How to Install Piston Rings on a Four Stroke Piston.

Hello. My name is Mantvydas Miklosius. I am currently studying mechanical engineering in Technological University of Shannon in Athlone. In this instruction, you will find how to correctly remove and install piston rings on a four stroke piston.

For this task you will need:

-Piston ring pliers.

-A new set of rings (IF applicable.)

A piston ring pliers is not a requirement although it is recommened to prevent breaking piston rings with your hands. In this document I will only be using piston ring pliers.

In front of you, will be a piston with the piston rings installed. In the picture above, you can see a total of five rings inside the piston grooves.

(First two grooves.)

First ring from the top: Compression Ring one.

Second ring from the top: Compression Ring two.

(Last groove.)

Top ring: Oil control ring.

Middle ring: Oil expander ring. (spring like shape)

Bottom ring: Oil control ring.

The pliers are used expand the rings to allow the rings to clear the piston and be seated comfortably in the grooves.

Note: The pliers will only be used for the two compression rings as the oils rings are to small to be removed with the pliers.

In the picture above is the correct side up of the pliers. At the top of the pliers is where the piston ring gaps will be seated in to allow the pliers to expand the rings.

CAUTION! Do NOT expand the rings much more than the diameter of the piston. If expanded too much, the ring will snap and or create perminent damage that will reduce performance of your engine.

• Place the gap of the top compression inside the front of the pliers.
• You may need to push out the ring gap out from the groove to give the pliers space to grip the ring.
• Squeeze the pliers until the ring expands enough to clear the piston. Lift the ring up from the top of the piston and place it on a surface beside you.

This step is similar to step 3. The only difference is that the second compression ring is in the second groove in the piston. Take extra caution taking the ring out to avoid the ring slipping out of the pliers and entering the top groove.

You now have a piston that has both compression rings removed.

In the picture presented above, there is a total of three rings inside groove three. These are the oil rings.

The top and bottom rings are much more skinnier and flexible than the compression rings. Because they are skinny the pliers will not catch the gaps. Removing them you will need to use your fingers.

The middle ring is the oil expander ring. It is a spring like ring and is the easiest ring to install/remove.

Removing the oil rings is the most difficult task endured in the process.

• Indentify the top ring of the three pairing. Find the gap of the oil control ring.
• Catch the gap of the ring with your index finger nail and slowly begin expanding the ring.
• Lift the one part of the gap up and place it on top of the piston like in the picture provided.
• Then, roll out the ring from the gap until the ring is free from the groove.

Repeat the same process with the bottom oil control ring.

Upon removing the oil control rings there will be a oil expander ring left to remove. This ring is reasonably flexible and is easy to remove.

• Locate the split in the expander ring. In the picture above is how the ring shall look inside of the piston groove three.
• Catch your index finger nail in the split or beside it and expand it. You will find that the ring expands easily.
• Roll the ring out just like the oil control rings.

Upon removing the rings, you will have a naked piston infront of you. Installing rings is the same as removing only adding in a few extra details to ensure that your engine will run as intended.

Make sure you prepare the piston for new rings by cleaning out the gaps with compressed air or blowing out the gaps with your mouth.

Always check the piston ring manufacturer's manual as there may be some extra details not covered here.

Installing the expander ring is basically the same as removing.

Note: There is no top or bottom of a oil expander ring

• Begin by locating the third groove from the top down.
• Then, expand the oil expander ring.
• Place the end of the gap inside the groove and roll the ring in the same way as you removed it.

CAUTION! Make sure that the split between the ring is NOT overlapping eachother. They should only be touching. (Revert to the picture above)

When installing both ring oil control rings, be patient and take your time it is important to get this step correct.

Note: some oil control rings don't have a top or bottom, if unsure consult with the manufacturer.

• Begin by orientating the oil expander ring in your hand like in picture one.
• Just like the oil expander ring, place the end of the oil control ring BELOW the expander ring.
• Then, roll the ring around the piston until it seats perfectly underneath the oil expander ring.
• Repeat the same process for the top oil control ring.
• The top oil control ring should sit on top of the expander ring.

CAUTION! Ensure that the ring gaps are facing eachother and equally under the oil expander gap.

Note: Some compression rings have angled edges or letters stamped on. These details mean that there is a certain way the rings are meant to be seated inside of the two grooves. Because this instruction is general, and the fact that both compression rings used in instruction are identical, I will not cover what these mean as every manufacturer may be different. Please consult with a manufacturer or do further research before installing.

• Begin by taking one of two piston rings and inserting them into the pliers like in picture one.
• Expand the ring until it clears the pistons diameter.
• Begin by putting the second from the top ring in first.
• Release the tension of the ring when you are in the correct location of the ring (groove two)
• Repeat the same step with the top ring.

Orientating the rings correctly is important as improper orientated rings will reduce performance or create engine failure.

The diagram provided above is the correct way to orientate the rings.

• Begin by orientating where the front of the engine is. This information can be found by looking at the top of your piston. As you can see, in the picture above the piston has "IN" writting on it. This stands for intake which is at the front of the engine. Other pistons may have a arrow pointing to the front of the engine, other pistons may not have a front or back.
• Use a pick if needed to move the oil rings in the correct manner. The compression rings can be easily moved by your fingers.

That is the correct way to remove/install piston rings on your engine.