METEOR Piston Kit for GAS GAS EC 250 1997-2015

The METEOR piston kit (Ø 66.33 to 66.36 mm depending on the size class) is designed for GAS GAS EC 250 from 1997 to 2015. 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: PC2484A, PC2484B, PC2484C, PC2484D
• Piston diameter: A = 66.33 mm, B = 66.34 mm, C = 66.35 mm, D = 66.36 mm
• Available versions: A: ref. PC2484A; B: ref. PC2484B; C: ref. PC2484C; D: ref. PC2484D
• 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 20 to 40 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 : PROX · WISECO
• Piston pin : WOSSNER CW18 · WOSSNER WP033
• Piston pin clips : WISECO · VERTEX
• Top-end gasket kit : VHM · ATHENA
• Small end needle bearing : PROX · NTN
• Spark plug : NGK
• Coolant : LIQUI MOLY 1 L · TWIN AIR
• 2-stroke oil : LIQUI MOLY 1 L · MOTUL 800 1 L

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 (66.33 to 66.36 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:
GAS GAS EC 250 2015
GAS GAS EC 250 2014
GAS GAS EC 250 2013
GAS GAS EC 250 2012
GAS GAS EC 250 2011
GAS GAS EC 250 2010
GAS GAS EC 250 2009
GAS GAS EC 250 2008
GAS GAS EC 250 2007
GAS GAS EC 250 2006
GAS GAS EC 250 2005
GAS GAS EC 250 2004
GAS GAS EC 250 2003
GAS GAS EC 250 2002
GAS GAS EC 250 2001
GAS GAS EC 250 2000
GAS GAS EC 250 1999
GAS GAS EC 250 1998
GAS GAS EC 250 1997