Infernal Machine - Help

Discussion in 'Motorized Bicycle General Discussion' started by Whiteride, Aug 8, 2015.

  1. Whiteride

    Whiteride New Member

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    Hoping there might be someone who is knowledgeable and familiar with this issue... The infernal machine was purchased used and is a four year old build. It ran great up to this year when it began to get fussy starting, loosing power and then starting ok but not wanting to run. I went through it and as everything fuel/air seemed good, I decided to change out the Mag and CDI. It has the same problems and I'm thinking the problem may be engine related. As mentioned it will start, but the cylinder gets instantly hot. It will stall out after a few seconds. On a test ride it runs poorly then buck and quits and the rear wheel locks up with the clutch out. It also has started to smoke which I put down to oil mix, but I'm thinking this may indicate rings? I pulled the top of the cylinder and the piston and walls look clean and smooth. I've also checked for movement by turning the mag magnet bolt and it turns then seems to become more difficult then smooth again? This procedure can not be done by rolling or turning the wheel by hand. As it is a 49cc, I'm wondering if it might just be simpler to replace the motor vs dicking around with repairing or rebuilding an motor that is getting hard to find anymore. This bike is incredibly fun to ride when it does run, but a heartbreaking little money pit.
     
  2. crassius

    crassius Well-Known Member

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    excess smoke is usually due to fuel in bottom of motor, or sometimes collected in cap of muffler - one typically just runs it a while to blow it out

    if muffler is clogged by burned oil, it can be loosened just a bit at cylinder and tested to see if power returns, if so replace or clean out muffler

    check for oil residue around head gasket and case seams for compression loss - tighten as needed
     
  3. 2door

    2door Moderator
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    Crassius covered much of what you need to check but I'll ask a couple of questions.

    What fuel to oil ratio are you using? We've found that the recommended 16:1 is too much oil. You can safely run 24:1 or better yet, 32:1. The high oil content can be a cause of exhaust clogging.

    How does the spark plug look? Dry or wet and oily? What color is the porcelain at the tip? And how are the electrodes and what plug gap are you using?

    Have you checked the air filter? They need periodic cleaning.

    If the rings and cylinder wall looks good, no gouges or scrapes, then I would be suspicious of the head gasket. The fasteners are notorious for loosening and allowing compression loss. We always suggect replacing the chrome acorn nuts with hex nuts. The acorns can bottom out and keep the cylinder head from seating well against the cylinder and gasket.

    Let us know if any of our suggestions help.

    Tom
     
  4. Whiteride

    Whiteride New Member

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    Thanks, all good tips, but I've ruled them all out.

    The core problem is in the complete power loss followed up by lockup or seizing. With the price of a new engine vs rebuild or further repairs it might be better to just replace the entire engine.

    With over $950.00 already invested I am reluctant to get in much deeper and am thinking of just selling it.
     
    #4 Whiteride, Aug 9, 2015
    Last edited: Aug 9, 2015
  5. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Try a NEW plug, and find the air leak. Getting hot would indicate a lean condition/air leak, somewhere.
     
    #5 Bikeguy Joe, Aug 9, 2015
    Last edited: Aug 9, 2015
  6. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    What kind of engine is this?
     
  7. Whiteride

    Whiteride New Member

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    Not sure of the Make, it came with the bike. I think it's a 49cc China Girl type. My concern is the difficulty in turning it over and the way it locks up when running. I can't see these as signs of an air leak? It seem more major.
     
  8. Whiteride

    Whiteride New Member

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    When it slows it feels like it running out of fuel, but that's not the issue, just how it feels, it just powers down like it suddenly hits a steep grade. Then it locks or seizes and won't turn at all. When it cools it will turn over but with difficulty. I've tried turning it at the magneto but it doesn't turn easily even with the plug and muffler removed. It cycles a few times easily, then seems to meet resistance then turns easily...
     
  9. tooljunkie

    tooljunkie Member

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    May want to consider pulling flywheel and make sure key and keyways are intact. No unusual noises makes me wonder if its a timing issue.
     
  10. crassius

    crassius Well-Known Member

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    re-reading your first - I wonder about 'locking wheel with clutch out' - this is usually a chain, wheel, or drive shaft problem rather than a motor problem
     
  11. Whiteride

    Whiteride New Member

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    TJ, Would it fire at all if that were the case? I changed out the CDI and the Mag and installed that with the piston top centre as I could not remove the nut securing the magnet, which I think is right. The only odd thing I found was a small coil spring on the floor which may or may not have come from the bike? I really haven't got the place to do repairs, so not way to really pull it apart. Kitchen floor doesn't really work well as a shop. I'm guessing as no one seem to have any clear Idea of the problem, my best option is to sell the bike as non-running, or get another motor ready to bolt in. I'm getting kind of tired of throwing more and more money at this project that's running about $500.00 an hour to ride so far, and that's not counting fuel or labor. ;-)
     
  12. Whiteride

    Whiteride New Member

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    Crassius, With clutch in the chain rolls freely. Either way I guess I'm at the stage I will have to remove the motor and get it torn down and see if there's anything obvious. Of course if I do that I'll have to consider reassembling it with a repair kit, or just put a new motor on it.
     
  13. crassius

    crassius Well-Known Member

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    a small coil spring sits inside the spark plug cap if you have the plastic cap - if that comes out, the cap is dead - as a temp fix, one can strip back the plug wire a bit and fasten it to plug with a small nut
     
  14. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    If it has an air leak or is running lean for some reason, it will tighten up, (loose power) and then seize. Just guessing of course.
     
  15. Whiteride

    Whiteride New Member

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    Well I'm beginning to think it is simply not worth attempting to delve too far into a 49cc. Seems parts and availability are an issue. I can get factory new 66cc for around $130.00 which would seemingly resovle my problems and give me a fresh more powerful bike I'll simply decal as a 49cc.
     
  16. Whiteride

    Whiteride New Member

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    Already upgraded the POS with a silicone wire and automotive end. The stock cap fit way loose and broke almost the moment I put it on.
     
    #16 Whiteride, Aug 10, 2015
    Last edited: Aug 10, 2015
  17. Whiteride

    Whiteride New Member

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    WTF? Pulled everything apart down to the lower case and so far everything looks like new? Be interesting to see what's up when I pull the case apart...
     

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