how to compress piston rings?


Old 06-06-07, 02:10 PM
Thread Starter
Join Date: Feb 2005
Location: Michigan
Posts: 335
how to compress piston rings?

Sorry if this has been posted before, I did not see it on a search.

Im putting a small 25cc 2-stroke engine together, and I cant get the cylinder over the piston rings, I have just been squeezing them by hand, and trying to fit the cylinder over them, but i can never get it on right, I think im getting it but then look at the other side and see the ring sticking out on the other side. there are 2 little pins on the piston groves to keep the rings from turning. (ring gap must have pin in it) I havnt seen a ring compressor that handles anything so small in any local stores, and I dont want to force anything, or cause any knicks in the rings.

I know some of you have done this hundreds of times, what are your tricks.

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Old 06-06-07, 02:51 PM
Join Date: Aug 2005
Posts: 2,268
Just a shot in the dark - have you tried to make your own ring compressor using a proper sized hose clamp? Adjust it snug over the rings/set over the cylinder and tap in with your mallet.... As I said... just a shot in the dark.... something I would try in your shoes....
Old 06-06-07, 06:48 PM
puey61's Avatar
Join Date: Apr 2004
Location: Upstate New York
Posts: 3,224
The idea thezster suggested won't work since on a two stroke the cylinder is dropped onto the piston, not vice-versa. What works is patience and a tiny screwdriver and work your way around carefully and making sure the ring(s) are setting properly on the locating pins. The cylinder should be tapered at the bottom to aid you in sliding the cylinder down over the rings. Good luck.
Old 06-07-07, 06:08 AM
Join Date: Nov 2005
Location: North Carolina
Posts: 948
i have a set of plastic ring compressors that work well. don't remember where i got them. probably Sunbelt or Rotary.

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