Broke a piston ring on my first build

Discussion in '2-Stroke Engines' started by Miriax, May 7, 2011.

  1. Miriax

    Miriax New Member

    I broke a piston ring because I was foolish enough to take the piston cover off of my shiny new motor. I still have the lower ring perfectly fine, but the upper piston ring broke into four pieces. I've managed to super-glue it back into two pieces.
    Can I use it glued back together like that, or would that hurt more than help?
    What kinds of ill effects would occur if I ran with one ring or with the broken ring? Nevermind, I found my own answer by searching a little harder.
    I only see 60cc replacement piston rings for sale on my vendor's site. Can I easily find the right rings elsewhere, hopefully at a local mechanic store?
    I don't know what dimensions are different for 48/60cc engines. If I ordered a replacement set of rings intended for a 60cc piston, would they work with my 48cc, or is the diameter of a 60cc piston larger?I also found the answer to this. Stupid question really.
    Do I need any kind of special tools to replace the ring? After searching I've read a little bit about ring spreaders. Are they necessary?
    Thanks for the help guys. I haven't even been able to mount my motor (need to drill the frame tomorrow) and I've already broken it. :(

    ~Miriax

    Edited to reflect answers I've found for myself. Still looking for more help though! Thanks!
     
    Last edited: May 7, 2011

  2. adrian101

    adrian101 Member

    Hey Miriax. i would not place the super-glued piston ring on. It will basically come apart again as the heat from the piston will make the glue soft again, which will in return end up falling apart and damaging the walls/piston sleeve.

    If you have a 66cc motor then you can only place the 66cc piston rings on as the diameter is larger then the 49cc engine. visverser with the 49cc, the 66cc rings would be larger in diameter. you can get piston rings from many motorized bike vendors or eBay

    With placing the rings i suggest ring spreaders. me personally have used two pair of pliers but ring spreader are the way to go if you can get your hands on them.

    Hope that helps, and again super glued piston rings and a very bad idea to place into the engine.

    Enjoy your riding once your bike is on the road.

    Good luck!
     
  3. hardly_rolling

    hardly_rolling New Member

    The best thing to do is order new piston rings and you really dont need any special tools to do it. I did the same thing only i blew up my rings and piston. Luckily my cylinder walls not damaged. A quick reminder do not put octane booster in your gas, your pistons don't like it. :0
     
  4. Miriax

    Miriax New Member

    Thanks guys, you're awesome!
    The main thing I need to know now, is whether anywhere carries the rings in-store. Maybe a motorcycle shop or an automotive repair place?
    Cuz if I have to wait for a new set of rings to arrive, I'm going to be a sad bikemonkey, but if I can go pick them up somewhere (anywhere), I'll go do that.
    Thanks again!
    ~Miriax
     
  5. GearNut

    GearNut Active Member

    You are pretty much stuck with ordering them from a vendor.
    I am not saying do not try to order them from a motorcycle shop or automotive shop, but I wish you the best of luck finding a parts clerk who will actually take the time to measure your one good ring and match it up perfectly with a ring set that fits some other engine. More often than not all the parts person has for resources is an exploded view of engines and engine accessories showing replacement part numbers. The exploded views rarely show the part dimensions.
     
  6. Miriax

    Miriax New Member

    I got it all put together. :)
    I figure I won't waste another topic asking this, but...
    Should the bike be REALLY hard to roll without depressing the clutch lever? It'll roll without it, but it's like pushing it with the brakes engaged partway. It also makes a THUP THUP sound from the piston housing when I push it without the clutch depressed. Do I have the clutch cable too tight or too loose or something? It'll roll a lot smoother with the clutch depressed, but there's still noticable drag.
    I've tried taking the spark plug out, and playing with the tension roller, and there isn't any difference. What am I doing wrong?
    ~Miriax
     
  7. adrian101

    adrian101 Member


    Yeah the bicycle should be hard to move if the clutch lever is in the out position(not being pressing inwards). When peddling or moving your bicycle make sure to pull the clutch lever inwards so you can move the bike freely. If not you could damage your piston and cylinder walls.

    To start your bike, hold the clutch in while going down a hill or peddle then release the clutch so it engages and starts your bike...

    if there is alot of drag when the clutch is being held inwards, you need to loosing it off a little. but there should be drag once you release the clutch. If not your engine will not start.

    The "thup thup" noise is your piston going up and down in the cylinder.

    Hope that helps. good luck
     
    Last edited: May 8, 2011
  8. motorpsycho

    motorpsycho Active Member

  9. Lazieboy

    Lazieboy Member

    Ring issues

    My rings broke after riding one day. The Crank locked up due to Pieces of broken ring. Nice gouge in Cylinder wall and piston head looks like the moon.
    Tore motor apart,cracked case. metal slivers and grime inside. One ring is ok top one broke. Instead of spending $110 in parts thinking 200ish for:
    http://www.kingsmotorbikes.com/grub...lant_head_black_finish_bicycle_engine_kit.htm
    Also found this that helped me.http://www.motoredbikes.com/album.php?albumid=808
     
  10. motorpsycho

    motorpsycho Active Member

    ummm, you did add oil to the gas right?
     
  11. Miriax

    Miriax New Member

    I'm running!
    I spent all yesterday afternoon troubleshooting the motor.
    I had the idle speed way too low, the choke adjusted wrong, the kill switch hooked in wrong (I think) and the biggest problem was that the throttle was on upside-down!
    I also discovered that instead of holding the clutch lever down manually, there's a barrel on the grip that I can depress that will hold the clutch down. SO much less work.
    Now she runs, and all I need to do is fine-tune her. I'll have to take some pictures and return tonight!
    Thanks all!
    ~Miriax
     
  12. Lazieboy

    Lazieboy Member

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