METEOR Piston Kit Racing for KAWASAKI KX 85 2001-2013

The METEOR piston kit (Ø 48.44 to 48.47 mm depending on the size class) is designed for KAWASAKI KX 85 from 2001 to 2013. The piston takes the pressure of every combustion and passes it on to the connecting rod, thousands of times a minute. Over the hours it wears, its rings stop sealing properly and the engine loses compression: it starts less easily, pulls less hard and runs hotter.

Key features

• Italian piston manufacturer since 1952.
• Complete kit: piston, ring(s), pin and circlips.

Specifications

• Brand: METEOR
• Manufacturer part numbers: PC2431A, PC2431B, PC2431C, PC2431D
• Piston diameter: A = 48.44 mm, B = 48.45 mm, C = 48.46 mm, D = 48.47 mm
• Available versions: A: ref. PC2431A; B: ref. PC2431B; C: ref. PC2431C; D: ref. PC2431D
• Engine: 2-stroke

Choosing the right size class

The letters A, B, C… are very close diameter grades, one hundredth of a millimetre apart. Measure the cylinder bore with a bore gauge (diameter, ovality and taper) and choose the grade that gives the piston-to-cylinder clearance specified by the manufacturer. As a rule, grade A goes into a new or reconditioned cylinder, grade B into a cylinder that has already been run in. A scored or out-of-spec cylinder has to be reconditioned: you don't make up for its wear with a bigger grade.

When to replace it?

• Loss of power, sluggish pick-up, harder starting: compression is dropping.
• Piston slap on a cold engine, getting more and more noticeable.
• On teardown: vertical scoring on the skirt, stuck or worn rings, thick carbon on the crown.

Replace the piston as set out in your bike's service manual, sooner if you race, and straight away as soon as these symptoms appear. As a Cross-Mania guideline, plan for a new piston every 15 to 30 hours of engine running depending on whether you race or ride for fun. Always measure the cylinder at the same time: a new piston in an oval cylinder won't last.

Fitting tips

1. Clean the cylinder and check it: diameter, ovality, taper and condition of the bore coating.
2. Check the end gap of each ring in the cylinder against the figures in the manual or the manufacturer's instructions.
3. Fit the rings with the mark facing up and each gap correctly located on its locating pin.
4. Check the small-end needle bearing and the pin: at the slightest play, tight spot or marked needle, replace the bearing.
5. Fit the piston with its arrow pointing to the exhaust side, oil the pin and the small end, then fit the circlips without distorting them, gap opposite the notch. A circlip that has been taken out is replaced with new piston pin circlips, never refitted.
6. Reassemble with a new top end gasket kit and tighten the cylinder head in a criss-cross pattern to the manufacturer's torque.
7. Refill the coolant and fit a new spark plug.
8. Break the engine in: warm it up gently, vary the revs and avoid sustained full throttle for the first hour.

Why METEOR?

A piston manufacturer since 1952, Italy's Meteor has supplied original equipment to manufacturers such as Piaggio and Innocenti. Its Meteor Racing division designs pistons for racing engines, both two-stroke and four-stroke.

Spare parts and items to plan

• Piston rings : VERTEX · WISECO 85 L
• Piston pin : WOSSNER
• Top-end gasket kit : ATHENA · CENTAURO 85 L
• Small end needle bearing : ATHENA MNB140180172 · ATHENA MTB220290160
• Spark plug : NGK R6252K · NGK
• Coolant : LIQUI MOLY 1 L · TWIN AIR
• 2-stroke oil : LIQUI MOLY 1 L 3065 · LIQUI MOLY 1 L 3063

Frequently asked questions

Does the kit include the gaskets?
No: the kit contains the piston, rings, pin and circlips. Add a top end gasket kit, because a head or base gasket can never be reused.

Which size should I order?
Measure your cylinder: A, B, C, D correspond to different actual diameters (48.44 to 48.47 mm). Choose the class that gives the piston-to-cylinder clearance specified by the manufacturer.

Can I replace just the rings later?
Yes, as long as the piston and cylinder are still within tolerance. Replacement rings can be ordered on their own, as can the piston pin and the circlips.

Should I replace the small-end needle bearing?
It isn't included. Check it at every piston change and replace the needle bearing at the slightest play or tight spot.

Compatibility

Check the exact model and year of your bike in the list below before ordering.

Fits:
KAWASAKI KX 85 2013
KAWASAKI KX 85 2012
KAWASAKI KX 85 2011
KAWASAKI KX 85 2010
KAWASAKI KX 85 2009
KAWASAKI KX 85 2008
KAWASAKI KX 85 2007
KAWASAKI KX 85 2006
KAWASAKI KX 85 2005
KAWASAKI KX 85 2004
KAWASAKI KX 85 2003
KAWASAKI KX 85 2002
KAWASAKI KX 85 2001