Cylinder Honing

Learn how to hone the cylinder of a lawn mower engine

Tools/Parts Required 

  • Cylinder Honing Tool, 100MM length, Must fit bore 61.5cm
  • Electric Drill

Step 1.

Disassemble mower down to an empty clean bore.

Step 2

Please note it is important that a cross hatch pattern is left after honing the bore this helps bed in the new rings, this can be achieved by moving the hone in and out as you go similar to that seen in the video. If honing for a new piston which is the same size as the old one, use some oil in the bore and only quickly hone a little bit at a time, this will make sure you do not wear to much away too quickly.

Step 3

If honing for an oversized piston do not use oil, until you are close to the required size of the new piston. At this point you may use some oil to slow the cutting speed and get an accurate finish.

Step 4

Be mindful that too little honing is much easier to fix then too much.


  1. Ok, from my experience with honing you don’t get a perfect even bore, don’t know why this is maybe something to do with the wine barrel shape these engines bore end up like, also because the front wares down more than the back end of the bore as the rings don’t come in contact to the cylinder walls.
    I used a 100mm stone like yours.
    In the end I had to place some electrical tape on the back half of the stones to get the 20+ oversize piston to slide in all the way, I think the best way is have it done at a machine shop, doing it with these honing tools will only follow the shape of the cylinder existing walls.
    Anyway I found using 10w-30 oil and some turps added keeps the stone from clogging up, I’ve yet to put the engine back together still waiting for a new second hand crank as mine was worn. Fingers are crossed that it all works, the piston skirt to wall is around .25 , the cylinder is closer in some spots stuffed if I know how when the stones are spinning in a circular motion well tension against the walls at a medium speed.
    Hope this will help others down the track. My advice if you want to do it is tape the stones as I have first and get the back down close to the front diameter first and finish off the lot without the tape to correct diameter or you will end up as I did with a cone instead of a cylinder. If you have a better way then please advise!!
    200 for a do it yourself re-build I wounder if you can still buy a small block for these and save the hassles of wasting money on do it yourself hacks and hoping it will run another 5 years.

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