Engine stuck/ Piston not moving

Discussion in 'General Questions' started by RollingStones, Jul 18, 2014.

  1. RollingStones

    RollingStones Member

    Hello eerbody,

    So I took apart the top end of my engine so I could clean it and the piston and once I put it back on I was able to get it running for a few yards until it came to a halting screeching stop.

    I realized that the bike would ride when I had the clutch pressed but as soon as I let go it would stop and the engine would be stuck.

    I took it apart again and realized that the arm that connects to the piston which makes it go up and down is stuck and the rotating parts of the engine will not rotate.

    Something may have fallen in there while I was monkeying with the piston and I didn't see.

    My question is, how can I troubleshoot this to see where the issue may be coming from? is there a video anyone can point me to on taking apart the bottom end of the engine and troubleshooting for engine rotation issues?

    Thanks for your help in advance.


  2. crassius

    crassius Well-Known Member

    there's a set of those pics on this board

    no troubleshoot needed - you got a piece of debris caught in your mains
  3. dougsr.874

    dougsr.874 Active Member

    You say you took it apart again...what does that mean??? If you haven't pulled the cylinder off the piston you need to do that first to make sure the cyld. wall & piston are not pitted & ruined....If those items are good the only other thing to do is what's called splitting the case.....that's a major undertaking. you will need a gear puller, a large screwdriver. a gasket set or sealent, and a lot of time and infinite patience...depending upon your mechanical ability, sometimes replacing the entire engine is a better option...If the piston or cylinder is bad and you don't find what caused it you still need to split the case.
  4. RollingStones

    RollingStones Member

    so do I basically take the whole thing apart and attempt to get whatever is in there out?

    Ive never taken it apart further then the piston so I am a little nervous about doing so.
  5. RollingStones

    RollingStones Member

    I just meant the engine head and piston. the piston looks pretty Fxxxed up now yea. Im moving out of state and the movers come to grab my stuff 7/23 so I doubt ill have the time to go through all that trouble. I'm thinking of just striping the engine apart so I have extra parts if needed in the future and riding it as a regular beach cruiser until I just buy a new engine....
  6. Fabian

    Fabian Well-Known Member

    It's one huge f*#kup. You now have to take the whole engine apart to install a new crankshaft.

    If you have f*#ked up the engine just by taking the cylinder off, i can't begin to imagine the f*^kup that will be created when you attempt to install a new crankshaft.

    It might be best to simply purchase a replacement engine.
  7. Big Red

    Big Red Active Member

    To do a proper top end rebuild cost me $70 or $80 bucks last time I did it, An ENGINE ONLY is $100, Trust me, Its worth the extra 20 or 30 bucks to just order a new engine, And you have spare parts.
    Big Red.
  8. crassius

    crassius Well-Known Member

    agree with both posts
  9. HeadSmess

    HeadSmess Well-Known Member

    was it running before hand?

    if so, why did you pull it apart?

    to clean it? why? does a bit of carbon on the piston really upset you that much?

    you reaped what youve sown... you stuffed your engine.

    if you had to post this question, save yourself the time and effort and just buy a new engine, and leave it alone this time.

    there is no reason to pull an engine apart unless it needs it. serves you right. ha ha and other vindictive comments :jester: po' lil engine :(

    my guess is you were completely unaware that the rings have little pins and notches that stop them rotating, and you just jammed the thing back in, possibly with a hammer.

    you know that rings "bed in" to the cylinder, and once you pop the cylinder off you have to re-hone the cylinder and replace the rings or it will always be a son of a pig forever after? possibly not.

    a pro engine builder wont even turn them over until its time to start them.

    what else? the circlips that hold the gudgeon pin in need the tags either removed or lined up in the direction the piston travels, or they snap off eventually.

    um, the piston has to go around a certain way or the rings tend to try to jump out the exhaust port, and then break. the lil pins are there to stop the rings doing this. as all two strokes do, other than the odd exception... 4 strokes dont need it, they dont have great gaping holes in the cylinder walls.

    once again, ha ha. congratulations :)

    im being nasty at the moment just so you get the point...dont fix what isnt broken!

    well, now you do have something to fix. giggity :jester:
  10. Fabian

    Fabian Well-Known Member


    The only time i look inside my engine is when it makes so much internal mechanical noise that my ears can no longer put up with all the rattling and clunking sounds, and these engines are able to make a heck of a lot of noise before they'll stop running.

    A bit of carbon on the piston (even a lot of carbon on the piston) makes no difference in the operation of the engine from my experience.
  11. HeadSmess

    HeadSmess Well-Known Member

    earplugs help :)
  12. butre

    butre Well-Known Member

    there's nothing wrong with being curious but maybe you should learn a few things about engines before you go tearing one down for no reason
  13. RollingStones

    RollingStones Member

    It was my first build and to be honest I wanted to be able to take it apart and get to know the inside of the engine in order to get to know it better.

    I actually ended up giving the bike to a body before moving from Austin to LA and he is ordering a new engine and getting it back in ridable condition.

    I have just bought a new beach cruiser and engine and am starting a new build today!!

    good times.