piston froze!

Discussion in 'Motorized Bicycle General Discussion' started by ex-28, Jul 23, 2010.

  1. ex-28

    ex-28 New Member

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    welp was out riding today for aboout 25-30 min , stoped for a break then hoped back on all was fine went another 5 min and stoped again for 10 min , then off i went again and lost all power engine slowlly came to a hault , tried everthing to get it to turn over but no go , got home pulled the plug only to see it was verry white in color, i was liek great she's siezed , so i poped off the head taped the piston down with a cloth on top and a mallet and finally she gave way , it was in the up most position when it was stuck. top of the head is all ok , no marks at all , everthyign is fine except for the gouge on the side of my wall as seen in picture. i have over 500 km on this and it turning a month old in 2 days , its the 80cc black slant engine kit from zoom
    i did the proper breakin and been running 32:1 mixture for the last 3-4 tanks i always check my plug to keep an eye on it and it's always been perfect golden brown.

    i'm not sure if i threw a ring or not yet but after i freed up the piston i took it out pedeled up to about 25 and poped the clutch she started to go a bit but i cant keep it running theres no compression ,


    a gouge like that makes that much of a difference ? , i notice there is some tiny shvings in my pic so i thinking i threw a ring and it choped it into fine shavings but i have to pop the head all the way off to check for sure. as the head piee is fine.


    i'm not sure what to do from here zoom has the 80cc engine replacements on for $70 i have a $10 off copon but its the old Yong Xing engines not the flying horse one that i have and i dont think its a slant engine.

    if i were to fix this myself rather then buy a new engine itself , the head i think is 15 bux , not sure if i need a piston and the righs yet as i have to pull it all apart just wondering what some opionions are with this.

    thinking it woudl be cheaper to jsut buy the parts , but not + on all the parts i would need to fix this but the top of piston head looks fine it's just the side wall thats a mess. :(
     

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    #1 ex-28, Jul 23, 2010
    Last edited: Jul 24, 2010
  2. skuzzy

    skuzzy New Member

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    Definitely stuffed barrel by the looks of it will destroy compression, replace the barrel, unless you want a new engine under warranty? if it is valid?
     
  3. ex-28

    ex-28 New Member

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    prob not under warrenty , but not sure got from zoom bicycles i'm 2 days short of a month , but i dont belive they ahve any sort of warrenty after its up and running.

    took the piston off and i got a good look at it now , the small clip that holds the piston down to the shaft looks like that broke off and made its way up the side to the rings then it took out both my rings , there on there still but are broken up pretty good.
     
  4. Kevlarr

    Kevlarr New Member

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  5. ex-28

    ex-28 New Member

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    nice but i have to see how much shippin is to canda :(

    arug zoom is outta stock on the 80c piston. sigh...

    is there a walkthrough , on how to clean and flush this baby out now ? , i really dont want to ahve to split the engine bottom end apart , i have the whole top end open now and carb ,muffler off , will unmount off bike next but jsut wondering how to clean out all the small tiny shavings from the bottom end now.
     
  6. mapbike

    mapbike Active Member

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    I just got the lower end of a 66cc Slant Head I'm rebuilding together today, I had a very simular issue like you did with your engine and I can tell you from my own experience that the only way to be sure that you get it cleaned properly is to open it up, I know you dont want to do that and you might get away with just blasting the inside out real good with carb. or brake cleaner and then using highly compressed air to blow the heck out of the crankcase. but then again you may not get away with it and guess what...? you are right back in the same trashed engine situation again and you would have been better off just getting a new engine to start with. It's your call on it but if it were me I would just take the time to do it right the first time or if I didnt have the time I would just buy another engine and fix that one later when I had the time.

    Good luck with what ever you do, I hope it works out good for ya and gets you back on the road asap.... God Bless, Shan
     
  7. ex-28

    ex-28 New Member

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    ya totally understand what your saying , i gotta go find a thread showing how to crack the engine apart, it was taking off the clutch big nut in there i was tryin to avoid doing , i have a friend that works in a sall engine repair sop , thinking he might be able o flush the motor out for me with his machine. , not i just have to find replacment stock for top end parts , prefer in canada , zoom has everthing except the piston itself in stock
     
  8. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    The best way to clean out the bottom end is to flush thoroughly with warm, soapy (dishwashing liquid) water, followed by drying it with compressed air, and finally, a shot of WD-40 to remove any traces of water.

    There are not any real "nooks and crannies" for the crap to hid in, and this procedure should be more than sufficient.
     
  9. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Also, find out why it went lean before you run it again.
     
  10. ex-28

    ex-28 New Member

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    my theory is i'm thinking it didn't go lean , the plug changed white after i lost compression i remember riding it for a min or 2 after i started it last and it just got slower ad slower and slower then died. but then again this is the 1st little engine i ever worked on like this , 15 yrs ago i used to rebuild car engines ect but this is all new to me.

    maybe the plug wasnt as white as i thought but it is alot lighter then it usually was.
    as for the metal head gasket it looks in good shape but not sure it if forms the shape when its used as it does have a verry slight flange in the middle of it . so not sure if it needs replacing to or not. head and middle gasket and in great shape.

    my only question is turning the left most set screw (closted to air filter) to let in more air , does that mess with the engine getting less oil ? . this bike's top end running at a steady 50 km/h wot , but i never ran in wot verry much as didint want to chance anything on these little engines but if i ever needed to it would do it.
    the day this happened i was only going about 25 through some trails
     

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  11. DudeZXT

    DudeZXT New Member

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  12. ex-28

    ex-28 New Member

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    i called and exsplained what happened they were happy to cover it under warrenty , parts are on the way to me now ! , long live zoombicycles , thank you soo much !
     
  13. severedcorps

    severedcorps New Member

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    i love zoombicycles

    their warehouse is a 5 min ride away from me :)
     
  14. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Nice...a happy start to a happy ending! Just keep every thing clean and don't forget to use LocTite to keep it from coming apart. Make sure the g-clips seat properly in the piston, you don't want the same thing to happen all over again....cheers!
     
  15. ex-28

    ex-28 New Member

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    indeed i will keep an eye on it , i picked up an engine day after this happened to me so now least i'll have a spare , i cant be without my bike :)
     
  16. DudeZXT

    DudeZXT New Member

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    Yay, Zoom! My first build I broke the plastic in the throttle tube because it didn't seem that the throttle had been returning correctly and I pushed it forward, forcing the throttle cable to tear through the plastic cable retainer.

    They also sent me only one engine when I had ordered 2, after the first incident, and made up for the shipping error with a nice freebie.

    Only company I will deal with for future engine purchases and recommend them to everyone who asks about where I got the kit.
     

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