More bad luck: GXH50 Seized Up

Discussion in '4-Stroke Engines' started by Sketch, Jan 11, 2010.

  1. Sketch

    Sketch Member

    I got the new gearbox installed and everything was working fine...and then the piston seized up. Here's how it happened (already contacted bicycle-engines, waiting for a reply):

    After installing the new gearbox I did a short test ride and then checked the whole bike for loose nuts/bolts and inspected for any leaks - no problems anywhere. I also checked my oil level. It was, and is currently, filled to the max level.

    I did some longer rides - 2 rides that were each 12 miles long. Again inspected the bike.

    Then I started it and picked up the back wheel by holding the frame - and ran about 1/4 to 1/2 throttle, checking out the lack of perfect balance that my rear wheel (rim) has. I got it spinning at a moderate rate. It seemed like very reasonable rpm, certainly didn't seem like I was doing anywhere near an excessive rpm.

    After probably 30 seconds of doing that, the motor stopped fairly suddenly. Wasn't sure why. Tried pulling the pull start and it wound't budge. I took out the spark plug and gently set a screwdriver on top of the piston (which I found to be stopped at or near the top of it's travel) - then I tried pulling the pull start - the piston didn't budge.

    Up until then I was very impressed with how smooth and quiet the engine was. Could the oil distribution system have failed?

    I think I'm having bad luck, I know most people with this engine have not had this type of problem - so I wouldn't want to discourage anyone about this specific kit. I'm posting this in an attempt to get help understanding what the heck could have caused this. If I did something wrong I'm very confused about what that might be. Sure I'm a computer nerd, but before that I was a farm boy. I've been working on all kinds of small gas engines for over 30 years. Chainsaws, mowers, blowers, tillers, snowblower, generators, etc. I do RC airplanes. I've replaced the engine twice in a Honda civic. I not some city boy newb....

    (scratching head)

  2. Engine (might) be siezed

    Hi Friend, I too grew up on a farm (64,000 head of beef), and the last time I thought a motor bicycle engine had frozen, it was actually in the drive!

    Check your drive, heck, even do it for me?

  3. Sketch

    Sketch Member

    Doesn't look like my reply posted, so I hope it's not a repeat, but Mike can you please elaborate. What should I take a look at? I'm very open and even hopeful that it's not the seized cylinder/piston that I'm assuming it is.
  4. Sketch

    Sketch Member

    I've removed the gearbox cover, all is good there. I've removed the cover at the top of the engine to expose the lifters. There is strong evidence of oil having circulated there - oil in a pool around the lifters, and it's not even black, it still has the color close to what it is when it comes of the container.
  5. give me vtec

    give me vtec Active Member

    Im with mike...

    Try detaching the engine from the drive and start it up. This kinda thing happened to me on an eho35... the pull cord wouldn't come out. I though the motor had seized.... turns out the kill switch wire got caught in the cooling fan.
    Last edited: Jan 11, 2010
  6. ocscully

    ocscully Member

  7. arceeguy

    arceeguy Active Member

    Remember, Honda's don't seize - they become "difficult to turn".
  8. Old Bob

    Old Bob Member

    The "distribution system" is so simple on that engine its hard to imagine a problem.

    This isn't good, if its a seized piston you might as well buy a new engine.The GXH50 can not be bored over size, over size pistons and rings do not exist.If you could find a replacement block its going to be $$$$$$$$

    If its a seized rod you can get a crankshaft assembly.still expensive

    Take the gear box off the engine and take the starter off, to isolate the problem. check the clearance between the magneto on flywheel.
  9. Sketch

    Sketch Member

    I have no money to tinker with, I'm unemployed. I can't afford to buy engine parts. I can't afford a new kit. I'm trying to get work but for now that was going to be my ride... I knew I would have to work on it, and I looked forward to that. But I can't afford to rebuild an engine. That costs as much as a new engine...
  10. HoughMade

    HoughMade Guest

    Well if you you just got it...go back to the seller.
  11. Old Bob

    Old Bob Member

    If the kit seller doesn't warrenty the engine you are up the creek, Honda won't cover it.

    Did you pull it apart to determine what is stuck?
  12. HoughMade

    HoughMade Guest

    Contact them again, be polite. It's easy to ignore someone acting angry. I'm not implying you acted wrong or that you were being ignored by anyone...after all, I wasn't there, just a general suggestion whenever an issue arises...I can't help giving advice.

    Hopefully it is something simple. I have had my Honda engine for a couple of years and it has been a faithful friend. Good luck!
    Last edited by a moderator: Jan 19, 2010
  13. biketec

    biketec Member

    I'm only one man and contrary to popular belief I'm human. I was out do to illness all last week, So for people who left a message or e-mailed me I will do my best to get caught back up sorry for any inconvenience this may have caused, but again I'm sure we can work something out!
  14. Sketch

    Sketch Member

    I apologize for the 'outburst' in my posts. I'm working on the attempt to get warranty work done.
  15. Sketch

    Sketch Member

    Btw, I tried gently turning the crank and it turned easily but the piston did not move. It appears that something snapped inside...piston arm or whatever.
  16. HoughMade

    HoughMade Guest

    In a discussion about the HS engines elsewhere, someone mentioned the bolts holding the rod cap on being loose. Maybe something similar for you? Worth a look, but clearly if the crank turns, but not the piston, it's time to split the cases...if not you, someone else.
  17. biketec

    biketec Member

    Hummm makes a man wonder ..... The HS engine is known for loose bolts on the connecting rod and throw them, I wonder if Honda has begun hiring Chinese workers? Or ya never know it could be the wrist pin? who knows! Keys are always a good starting point? Try the warranty thing first see what they say and want from you and we will go from there.
  18. biketec

    biketec Member

    HAHA great minds think a like Hough!
    Do warranty, if that does not work as a quick fix in your own town you need to send it back and I will replace it and worry about the warranty myself. Besides I have always wanted to see the inside of one of them for a comparison but for the love of MBs please don't split it.
    Last edited: Jan 19, 2010
  19. HoughMade

    HoughMade Guest

    Good advice- leave the cases alone.
  20. Sketch

    Sketch Member

    Roger that, not splitting it.

    I have identified a honda place that has been very friendly and helpful with my father and some other people - recently talked a guy through fixing the timing belt for a log splitter honda engine without getting anything out of it himself. Going to approach him first with it (tomorrow). I just got the engine completely liberated from the bike and ready to take in.

    Thanks biketec for the support, I'll do my best here in town first.