Honda Sky SGX50 Crank Seals

Discussion in 'The Workshop' started by Del Sky, Feb 20, 2019.

  1. Del Sky

    Del Sky Active Member

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    Just bought another Honda Sky, initially to break for parts, however it's not in to bad condition....starts and runs, but leaking oil out of l/h side crankcase cover, which leads me to believe that the crank seals are u/s...….has anyone ever changed the seals on this model ?...….beginning to think I might re-build this donor machine instead......Del.
     
  2. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    Not done a sky, but plenty of sfx which are the same engine.
    I would change the crank bearings. Its a bit of a weak spot on those.
    Fairly straightforward job, you can do it in a day or a weekend if you take it slowly.
    The peugeot speedfight has a very similar engine, if you cant find pics of the Honda rebuild you will find pics of a pug.
     
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  3. Del Sky

    Del Sky Active Member

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    Thanks for that....I think it must be the seals, I can't see any other way that oil would get into crankcase, it is where the drivebelt is, so should run dry......
     
  4. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    Rear gearbox has oil in it.
     
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  5. Del Sky

    Del Sky Active Member

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    Mmmhhh…...good point, I think a closer inspection is in order......
     
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  6. Del Sky

    Del Sky Active Member

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    O.K....Just waiting for the new ignition switch to arrive, so that I can fire her up, as have taken the crankcase cover off, which contains the kickstart mechanism....if it IS the crank seals, and I suspect that it is, do I need any special tools ? like a drawer or something ?
     
  7. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    You can use a self tapper and pull the old one out, then a punch to push the new one in really carefully.
    Is the ignition switch the same as SFX as in 2 wires?
     
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  8. Del Sky

    Del Sky Active Member

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    Thanks for that.....no, the sgx has four wires, I can hot wire it, but would rather wait for new switch, I don't want to do any further damage to electrical system.
     
  9. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    Yeah I thought it was 4. I think the sfx is the exception. Ive only ever seen them with that type of switch.
    Hope it comes quick. Sometimes post takes forever.
     
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  10. Del Sky

    Del Sky Active Member

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    Just fired her up, and it has proved three things....1. the new ignition switch works 2. the lights work, and 3. as suspected, the crank seals need replacing......interesting times ahead...….
     

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  11. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    Thats a lot of oil. Did it smoke a lot?
     
  12. Del Sky

    Del Sky Active Member

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    Not really, although I have never had her at full revs....is there anything else that it could be ? besides the crank seals.....bearing in mind this thing has probably been stood for six or seven years, I suspect that the seals have dried out......
     
    Last edited: Feb 28, 2019
  13. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    Ah.
    The oil pump has leaked through, filled the crankcase with oil and then the crankcase pressure has blown the seals out.
    Guessing the oil bottle was empty.
     
  14. Del Sky

    Del Sky Active Member

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    Mmmhhh……...that could be the case, although when I got her the oil tank was nearly full, but who knows what someone has done in the past ?....first thing is to get to the l/h side seal, and see what's going on.
     
  15. Del Sky

    Del Sky Active Member

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    Thinking about it, it only leaks oil into the outer crankcase cover while it is running, it has been stood for over week, and on removing the cover it was completely dry.....gonna take the front pulley, and whatever is behind it off today, I may even get the seal out, before ordering the new one's.....here goes......
     
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  16. Del Sky

    Del Sky Active Member

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    That's made a start, but this starter ring gear is proving "challenging" to remove......there must be a special tool to remove it, I may be able to make one, I also notice that there is no square part, on the end of the crank, nor is there any hexagon for an allen key....how do you prevent the crank from turning while unscrewing the ring gear ? which I presume unscrews clockwise, against the turning cycle of the engine...….
     

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    Last edited: Mar 4, 2019
  17. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    You need heat, it is just pressed on if I recall
     
  18. Del Sky

    Del Sky Active Member

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    No....on this one it is threaded, sorry picture not very clear....
     
    Last edited: Mar 4, 2019
  19. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    Yeah, now I remember. I think its normal thread, just a tight fit.
    You need to hold the flywheel.
     
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  20. Del Sky

    Del Sky Active Member

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    Just been looking at the workings of an old 50cc SYM scooter engine, that someone gave me....the starter ring gear is on the OUTSIDE of the variator pulley, and is on splines......two minutes and you can get to the crank seals...the annoying thing is it is probably made by Honda as well.....
     

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