VERTEX Forged Piston for BETA RR 525 2005-2008

On BETA RR 525 from 2005 to 2008, the VERTEX 2958300 forged piston (Ø 97.94 mm) fits in place of the original part. The piston takes every combustion and passes it on to the connecting rod. Forged rather than cast, it stands up better to thermal shock and high revs: a real asset for an engine pushed hard in racing or tuned.

Specifications

• Brand: VERTEX
• Manufacturer part number: 2958300
• Compression ratio: 11.0:1
• Piston diameter: 97.94 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 : see the selection
• Small end needle bearing : see the selection
• Spark plug : see the selection
• 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 piston come complete?
Yes: piston, pin, circlips and ring(s). The top end gasket kit has to be ordered separately, 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:
BETA RR 525 2008
BETA RR 525 2007
BETA RR 525 2006
BETA RR 525 2005