I CANT GET MY CYINDER HEAD BACK ON/piston rings aren't flush!

Discussion in '2-Stroke Engines' started by Jace1, Feb 23, 2015.

  1. Jace1

    Jace1 New Member

    Oh my mercy! Someone, please help me. I've managed to screw everything up. I was taking off my cylinder head thing or the part that sits under it and it came off somewhat easy not much effort. Now I can't get the SOB BACK ON!!! Can someone please help me? I don't know what to do or how to do it. Clearly I'm a noob I tried squeezing the piston rings but it won't go back on. I'm currently staring at my bike thinking about how stupid I am. Every time I try to push it back on the rings stick out on side and the part that's around that holds the exhaust and carb, the piston rings push to one side and make it impossible to get back on. Did I break something? What did I do and how the hell do I fix it????

    Many thanks to all who are trying to help out this stupid noob. And it's the shaft I'm having trouble with I now learned. I noticed that I can turn the sprocket thing when I take the cover off along with the piston being exposed and the piston will move up and down by hand, but before this was not possible when I had the shaft on and the head attached, I couldn't turn crank with my hand at all, is there something wrong that I don't know about or is this normal? Please help. I don't understand what I did wrong and I want my bike to work... Thanks again for any help any of you can provide.
    Last edited: Feb 24, 2015

  2. Jace1

    Jace1 New Member

    Excuse the me, I don't know the name of all parts, clearly, it's the shaft that won't slide back on not the head.
  3. birdmannn101

    birdmannn101 Member

    Jace1, you need to make sure that the piston ring (where it splits) is over the piston pin if you want to get it back in to the cylinder. These pins are very small.

    Attached Files:

    Last edited: Feb 25, 2015
  4. KCvale

    KCvale Motorized Bicycle Vendor

    Nice pic.
    The pins are on the intake side (back) of the piston about an inch apart.
    The jug (aka the cylinder) has a bevel at the bottom to help squeeze the rings in, just kind of help it by squeezing the a ring at time in from the front once you are sure the groves in the rings are over the piston pins.


    If you don't have one borrow or buy one.
    This is the heart of the combustion chamber that contains the explosion of gas and air to make the head move down and turn the gears.
    If the head is not perfectly attached to the jug some of the explosions escape there making for a smaller boom and hence loss of power.

    The book calls for like 14 foot pounds, I run 66 engines at 20#.
    If it's a 48cc about 15# is all you can get.

    We get the flat and locking washers and nuts on hand tight.
    Then torque them all in a crossing pattern 5# at a time to 20# cold and ride it for a bit.
    Once it comes back and still warm we check them all again in a crossing pattern to get 20# on all 4 and call it done.

    Works well for us.
    Last edited: Feb 24, 2015
  5. jaguar

    jaguar Well-Known Member

    It's tricky getting the piston into the cylinder so I sometimes put it in while everythings apart and then put the cylinder in place over the cylinder studs but only half way and then put the piston pin in thru the piston hole and thru the upper connecting rod and its bearing. Then put the second circlip on while there is a rag under it to catch the circlip if trys to get away from you (needle nosed pliars)
  6. mrbg

    mrbg Member

    I'm thinking about going with a wrist pin & bushing instead of needle bearing for my worn out 66cc along with new piston and rings, better cdi from motopist, also thinking some nice looking rubber block motor mounts,but all that starts adding up. What do you think am I wasting my time and $$.on new piston & rings and the lighter wristpin & bushing?
  7. mrbg

    mrbg Member

    Just for the record I've had to replace basegasket on my other bike due to airleak which runs xlnt now with smaller mainjet a 62# I think. Anyhow good luck with your piston and rings, check out YouTube if your still not sure
  8. jaguar

    jaguar Well-Known Member

  9. mrbg

    mrbg Member

    thanks for the info I guess there's two types from bottom of skirt to top of piston pin ring 15/16ths and 11/8".I'm not going to mess around with the bushing it doesn't appear to have a good track record. thanks for the info