ATHENA Oil Seal 27.8x55x10 mm for YAMAHA YZ 250 and FANTIC XX 250 2001-2026

The ATHENA 27.8x55x10 mm M731102016002 oil seal is designed for YAMAHA YZ 250 and FANTIC XX 250 from 2001 to 2026. An oil seal (lip seal) seals the gap between a spinning shaft and the casing it passes through: its lip, held against the shaft by a small spring, keeps the oil in and stops water and dirt getting in. It is identified by three dimensions in millimetres: inner diameter (the shaft), outer diameter (the housing) and thickness.

Specifications

• Brand: ATHENA
• Manufacturer part number: M731102016002
• EAN code: 8051757054053
• Rubber-covered outer case
• Profile: FPJ7
• Weight: 30 g
• Engine: 2-stroke

When to replace it?

• Oil weeping or leaking around the shaft.
• Lip hardened, cracked or turned over when you take the seal out.
• A groove worn into the shaft where the lip runs: the new seal must sit on a clean, undamaged surface.
• On a two-stroke, a crankshaft seal that lets air in makes the idle unstable and leans out the mixture.

Replace an oil seal as soon as it leaks, and always whenever you remove it: once a lip has come out of its housing, it never seals properly again. Note the three dimensions marked on the old seal (for example 20 x 32 x 7) or measure the shaft, the housing and the thickness with a caliper.

Fitting tips

1. Drive out the old seal with a seal puller or a screwdriver with a protected tip, without scratching the housing or the shaft.
2. Clean the housing and check the shaft: a scratch or groove under the lip will make the new seal leak.
3. Lightly oil the lip or smear it with grease, then drive the seal in perfectly square with a socket that presses on its outer edge, lip (spring side) facing the oil.
4. Protect the lip from splines, threads or keys as the shaft goes through (adhesive tape or a thin sleeve).

Why ATHENA?

Athena, an Italian company founded in 1973 near Vicenza, designs gaskets, pistons and cylinder kits for motorcycles. An OEM supplier to KTM, Ducati, Fantic, Piaggio and Triumph and a partner of the MXGP world championship, it develops its parts on the test bench and on the track with racing teams.

Spare parts and items to plan

• Grease : MOTUL 400 g

Frequently asked questions

How do I read an oil seal size?
In this order: inner diameter, outer diameter, thickness, in millimetres. A 20 x 32 x 7 seal fits a 20 mm shaft in a 32 mm housing and is 7 mm thick.

NBR or FKM (Viton)?
NBR (nitrile rubber) suits most uses. FKM handles heat better: it's the right choice near the crankshaft or the water pump. The material is listed in the specifications when it is known.

Why would a new seal leak?
Most of the time the shaft is marked under the lip, the seal went in crooked, or the lip folded over as the shaft went through.

Compatibility

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

Fits:
FANTIC XX 250 2023
FANTIC XX 250 2022
YAMAHA YZ 250 2026
YAMAHA YZ 250 2025
YAMAHA YZ 250 2024
YAMAHA YZ 250 2023
YAMAHA YZ 250 2022
YAMAHA YZ 250 2021
YAMAHA YZ 250 2020
YAMAHA YZ 250 2019
YAMAHA YZ 250 2018
YAMAHA YZ 250 2017
YAMAHA YZ 250 2016
YAMAHA YZ 250 2015
YAMAHA YZ 250 2014
YAMAHA YZ 250 2013
YAMAHA YZ 250 2012
YAMAHA YZ 250 2011
YAMAHA YZ 250 2010
YAMAHA YZ 250 2009
YAMAHA YZ 250 2008
YAMAHA YZ 250 2007
YAMAHA YZ 250 2006
YAMAHA YZ 250 2005
YAMAHA YZ 250 2004
YAMAHA YZ 250 2003
YAMAHA YZ 250 2002
YAMAHA YZ 250 2001