What’s the Best Piston for KX85 Motorcycles?

best piston for kx85
A very worn piston. Photo courtesy Beatrice Murch via flickr. Used under a CC BY 2.0 license.

Question: My son has a small Kawasaki dirt-bike. He rides around the farm all the time. It now has low compression and is need of a rebuild. What is the best piston for KX85 motorcycles?

I’ve used Wiseco pistons and rebuild kits with great success before.

Wiseco Top End Kit 49MM Electrofusion for Kawasaki KX85
  • Top End kit includes: piston, rings, wrist pin, clips, top end bearing (2 strokes), and gasket kit
  • Each piston is built from race proven designs that are chosen by the top race teams in all forms of racing including Supercross, Motocross, GNCC, Superbike, and more
  • PK kits from Wiseco feature a complete top end gasket kit that gives you everything you need to complete your rebuild from premium materials
  • Dedicated forgings used for superior strength to weight ratio utilizing aerospace alloy
  • High Performance ring kit and alloy pin included with each piston kit for extended life and sustained power

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In my experience, as well, it is hard to go wrong with Vertex pistons and top-end rebuild kits.

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Vertex VTK23429CD Replica Top End Piston Kit
  • Increases power and performance
  • Includes piston, ring(s), pin, circlip
  • Made in Italy

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It is just important to measure your cylinder bore and make sure you get the right sized diameter pistons for the bore.

There are other good brands of pistons for the KX85, as well. I just don’t have a lot of knowledge of them. But I will list other top rated KX85 piston brands: ProX, Wossner, JE Pistons, among others.

Kawasaki KX85 Piston Briefing

Pistons are an integral part of the power plant for KX 85 motorcycles and can impact performance dramatically.

A change in piston size or composition can alter the compression ratio allowing riders to adjust power to their preference.

Each rider may have different needs based on terrain and riding style, a least two options should be considered — high compression and low compression pistons.

This guide is designed to provide an overview of both types of pistons and help choose the best piston for your KX 85.

Bestseller No. 1
Top End Piston & Ring W/Gasket Bearing Kit 48.5mm for Kawasaki KX85 2001-2013
  • Compatible Models:For Kawasaki KX85 2001-2013.
  • Manufacturer Part: 13008-1200, 13001-0006, 13033-1053, 13033-1060
  • Package: 1x Piston, 2x Ring, 1x Bearing, 1X Cylinder Gasket Kit
  • Tips before Purchase: Please carefully check whether your model is applicable to our products before buying. You can refer to the applicable models, pictures and OEM numbers on our page to help you determine your choice.
  • After-Sales Service: If you have any questions about our products during the use or purchase process, you can contact us by Email at any time. Every product purchased from us comes with 24-hour friendly customer service and 1 year product service
Bestseller No. 2
2001-2011 Kawasaki KX85 Dirt Bike Top End Engine Rebuild Kit [Bore Size (mm): 48.45 (Stock)]
  • Bore Size (mm): 48.45 (Stock)
  • 9.2:1 Compression - Nikasil Cylinder
  • Namura Top End Repair Kits Include a Top End Gasket Set, Pistons, Rings, Wrist Pins, Circlips and Silver Coated SCM415 High Strength Chromoly Needle Bearings (Where Applicable)
  • Precision Cut Klingersil Coated Steel Head Gaskets for Better Sealing and High-Temperature Resistance
  • Compatibility: 2001-2011 Kawasaki KX85
Bestseller No. 3
Bestseller No. 4
Top End Gasket Kit fits Kawasaki KX85 KX 85 2001-2013 by Race-Driven
  • Race-Driven Top End Gasket
  • Gaskets are made of high quality material.
  • Kits come with all parts necessary to replace the top end of your gasket.
  • Fits: 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Kawasaki KX85
  • 1032020051
Bestseller No. 5
Bestseller No. 6
Bestseller No. 7
Outlaw Racing Or4245 Top End Gasket Complete Set Kawasaki KX85 2014-2016 Dirt Kit
  • ✅ Exactly what you need to get your bike or ATV rebuilt and running right!
  • ✅ Made to exact OEM specs but with better materials such as Stainless Steel, Fluoroviton, and Teflon so it lasts longer.
  • ✅ Kits will contain the exact gaskets, seals, and O-rings you need to re-assemble your top end after a standard rebuild (Set is for stock bore).
  • ✅ Requires no trimming or modification!
Bestseller No. 8
Tusk Complete Top End Rebuild Kit Pro-Lite Standard (48.5 mm) Wiseco Piston for Kawasaki KX85 2001-2013
  • Tusk Top End Gaskets are made from the highest quality materials available.
  • Kits come complete with head and base gaskets along with other necessary gaskets and parts to rebuild the top end on your motorcycle or ATV. Wiseco Pro-Lite Piston
  • Lightweight forging for instant throttle response and maximum torque
  • Computer engineered piston skirt profiles provide minimal cylinder wall friction
  • Piston kit includes piston, rings, wristpin and circlips.
Bestseller No. 9
Bestseller No. 10

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High Compression Pistons
High compression pistons are designed to provide maximum engine power by concentrating the charge of air and fuel, which increases overall force on the explosion in the cylinder. For experienced riders this type of piston offers more acceleration and higher speeds, but with more vibration due to increased compression ratio. This type should be used when racing as well as long rides on open roads with extended top speeds desired.

Low Compression Pistons
Low compression pistons are intended for less extreme terrain when top speed isn’t as important as having good torque for maneuvering tight corners or riding in varied terrain where ground clearance is often an issue. For recreational or off-road use this type of piston gives you better throttle response in lower ranges at a much reduced cost compared to full race-spec high compressive powerplants. In addition to durability, low compressive piston designs also decrease emissions from exhaust stroke combustion providing extra eco-friendly advantages.

Types of Pistons

Pistons are the most important part of any two-stroke engine and choosing the right one is essential to get the best performance.

There are several types of pistons available for the KX 85 and they each have their own advantages and disadvantages.

Forged Pistons

Forged Pistons are commonly used in high performance motors, thanks to their combination of strength and surface hardness.

The main process for forging of pistons consists of heating the raw material (typically aluminium alloy) until it is malleable. It is then placed in between two tools which shape the material into its desired shape.

This process creates a strong and durable piston, capable of withstanding higher pressures found in more powerful engines.

The main benefit of forged pistons is the increased strength over cast variants; meaning these will generally last much longer when placed under significant force for long periods.

They are less likely to expand due to heat buildup too, which can put strain on other parts of the engine if not managed effectively.

Furthermore, they have better stability when compared to their cast counterparts and can offer better fuel economy due to tighter tolerances when compared to machined pistons.

Finally, they are lighter than their cast counterparts which puts less strain on your bike’s engine components; reducing wear and tear under heavy load conditions and requiring less lubrication at certain points in time while also providing smoother operation over extended periods. With all these benefits combined, it is no surprise why Forged Pistons are such a popular choice for high performance motorcycles like the KX 85!

Cast Pistons

Cast Pistons, also known as Aluminum pistons, are made from aluminum alloy castings. These pistons are a great option for engines that need a lightweight but durable material for the piston, such as in high-performance motorcycles and other off-road applications.

The weight advantage of cast pistons is that they provide high compression ratios and in many cases, higher efficiency at higher RPMs.

There are two main types of cast piston construction: one-piece (direct cut) and two/multi piece assembly (hot skiving).

One-piece, or direct cut cast pistons are cut directly out of a ready formed aluminum block using special tools.

Usually these tools simply consist of cutting heads designed to simplify the cutting process. This casting process often requires simple machining operations to finish the shape of the piston since no additional assembly is required afterward.

Two – or multi – piece cast Pistons are created by joining two or more parts together in order to form a complete piston.

This type of casting allows for much more intricate designs and shapes as well as additional internal engine components such as ports and galleries if required by the engine application.

Generally speaking hot skived or 2-3 piece cast pistons have become popular in modern engines due to their ability for superior cooling characteristics, increased port flow rates and superior strength compared with one-piece direct cut cast pistons.

Cast Piston material might vary depending on the usage requirement (just like any other precision application).

A wide range of available Aluminum Alloys can be used with an even wider range of heat treat applications allowing manufacturers to create a custom solution that works best with their application demands whether it be high RPMs or more demanding loads due to higher boost levels etc.

Some common materials used at foundries would be A356 Aluminum Alloy which offers great resistance against corrosion while providing lower thermal expansion compared with other alloys allowing it great performance even at higher temperature ranges usually encountered when tuning an engine specifically for maximum power gains .

Billet Pistons

Billet pistons are powerful and long-lasting components used in high-performance vehicles such as the KX 85. They are designed to perform specifically to the demands of that vehicle, making them one of the best piston choices for race applications.

Billet pistons provide superior strength and heat transfer, reducing wear on parallel engines by keeping the cylinders even. They also have an enhanced expansion rate, due to their monolithic design, which allows for more consistent power during operation.

With increased longevity compared to broached or forged pistons, billets provide reliable performance with less maintenance. Additionally, they can be custom machined for any size engine and warranty offers further assurance in using them on your KX 85.

Bestseller No. 1
Top End Piston & Ring W/Gasket Bearing Kit 48.5mm for Kawasaki KX85 2001-2013
  • Compatible Models:For Kawasaki KX85 2001-2013.
  • Manufacturer Part: 13008-1200, 13001-0006, 13033-1053, 13033-1060
  • Package: 1x Piston, 2x Ring, 1x Bearing, 1X Cylinder Gasket Kit
  • Tips before Purchase: Please carefully check whether your model is applicable to our products before buying. You can refer to the applicable models, pictures and OEM numbers on our page to help you determine your choice.
  • After-Sales Service: If you have any questions about our products during the use or purchase process, you can contact us by Email at any time. Every product purchased from us comes with 24-hour friendly customer service and 1 year product service
Bestseller No. 2
2001-2011 Kawasaki KX85 Dirt Bike Top End Engine Rebuild Kit [Bore Size (mm): 48.45 (Stock)]
  • Bore Size (mm): 48.45 (Stock)
  • 9.2:1 Compression - Nikasil Cylinder
  • Namura Top End Repair Kits Include a Top End Gasket Set, Pistons, Rings, Wrist Pins, Circlips and Silver Coated SCM415 High Strength Chromoly Needle Bearings (Where Applicable)
  • Precision Cut Klingersil Coated Steel Head Gaskets for Better Sealing and High-Temperature Resistance
  • Compatibility: 2001-2011 Kawasaki KX85
Bestseller No. 3
Bestseller No. 4
Top End Gasket Kit fits Kawasaki KX85 KX 85 2001-2013 by Race-Driven
  • Race-Driven Top End Gasket
  • Gaskets are made of high quality material.
  • Kits come with all parts necessary to replace the top end of your gasket.
  • Fits: 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Kawasaki KX85
  • 1032020051
Bestseller No. 5
Bestseller No. 6
Bestseller No. 7
Outlaw Racing Or4245 Top End Gasket Complete Set Kawasaki KX85 2014-2016 Dirt Kit
  • ✅ Exactly what you need to get your bike or ATV rebuilt and running right!
  • ✅ Made to exact OEM specs but with better materials such as Stainless Steel, Fluoroviton, and Teflon so it lasts longer.
  • ✅ Kits will contain the exact gaskets, seals, and O-rings you need to re-assemble your top end after a standard rebuild (Set is for stock bore).
  • ✅ Requires no trimming or modification!
Bestseller No. 8
Tusk Complete Top End Rebuild Kit Pro-Lite Standard (48.5 mm) Wiseco Piston for Kawasaki KX85 2001-2013
  • Tusk Top End Gaskets are made from the highest quality materials available.
  • Kits come complete with head and base gaskets along with other necessary gaskets and parts to rebuild the top end on your motorcycle or ATV. Wiseco Pro-Lite Piston
  • Lightweight forging for instant throttle response and maximum torque
  • Computer engineered piston skirt profiles provide minimal cylinder wall friction
  • Piston kit includes piston, rings, wristpin and circlips.
Bestseller No. 9
Bestseller No. 10

Affiliate links / Images from Amazon Product Advertising API

Why Use High Quality KX85 Piston?

Improved Performance

Using a piston in a two-stroke engine can produce numerous benefits. Chiefly, the improved compression ratio and enhanced air compression efficiency provides an increase in power and torque, which leads to improved overall performance.

In addition, pistons are effectively designed to minimize internal friction and vibration by reducing the drag between the piston and its surrounding components.

Furthermore, it is beneficial to use a piston that has been machined utilizing advanced technologies as this allows for increased strength and accuracy in the design, leading to better adherence to OEM specifications and standards.

Through these combined measures of advanced technology, higher manufacturing tolerances, minimized friction and fatigue resistance, piston performance will continue to improve over time as modifications have continued.

Increased Durability

The piston in an internal combustion engine is what helps create the necessary pressure needed for fuel to combine with air and be ignited. It also helps transfer the power produced by this mixture to the crankshaft, which then turns it into useful work. An upgraded piston can significantly reduce the risk of engine failure and help increase engine life by improving reliability, performance and durability.

A high-quality piston will feature reinforced walls with a stronger connecting rod than those you find in factory models. This reinforces areas prone to stress and damage, allowing it to operate more efficiently withstanding higher levels of friction. The improved composition also adds to its heat tolerance and wear resistance, along with reducing weight. Furthermore, if your vehicle has been tuned or modified in any way, then an upgrade of your piston can help you achieve even better levels of performance while still remaining within a safe operating range.

The tight tolerances associated with higher quality aftermarket pistons create improved efficiency as well as a reduction in oil consumption caused by blowby or poor sealing rings conditions; this reduced oil consumption alone is a major cause of engine failure in modern pistons due to lack of lubrication causing increased wear on components such as bearings or camshafts. All these benefits come together to provide much greater durability, improved performance, reduced weight and greater fuel economy – increasing the longevity of your engine should you maintain pistons regularly throughout its lifetime.

Improved Reliability

The main benefit of using a piston in your KX 85 is improved reliability and performance. A piston helps to reduce friction, regulate temperatures and increase the life of your engine. It does this by enabling more controlled combustion and faster cycle times during the intake and exhaust phases of each engine cycle.

The air-fuel mixture is also stabilized, allowing for more complete combustion, which means improved power output with smoother operation throughout revs. This means fewer breakdowns due to overheating or misfiring caused by poor compression or unbalanced fuel mixtures.

Furthermore, using a piston also reduces vibration due to its concentric nature, allowing for increased durability without compromising performance.

Find the best piston for KX85 dirt bikes on Amazon.