    Disassembling the top end can be a little tricky, count on new base and head gaskets and you must be cautious about the piston rings, they must be orientated properly or the rings will snag on the ports and break.
    I use a double wide hose screw clamp to compress the rings for easy re assembly and to keep them in the right position.
    You dont want to pull the top end off if you dont have to.

    If its just stripped then you might be able to just use a helicoil insert of the appropriate size, these are available at most major auto parts stores, dont bother asking at Homedepot.
    Get more than one, to do both studs, get two of the right sized drill bits, the counter person at the auto parts store has a list of what size drill bit to use with which helicoil insert.
    Stuff a paper towel into the exhaust port to stop any metal shavings from getting in there.
    CAREFULLY drill out the stripped holes, go slowly and make sure you hold the drill perpendicular to the hole as not to miss drill it at an angle.
    If you cant hold the drill correctly because the frames in the way you'll have to pull the engine out of the frame.
    This is still easier than pulling the top end off.
    Post those picks and we can tell you what way to go with it.
    FR
     
  12. dropleg

    dropleg New Member

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    ok, but my helio coil didn't work. the hole is too big now. i don't know what my options are now. should i just bore it out to a 9 or 10 m and re bolt it? last time i used the drill i messed up my bike worse. Guess its worth a try.
     
  13. FarRider

    FarRider New Member

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    A helicoil didnt work? Thats a new one on me, I've been useing them for years on full sized motorcycle engines with no problems, but ok, no biggie.
    There are 2 options as i see it-
    #1- drill and tap it out to the next larger size CAREFULLY!
    #2- remove the cylinder, have the hole welded up and then drilled and re tapped for new studs.
    If you choose to go the next over sized route be careful not to drill to deep or at a bad angle it might breech the exhaust port or the cylinder its self or even crack the barrel altogether.
    At this point? id say screw it and buy a new cylinder, piston and rings from a reputeable dealer.
    But thats me.
    good luck
    FR
     
  14. dropleg

    dropleg New Member

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    helicoil wont work cause i made the holes too big. yeah i know, dumb on my part.
     
  15. tim turbo

    tim turbo Member

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    A quick question, is the exhaust supported properly?By that I mean with a bracket from the muffler to the bike frame. Just asking!
     
  16. dropleg

    dropleg New Member

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    no, no braket. i dont think my kit come with it
     
  17. Tom in Kingman

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    Looks like maybe it's MY turn to help somebody. When you fear that you cannot drill into something straight there is help. There is a tool you can make called a "Tapping Block". This is a flat piece of (usually) steel or block with a bit of thickness (usually 3 times the diameter) of that which it is to guide. A hole is drilled just a hair larger that the diameter of that which it will guide. EG: A 1/2 -20 tap will have a hole .500(one half inch) diameter so as to guide the tap straight into the hole. After about 5 or 6 turns you can come back out, remove the block and go back in knowing that your tap is running true.
    This will also work for your drill. You need a person with a drill press that will drill a hole the size you need perpendicular to the bottom of the block. Now with the block to guide you the drill will drill true. At a depth where you feel confident that the drill is running true you can remove the drill, remove the block and continue drilling to the desired depth. I keep a supply of these blocks for drilling and tapping in many sizes. You can use an aluminum block or thick plate but be careful that you don't wobble and "egg" the hole.
     
  18. Al.Fisherman

    Al.Fisherman New Member

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    Drilling the exhaust stud hole won't breach the exhaust port. If you drill a STRAIGHT hole, the drill will breach into the cylinder stud hole. Drill all the way through to the cylinder stud hole (only to the hole), tap for stud (I would use a regular tap followed by a bottom tap), and replace the exhaust stud after the cylinder is installed and torqued. The replacement stud will use the cylinder stud as the bottom of the hole.

    Here is a jig I made out of 2 X 4's
    [​IMG]

    [​IMG]

    The cut away are for 6mm screws to screw into the head to secure it when drilling.

    [​IMG]

    There are 3 mounting holes. This enables to drill either the exhaust or intake holes. The head can be flipped over and rotated 180 degrees. I don't remember the angle of the jig, but set head on the intake, and measure the exhaust angle.
     
    #18 Al.Fisherman, Sep 23, 2011
    Last edited: Sep 23, 2011
  19. dropleg

    dropleg New Member

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    this is all good information and i appreciate the help. but i lack the tools and equipment. i don't have a garage, i don't know anyone with a drill press. I think my best bet is to replace the head. Now i have never taken apart any engine in my life. but this looks like a good place to start considering how simple the engine is. im willing to spend 35 bucks on parts instead of a lot of tools i have no room for(I have a craftsmen socket and wrench set, that's about it). How hard is it to replace?
     
    #19 dropleg, Sep 24, 2011
    Last edited: Sep 24, 2011
  20. Mozenrath

    Mozenrath New Member

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    Replacing the head and/or cylinder jug would probably be the easiest, and possibly cheaper than getting a drill press for a hand drill and a bunch of other junk. Sounds what you're looking to replace is the cylinder jug. The head is the part that holds the spark plug that goes on top of the jug. It's not that hard to replace. You just have to use plyers to squeeze the piston rings so that the piston will slide into the new jug. It can be frustrating but its simple.

    When it comes to the engine and the muffler, don't waste your time with JB Weld. There's a time and a place for it but it doesn't hold well on parts that get extremely hot and vibrate rapidly.
     

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