Play in Piston / Connecting Rod. Some ticking

Discussion in '2-Stroke Engines' started by willie634, Aug 12, 2015.

  1. willie634

    willie634 New Member

    So what if the piston bearing has up and down play on connecting rod??

    I get I ticking noise from top end when engine is hot. Only at certain throttle levels too. Engine vibration is mild, I don't tun it hard.

    I've inspected top end and even gave head gasket a bigger opening. Some residue was chipped off, could I have done permanent damage?

    I've tried a new bearing too, but they sit very loose in connecting rod :$
    Last edited: Aug 12, 2015

  2. willie634

    willie634 New Member

    ticking starts when the engine gets hot.

    I have a new engine, but this one came with a thicker gasket. I did put a thinner regular one in and perhaps that could have started the sound. Kinda sounds like a jackhammer but not intense.

    I have been adding more gasket under head. I will have to try more...

    I am really just wondering if vertical play is normal at the connecting rod / piston bearing?. If the damage was permanent it would make the sound while cold too right?
  3. crassius

    crassius Well-Known Member

    if your piston has been hitting head, then play happens as the piston or rod gets hammered

    not too often that this happens tho
  4. willie634

    willie634 New Member

    Thanks crassius

    Somewhat got some success yesterday.

    I put in 3 bottom gaskets!!

    Wow most low end power I have ever had!! Low vibration and little loss of top end. Worth its own thread!!

    The ticking went very quiet too which was amazing. After 30 and engine very hot ticking came back almost as loud as before.

    Might add another bottom gasket and round edges of piston slightly. But will try in cold again today
  5. crassius

    crassius Well-Known Member

    unless you've changed the cylinder or piston from what came with the engine, it seems strange for it to be hitting the head - if all is standard, then I'd guess a bad bearing is making the piston fly up loosely

    you may have serious problems coming in near future if it isn't sorted out soon
  6. willie634

    willie634 New Member


    Great success today. Now that I figured out the issue I pulled new engine out of box. Guess what.. no vertical in piston bearing.

    My engine came with a thicker gasket than normal, when I had put regular gasket in it, I guess it caused damage.

    I installed new engine with 4x BOTTOM GASKETS. Gaskets are just under .030 and when compressed just over .020.

    Not taking any chances on this one so made bottom gasket extra thick then used regular head gasket. 3rd engine already. What an ordeal to figure out. But so happy now

  7. willie634

    willie634 New Member

    It didn't take very long for new engine to start ticking.

    Now only a few weeks and as soon as engine warms ups it has ticking noise, mostly at slightly faster speeds

    I live in a hilly area at it gets quite hot I'm sure. I wonder if it's just a crapy model of engine..
  8. crassius

    crassius Well-Known Member

    lost track over last few weeks - this is motor you modified when you got it?

    noise can often be due to leaking head gasket, you might want to check torque
  9. willie634

    willie634 New Member

    Two new motors from one supplier. Both developed and ticking and eventually knocking noise. Like an intermittent jackhammer sound. No knocking when cold.

    I check head torque daily in beginning. I'm sure sound is coming from wrist pin area.

    Also I have switched to ethanol free and would like to not let ethanol touch new engine. Ethanol free doesn't seem to make ash buildup and even cleaned out ash from ethanol.r

    The connection rod says "Z-L" or "7-Z"
  10. crassius

    crassius Well-Known Member

    rod bearings usually are good or bad - if no play is felt, then they are usually good

    is this an engine you modified?
  11. jaguar

    jaguar Well-Known Member

    if there is free play at the upper rod bearing then you need to change that bearing out immediately.
    you can use solder on top of the piston, turn the engine over slowly, then see if the solder was squashed. measure what its minimum squashed thickness is. It should not be less than .3mm, and if so then you need more gaskets.
  12. willie634

    willie634 New Member

    This problem has arised with two new engines.
    (The engines not not modified, except for me trueing the head section. I putt a thicker bottom gasket to accommodate the thicker head gasket it came with.)

    Connecting rod labelled "Z-L"

    This video shows the different models of engines by connecting rod!!:-/:cool:

    Last edited by a moderator: Dec 15, 2015
  13. jaguar

    jaguar Well-Known Member

    you should be able to see at the top of the piston if it is hitting the head or a gasket that extend inward
  14. willie634

    willie634 New Member

    I put an extra thick bottom gasket on last new engine to be sure it didn't touch.

    Ohh... and changing to a new wrist pin bearing did nothing. Even tried new wrist pin on last engine and that didnt help either.

    The only way it could have touched the gasket was by ash buildup on piston head. Checked piston a few times and no signs of contact.

    The ethanol free seems to avoid ash buildup. So next engine will be ethanol free from the beginning.
  15. jaguar

    jaguar Well-Known Member

    but you said there was free play at that wrist pin bearing (which can only be fixed by replacing the bearing unless the rod or wrist pin is worn down which is unlikely)
  16. willie634

    willie634 New Member

    There was free play in first engine after using. Then I got new engine. New engine had no play, but developed play again, even with extra thick bottom gasket

    The wrist pin bearings that came with these engines were different than normal ones I have seen. All the pins were tight and not free floating like other bearings
  17. crassius

    crassius Well-Known Member

    I'd be curious what would happen if the motors were to be run right out of the box with no mods to heads or gaskets.
  18. willie634

    willie634 New Member

    I went back to original head bolt setup. Hand tight and back a quarter turn, and no double bolt needed. After more testing i did notice that they dont move around.

    Have been running motor for months with no problems. Ticking noise is still there but doesn;t seem to be big issue.

    What i have learned now is that on a new engine i would not mod head unless there is a head leak. Just leave it alone! Its nice to sand the head and make a new seal, but just taking it apart and messing with it can make things not run as smooth.