I had a breakdown today...

Discussion in 'Motorized Bicycle General Discussion' started by CTripps, Nov 4, 2011.

  1. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    Cool, good to know. Just assembled my new Dremel workstation and have been playing with the toys that came with everything.. this afternoon I'll go check and see if I have a dry corner to work in in the garage. It's a rain day here, so maybe, maybe not.
     
  2. vincent713

    vincent713 New Member

    Joined:
    Jun 2, 2010
    Messages:
    287
    Likes Received:
    0
    Rotary tools are a MB's best friend. I couldn't live without it, I think every rider should have one in their tool box.
     
  3. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    My old rotary tool, a store-branded one, served me well for a long time. The collet is now seized, the flex shaft has jammed. It'll be useful until the grinding bit in it is gone, I guess. It proved it's worth though over the years, and is going to be nearly essential in the next little while so I decided to bite the bullet and invested in Dremel brand name stuff this time. A lot more expensive than the store one, but I know I can trust in the brand and the warranty. I spent a few hours trying to sort out and straighten up the mess I call a work area in the garage to make space for it.
     
  4. vincent713

    vincent713 New Member

    Joined:
    Jun 2, 2010
    Messages:
    287
    Likes Received:
    0
    Nice, I'm sure you'll put a lot of good use to it. I have my Craftsman for about 6 yrs now and still works like new. I need to get more bits though, trying to find something that can cut through steel tube.
     
  5. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    For cutting tube a brand new 24TPI hacksaw blade works well for me. I haven't tried cutting frames for custom builds (yet), but on seatposts and so on, it's like a hot knife through butter.
     
  6. Ibedayank

    Ibedayank New Member

    Joined:
    Oct 29, 2011
    Messages:
    1,171
    Likes Received:
    0
    hacksaw sawzall 41/2 grinder with cutoff wheel .... 14inch chopsaw just depends on how thick and how nice i want the cut
     
  7. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    Nice if you've got 'em. I'm on a limited budget, so I do the best I can with what I have, sometimes I just have to get a bit creative with things doing it.
     
  8. Ibedayank

    Ibedayank New Member

    Joined:
    Oct 29, 2011
    Messages:
    1,171
    Likes Received:
    0
    taken me many years to get the tools I have and many other people have much nicer stuff then i do cheaper tools may not be as nice but still get the job done
     
  9. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    So, with what I started this thread for resolved (for now), I have a new problem. I've mentioned it other places in passing, let me lay things out clearly here.

    Yesterday I went for a ride, and lost spark. I got it home and started testing things. I pulled the plug and rolled it with the plug on a head bolt. No spark, and the engine whut-whut's steadily rolling it. Finger in the plug hole, and it has compression.
    By running the other bike with the CDI from mine, I've pretty much eliminated the CDI, it worked (by the way, the wire and boot were replaced with NAPA parts months ago). I checked continuity on the wiring. On mine, blue checked out from tip to end, and past soldering point. Same for white and black. I get a circuit between the end of the black and pretty much everything else inside the housing, except the ends of blue and white. I did the same check on the second bike (that runs). The results were the same, except that the white wire also makes a circuit with everything else, same as the black, and from the end of the black to the white as well.
    Note, a while back I had to switch from black/black to white/black to my CDI as it stopped running then.

    So, today I went back to it. I replaced the magneto and the spark plug. There are a couple of marks on the white and blue wires of the old one where they were tight against the edge of the hole they go out of. I checked and each mark was a tiny break in the insulation on the wiring, even if it didn't look like it, so both may have been shorting against the housing. Wired up blue/blue and black/black, no killswitch with the replacement. Tried it a few times and it turns over, but nothing. I swapped to white/black and tried it a few more times and once it caught. The choke was open (lever down) and the throttle was half to full. I normally have to start with the choke closed first thing and can change it after a short wait. So anyway it ran when I kept it cranked open, and stalled out when I relaxed the throttle. It didn't want to restart right after that (and hasn't been tried since, the weather's gotten a lot worse in the last hour so I may not try again tonight).
    Just to be sure, I pulled the carb and went over it. Drained it, pulled it apart. The float is fine, the lever seems fine, stem and needle are good. The barrel lifts when the throttle's twisted. Put it back together (less the drain screw) and it dribbles fuel freely at the drainout with the valves open. (Between that and the wet plug I know fuel's getting through.) Cleaned out the 'air filter'/foam while it was apart, it looked a little wet and gritty. The needle setting hasn't changed, and the ilde adjust screw is still snug where it normally sits.

    So I'm back to no spark, and just about out of ideas. I'm back to work Monday, so I'd like to get it sorted out before then if I can. There must be something I've missed or overlooked. Fortunately I haven't sealed everything up yet so I can pull the cover and start again if I have to.
     
    #29 CTripps, Nov 11, 2011
    Last edited: Nov 11, 2011
  10. GearNut

    GearNut Active Member

    Joined:
    Aug 19, 2009
    Messages:
    5,105
    Likes Received:
    3
    The blue and white mag windings, while wound separately in relation to each other, have a common ground that is soldered to the mag frame.
    The black wire also grounds to the frame via a seperate eyelet soldered to it's end which is captured under one of the mag mounting screws.
    If you are getting continuity between the black wire end and everywhere on the engine including the mag frame then that indicates that the eyelet connection is good.

    It seems to me that the common ground for the windings that is soldered to the mag frame has failed.
     
  11. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    So I swapped to a new CDI, with a new wire and plug boot I put on it and hooked it all up, using the black from the engine, and I managed to get it running after a few minutes of trying. :) The problem is I had to hold the throttle open to keep it running. I set the idle screw to keep it going and put it up on the chainstay stand, and as soon as I let the clutch lever out it stalled with no load against it except the wheel. I also noticed that I can walk it with the clutch lever released and turn the motor with the plug in today, which is unusual. Without my weight on it that doesn't normally happen.

    So, now I'm wondering about compression loss. There's no mess (that I can see) around the head gasket so it's unlikely to be the problem. The next most probable culprit would have to be the rings, wouldn't it?
     
  12. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    So, I pulled the head and had a look, and I'm still not really sure what's up. Some of these shots are a little blurry, sorry 'bout that my hands aren't always steady.

    It looks like there might be a bit of a leak in the head gasket, on the exhaust side (first pic).
    102_2359.jpg

    The top of the gasket (second pic)

    102_2346.jpg

    Top of the jug and bottom of the head gasket (no idea which way around it was facing, it dropped and cartwheeled across the floor)

    102_2347.jpg

    Looking down the cylinder (more pics from other angles later)

    102_2348.jpg

    Top of the piston at top of stroke

    102_2353.jpg
     
  13. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    Going around the cylinder...

    Exhaust at left, intake to the right:

    102_2349.jpg

    Exhaust at top of pic, intake at bottom

    102_2350.jpg

    Intake on the left..

    102_2351.jpg

    And finally, intake at the top of the pic...

    102_2352.jpg
     
  14. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    Once more, with different lighting, same order:

    Intake @ right:

    102_2354.jpg

    .. @ bottom

    102_2358.jpg

    ... @ left

    102_2355.jpg

    .. and @ top:

    102_2356.jpg

    I don't see or feel any scoring, the streaks on the inside of the cylinder have no texture (and they smear). The piston moves smoothly with no squeaks or other noise.

    So, now I once again need to call upon those who know more than I.... Ideas folks?
     
  15. GearNut

    GearNut Active Member

    Joined:
    Aug 19, 2009
    Messages:
    5,105
    Likes Received:
    3
    I am stumped without being able to get my hands on the engine.
    Just looking at the photos I did see some things that I did not like. They could be nothing at all, but I circled them in red:

    It looks like a damaged transfer port and chips in the carbon and piston crown caused by something bouncing around in there. It really is hard to be definitive just by looking at these photos though.
     

    Attached Files:

  16. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    If there's anything I can do to make it easier besides beaming the motor to you, let me know.
     
  17. vincent713

    vincent713 New Member

    Joined:
    Jun 2, 2010
    Messages:
    287
    Likes Received:
    0
    Why don't you take the cylinder out and take a closer exam, it's pretty easy to take out. When you do, also check the piston and the rings.
     
  18. killercanuck

    killercanuck New Member

    Joined:
    Dec 17, 2009
    Messages:
    1,749
    Likes Received:
    0
    Aside from some foreign crud like GearNut pointed out(which may or may not have done any harming damage), it looks like you've had a substantial leak on your head gasket too.

    Look at your head-gasket seal from one side to the other, and the trail of leaking sludge out of the exhaust side:

    [​IMG]

    Your head and jug will need a good lapping.

    You should pull the jug to make sure theirs no nicks in your rings that match the groove that GearNut pointed out too.


    If you don't know what lapping is, get a wettable sheet of 300+ paper on a piece of glass(flattest surface readily available, don't use wood or steel, too many hidden imperfections) to lightly flatten out your mating surfaces. on the head, as well as the jug.

    Pro-Tip: the more you take off after a proper "true surface" only raises your compression, but don't go nuts your first time around.

    gl.
     
  19. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    I'll do that first tomorrow, as long as the angle of the rain changes. Right now there are about 3 leaks in the roof over my workspace, not what I want to have over an open motor. If the direction changes, they'll stop. :rolleyes:
     
  20. killercanuck

    killercanuck New Member

    Joined:
    Dec 17, 2009
    Messages:
    1,749
    Likes Received:
    0
    good thing grocery bags are still only a dime :p
     

Share This Page