WISECO Racer Elite Forged Piston for YAMAHA YFZ 450 2006-2020

On YAMAHA YFZ 450 from 2006 to 2020, the WISECO Racer Elite WRE819M09500 forged piston (Ø 95 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: WISECO
• Manufacturer part number: WRE819M09500
• EAN code: 81909500
• Compression ratio: 14:1
• Piston diameter: 95 mm
• Weight: 430 g
• Engine: 4-stroke

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.
• On a four-stroke: oil consumption, blue smoke and a fouled spark plug.

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 30 to 60 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 the gaps staggered, never letting the ends of the oil control ring overlap.
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. Refill the coolant, fit a new spark plug and change the oil with fresh engine oil and a new filter.
7. Break the engine in: warm it up gently, vary the revs and avoid sustained full throttle for the first hour.

Why WISECO?

Wiseco forges and machines its pistons in Mentor, Ohio (USA), using forging tooling made in-house. A benchmark for forged motorcycle parts, the brand also produces valves, clutch baskets and clutch plates.

Spare parts and items to plan

• Top-end gasket kit : see the selection
• Spark plug : see the selection
• Coolant : LIQUI MOLY 1 L · TWIN AIR
• 4-stroke engine oil : LIQUI MOLY 10W40 1 L · MOTUL 10W50

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:
YAMAHA YFZ 450 2020
YAMAHA YFZ 450 2019
YAMAHA YFZ 450 2018
YAMAHA YFZ 450 2017
YAMAHA YFZ 450 2016
YAMAHA YFZ 450 2015
YAMAHA YFZ 450 2014
YAMAHA YFZ 450 2013
YAMAHA YFZ 450 2012
YAMAHA YFZ 450 2011
YAMAHA YFZ 450 2010
YAMAHA YFZ 450 2009
YAMAHA YFZ 450 2008
YAMAHA YFZ 450 2007
YAMAHA YFZ 450 2006