The first thing I did after purchasing a used KX250 is perform a compression test with a compression gauge. This test is a good indication of what condition the engine is in. As, you may already know, the top end & reeds are wear items and need to be eventually replaced. Refer to this post on what I found by replacing broken reeds for new VForce3 reeds.

Service Manual

It is always a good idea to have a service manual for your model. The service manual will usually state what the compression value should be.

Tools

• Compression gauge
• Plug wrench (I used a 13/16” box wrench)

When should I replace my top end?

Since I currently have around 200 psi, I plan to do a top end at the end of the season or after I start to see a decrease in compression. I plan to check compression after every ride or few hours. I’m curious to see how fast it will drop.

Wiseco 2-Stroke Piston Kit

I’ve had good luck using Wiseco piston kits to freshen up all the 2 strokes I have owned in the past. Below is the kit I will purchase and install this winter, how-to video will follow. Note: the image is actually a generic image of a 4 stroke piston. Clicking the image will link you to the correct product.

Wiseco 2-Stroke Piston Kit

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