VERTEX Piston Kit for TM RACING EN 250, MX 250 2000-2009

On TM RACING EN 250, MX 250 from 2000 to 2009, the VERTEX 22654D piston kit (Ø 66.36 mm) fits in place of the original part. At the heart of the top end, the piston soaks up the heat and pressure of every explosion. As it wears, the rings no longer seal against the cylinder: compression drops, power drops with it, and the risk of seizure goes up.

Specifications

• Brand: VERTEX
• Manufacturer part number: 22654D
• Compression height: 37.9 mm
• Piston pin diameter: 18 mm
• Rings: 1 x 1 mm
• Size: D (check that it matches your cylinder)
• Piston diameter: 66.36 mm

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. 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.
5. Reassemble with a new top end gasket kit and tighten the cylinder head in a criss-cross pattern to the manufacturer's torque.
6. Break the engine in: warm it up gently, vary the revs and avoid sustained full throttle for the first hour.

Why VERTEX?

Founded in Italy in 1953 as a workshop making parts for agricultural engines, Vertex now makes its entire production in Cadelbosco Sopra, near Reggio Emilia, on CNC machines. Since 1996 Vertex has been KTM's official original-equipment piston supplier: its pistons are fitted as standard to many KTM, Husqvarna and GasGas bikes.

Spare parts and items to plan

• Piston rings : VERTEX
• Top-end gasket kit : VHM SK33000.VITON · VHM SK33000
• Coolant : MOTUL 1 L · MOTUL 20 L
• 2-stroke oil : LIQUI MOLY 1 L · MOTUL 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.

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.

Compatibility

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

Fits:
TM RACING EN 250 2009
TM RACING EN 250 2008
TM RACING EN 250 2007
TM RACING EN 250 2006
TM RACING EN 250 2005
TM RACING EN 250 2004
TM RACING EN 250 2003
TM RACING EN 250 2002
TM RACING EN 250 2001
TM RACING EN 250 2000
TM RACING MX 250 2009
TM RACING MX 250 2008
TM RACING MX 250 2007
TM RACING MX 250 2006
TM RACING MX 250 2005
TM RACING MX 250 2004
TM RACING MX 250 2003
TM RACING MX 250 2002
TM RACING MX 250 2001
TM RACING MX 250 2000