Engine Trouble engine seized (piston locked to head)

Discussion in '2-Stroke Engines' started by mastacalus, Apr 2, 2013.

  1. mastacalus

    mastacalus New Member

    Hello I am fairly new to 2 stroke engines, but this is my second motor. The first 1 ran for about a month until I had it screaming at 52 miles per hour and melted the piston to the side of the head... So I bought a new one. I just got it installed last night and took it for about 4 small runs. It ran great...

    This morning I got up to go to work and I went to start it it made about 3 revolutions and then the back tire seized up.

    It felt exactly like when the piston seized to the head and melted itself in... considering that the bike had not even started yet I knew this was impossible. So I took the spark plug out and pulled the top of the head off Then went to remove the head and the piston moves with it. Try to softly tap on it with a rubber mallet, no go. I know I'm going to be able to get the piston off of the side of the head but I'm wondering what I am doing wrong? And what might be the ea.siest way to actually get the piston off of the head without causing any damage? I bought the motor from livefastmotors.com, not sure if anyone has had an issue like this

  2. BigBlue

    BigBlue Active Member

    52 mph, your going to burn your engine up every time, especially if your going downhill - not enough lubrication.

    What is your oil/fuel mixture and type of oil? Make sure the mixture is well mixed.

    Good Luck,

    AKA: BigBlue
  3. mastacalus

    mastacalus New Member

    The 52 mph was more of a 1 time thing than anything else, I just wanted to see what it was capable of. Now this is a new motor that I bought and installed, no problems, but this motor hasn't even gone above 20 mph yet.

    Now, onto answering your question. I'm using what I was told for breakin, which is 32:1, maybe I have it backwards? But either way, I'm wondering if it even had enough time to do any real damage. The type of oil Im using is a very cheap brand I think - "Itasca 2-Cycle Engine Oil."

    Consider this, and tell me if I'm off a bit - The engine ran very nice 4x, sounded great, the whole shabang. This morning it was a bit cool, so I guess since the piston could've been cold just a hair smaller to where the piston could've cocked a little to the side and just enough room to catch on the piston ring or something? Does this happen often? If it does is there a way to try and prevent it from happening again? Thank you for help in this matter.
  4. grinningremlin

    grinningremlin Active Member

    If you have $$ for spare engines you're good, otherwise look at it like a car, just because it can doesn't mean you should.Personally from all I've read here I don't think china-girls are for beating, unless they're seriously modded and well maintained, they're fraught with slop.Go with a quality jap motor set up, costs more to begin with, but you won't be on your second engine any time soon.
  5. swamprat

    swamprat New Member

    what did you do to get 52 out of it. they don't normaly go that fast. when you say the piston is stuck to the head are you sure that you don't mean cylinder. the piston is not supposed to touch the head?
    if you take the head off you will see the top of the piston in the cylinder.
  6. mastacalus

    mastacalus New Member

    If you re-read my thread, the new motor is the one with the piston jammed, I started it up after install, ran it gently around the block 4 times, and pit it up for the night, woke up to ride it, and upong releasing the clutch to start it, the piston jammed in the cylinder. The motor that did high speeds is toast and not on the bike.I just want to know if anyone else has had these problems and of so, how did you fix it?
  7. crassius

    crassius Well-Known Member

    from your post, it sounds like the piston is stuck in the barrel rather than the head - if this is the case, then remove the studs (by double nutting) so you can twist it a bit to free a broken ring from the ports
  8. relaxxx

    relaxxx Member

    If it was mine I'd probably try to budge the piston with the spark plug removed. Spray lots of lubricant inside, let it soak, heat gun or torch the head/cylinder to 350F or so, find a steep hill and try to turn it...
  9. mastacalus

    mastacalus New Member

    I thought about removing the head studs as well. That's what I think I'm going to try first, I just thought I'd ask to see if there was anyone who had this same issue and achieved their desired result. Thanks everyone, more replies are welcome of course.
  10. V 35

    V 35 Member

    The 3 revolutions bothers me, if the fuel was left on, the carb overfloated, the cylinder hydro locked, than it wouldn't budge, right ?
    Since it spun a few times, I'd check the clutch / small bevel gear . I could of sworn my Skyhawk seized, but it was just a broken, and jammed bevel gear. Good luck. As for 2 stroke lube, the golden rule is ... Add Extra Oil for Break in. I like to short the gas, if it calls for a gallon, I put in 3 quarts, resulting in an oil rich mix.
  11. Mowen McGuire

    Mowen McGuire New Member

    Use a higher flash point synthetic oil, 20w50. (valvoline?) At 40:1, don't dive over 20mph for the first 2 tanks. To get the piston out, might have to split the case and use a 2x2 and a 2lb sledge.
  12. Fabian

    Fabian Well-Known Member

    52 miles per hour is only achievable if pointing the bike down a steep hill with the throttle held wide open.

    Once these engines are revved over 5,000 rpm, their life is considerably reduced, especially if using the standard CDI.
  13. mastacalus

    mastacalus New Member

    Update for the Seized motor.

    So, yesterday after work I took a block of wood small enough to fit in the cylinder and went to town. After the piston was out, I noticed some etches at the bottom of the cylinder where it looks like the piston ring ends popped out and jammed themselves into the sides. What would cause this? Is it just dumb luck? No real damage to the piston at all, looks brand new because it's a brand new motor, and I don't see how this would effect compression. Anyways, the motor is running strong and I want to know more about these motors, how can I make a good "break in" mixture? What's the best oil to use? Can I use regular oil from the auto parts store? Is synthetic good? Please let me know so I can take it into consideration.
  14. crassius

    crassius Well-Known Member

    more likely there were some loose metal pieces left in the motor by the factory
  15. crassius

    crassius Well-Known Member

    more likely there were some loose metal pieces left in the motor by the factory, or maybe your main bearing has lost pieces
  16. sixbysix76

    sixbysix76 New Member

    dude im on today for that very reason!! My clutch bay was full of fuel! i get that if i leave the fuel on gravity pulls the fuel but its went threw the jug into the crank and out the torque converter/ clutch gear assembly!! k i get dont leave fuel on. but now what about the grease for the clutch or crank? it feels washed out. without going into learning howto pull it apart, can you or someone tell me if im just trippin? cant afford burnt out or seized moter!
  17. Skyliner70cc

    Skyliner70cc Active Member

    Gas isn't for everyone. Electric or pedal power should be considered....I be trippin
  18. HeadSmess

    HeadSmess Well-Known Member

    clutch full of fuel...what about the magneto side?

    you have hydrolocked it? carb floods, fuel down the intake port, fills case. a brutal turn over forces everything that wont compress (fuel) out through the weakest point. usually the crankseal under the magneto. the clutch side is twice as thick... i dont see it fail too often.

    BUT fuel can also sneak in there from simple carb leaks...theres a nice little "catcher" just above the jackshaft bearings... a bad gasket will let it in! so, it doesnt HAVE TO BE the seals.

    running with a defective seal will let it rev out nice. leans it out a bit, depending how bad the seal is. too lean and things start melting... could also be a gasket blown.missing, incorrectly installed.

    you didnt mention engine SIZE. i reckon you got a 66. POS!

    i still think 52 MPH is BS. thats nearly 100km/h. they go that fast in the courier van. not in a bike. not in stock trim, with stock pipes and stuff.

    oil ratio? i still run 50:1, even on this so called "break in" period. only motor to ever sieze on me was the 66. junk from the minute it arrived. just tried rebuilding it today. so, the new piston is 5mm lower in the bore? great. POS! its getting melted next week!
  19. Fabian

    Fabian Well-Known Member

    Can't say that i've had any serious problems with the 66/69cc engines. With the Jaguar CDI and 25:1 oil/fuel ratio, they happily chug along if keeping rpm below 5,000.

    52 mph is completely unachievable using a standard 66/69cc engine, unless the bike is gravity assisted, and if that's the case, then the engine will have revved in excess of 8,000 rpm, which is terminal for engine life.
  20. joshua97

    joshua97 Member

    undo the full four studs then try twisting barrel to free it. u probe broke a ring,, the live fast kit are horrible (no offense meant) try a zbox or scremingroo kit but sounds like a rings snapped or the gudgeon clips broke off and gudgeon pin slipped out