1997-2001 Honda CR250 – Top End Service – Part 11: Piston Installation

How To Install The Piston On Your 1997 – 2001 Honda CR250.

1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston InstallationThe Tools You Will Need Are:

  • Feeler Gauges (Amazon)
  • Small Pick
  • 2-Stroke Oil
  • Assembly Lube

The Parts You Will Need Are:

  • New Piston Rings
  • New Piston Pin Clips

If you are installing a new piston, I suggest a Pro X piston kit. It’s a cast piston, so it’s a little heavier than forged, but it costs much less. Pro X is distributed and supported by Wiseco, so if you have any questions, you can just call.

Related: The 3 Types Of 2-Stroke Oil For Dirt Bikes To Match Your Budget & Performance Needs

I already put together an article covering piston selection, so I’m not going to go into that here, but a cast piston works for me because I will be installing it in a bike I use for enduro.

But just in case you’re curious, here are your options over at RockyMountainATVMC.com.

  • OEM – $75
  • Pro X (Cast) – $85
  • Wiseco (Forged) – $122
  • Vertex (Cast) – $138

Click Here To Open The Top End Specifications Table In A New Window

Gap New Piston Rings

(Click To Start Slide Show)
Before we install the piston rings, we need to make sure the end gap is within spec.1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Ring In Bottom Of Piston
Place each ring into the bottom of the cylinder, and push it down with the piston.1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Push Piston Into Bottom Of Cylinder
Measuring the ring gap with a feeler gauge.

The end gap on both rings should be no greater than 0.13 inches.

1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Measure Ring Gap With Feeler Guage
 

If the rings are too tight, you can file the ends with a fine metal file until they are in spec.

1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Meassure The Gap Like This

Piston Pin Clip

Install the first piston pin clip into the pin bore groove.

Your thumbs and a small pick should work just fine, but be careful not to gouge the cylinder with the end of the clip.

1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - First Pin Clip
Rotate the clip, so the opening faces up.1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Rotate Clip So Opening Faces Up
Piston Ring Installation
Double check that the rings are clean and dry.

Lubricate the piston edge and ring grooves with 2-stroke oil.

1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Lubricate Piston Crown And Groovs
Check that the IT mark is facing up, and align the bottom ring with the alignment pin.

Spread the ring just enough to clear the piston, and install straight down, do not try to wrap the ring into the groove.

Check that the ring is free in the groove.

Repeat for the top ring.

1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Install Rings
We are using oil to install the rings, but the oil needs to be thoroughly wiped off afterward.Be Careful!
Piston Installation
Lubricate the pin and pin bore, and press the pin into open side of the piston.1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Lubricate Pin Bore 1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Press Pin Into Bore 1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Push Pin This Far
Apply assembly lube to the connecting rod opening, and install the needle bearing, then apply lube to the inside of the needle bearing.1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Lubricate Connecting Rod Bore 1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Install Needle Bearing1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Lubricate Needle Bearing
Position the piston over the connecting rod, so the IN marking is facing the rear of your bike.1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Position Piston Over Connecting Rod
Press the pin through the connecting rod, and seat it against the pin clip on the other side of the piston.1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Press pin into connecting rod bore
Install the second pin clip with the opening facing up.1997 - 2001 Honda CR250 - Top End Service - Part 11 - Piston Installation - Install Second Pin Clip
Before you move on, place your piston holder to keep it in place.Be Careful!
Part 10: Exhaust Valve InstallationPart 12: Cylinder Installation
1997 - 2001 Honda CR250 - Top End Service - Part 10 - Exhaust Valve Installation1997 - 2001 Honda CR250 - Top End Service - Part 12 - Cylinder Installation

 

Keep Your ’97-’01 CR250 Running Right!

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