ATHENA Big Bore 70 Cylinder Kit Ø47.6 mm for RIEJU MRT, RR 50, BETA RR 50, APRILIA MX, PEGASO, RX 50 and HM CRE 50 1992-2024

The ATHENA Big Bore 70 Ø47.6 mm P400130100001 cylinder kit is designed for APRILIA MX 50, PEGASO 50, RX 50, RIEJU MRT 50, RR 50, BETA RR 50 and HM CRE 50 from 1992 to 2024. A cylinder that is scored, oval or has a damaged coating loses compression and wears pistons out quickly. Rather than having it rebored and recoated, this kit replaces it with a new, ready-to-fit cylinder.

Specifications

• Brand: ATHENA
• Manufacturer part number: P400130100001
• EAN code: 8050444896938
• Weight: 1.14 kg
• Engine: 2-stroke

When to replace it?

• Cylinder scored or coating flaking after a seizure.
• Ovality or taper out of tolerance when measured with a micrometer.
• You want more torque and power without touching the bottom end.

Measure the cylinder at every piston change. As soon as it falls outside the tolerances in the manual or is scored, it has to be replaced or reconditioned.

Fitting tips

1. Carefully clean the top of the crankcase and cover its opening before removing the old cylinder.
2. Oil the supplied piston and check the ring end gaps before fitting the cylinder.
3. Use new gaskets, either those in the kit or a suitable top end gasket kit, and tighten the cylinder and head in a criss-cross pattern to the manufacturer's torque.
4. Fit a new spark plug and refill the coolant.
5. Break the engine in gently for 3 to 4 hours, as Athena recommends for its cylinder kits.

Why ATHENA?

Founded in 1973 near Vicenza, Athena is an Italian engine gasket specialist that has made its gaskets on its own production lines since day one, as well as a renowned manufacturer of pistons and cylinder kits. The brand supplies original equipment to manufacturers such as KTM, Ducati, Fantic, Piaggio and Triumph, and is a partner of the MXGP motocross world championship.

Spare parts and items to plan

• Piston : ATHENA
• Piston pin : ATHENA S410000304007 · ATHENA S410000304002
• Cylinder head and dome : ATHENA S410105308003 · ATHENA S410130308003
• Spark plug : NGK 3961 · NGK 5722
• Coolant : LIQUI MOLY 1 L · TWIN AIR

Frequently asked questions

What does the kit contain?
The cylinder and its complete piston. Check the photo and the Athena instructions for the gaskets supplied.

Is it road legal?
No: a Big Bore kit increases displacement; it is for closed-course competition only and may change your racing class.

Which spare parts should I plan for?
For the next service: piston, rings, pin, circlips and top end gaskets in the same size as this cylinder.

Compatibility

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

Fits:
APRILIA MX 50 2004
APRILIA MX 50 2003
APRILIA MX 50 2002
APRILIA PEGASO 50 1997
APRILIA PEGASO 50 1996
APRILIA PEGASO 50 1995
APRILIA PEGASO 50 1994
APRILIA PEGASO 50 1993
APRILIA PEGASO 50 1992
APRILIA RX 50 2004
APRILIA RX 50 2003
APRILIA RX 50 2002
APRILIA RX 50 2001
APRILIA RX 50 2000
APRILIA RX 50 1999
APRILIA RX 50 1998
APRILIA RX 50 1997
APRILIA RX 50 1996
APRILIA RX 50 1995
BETA RR 50 2024
BETA RR 50 2023
BETA RR 50 2022
BETA RR 50 2021
BETA RR 50 2020
BETA RR 50 2019
BETA RR 50 2018
BETA RR 50 2017
BETA RR 50 2016
BETA RR 50 2015
BETA RR 50 2014
BETA RR 50 2013
BETA RR 50 2012
BETA RR 50 2011
BETA RR 50 2010
BETA RR 50 2009
BETA RR 50 2008
BETA RR 50 2007
BETA RR 50 2006
BETA RR 50 2005
BETA RR 50 2004
BETA RR 50 2003
BETA RR 50 2002
BETA RR 50 2001
BETA RR 50 2000
BETA RR 50 1999
BETA RR 50 1998
HM CRE 50 2017
HM CRE 50 2016
HM CRE 50 2015
HM CRE 50 2014
HM CRE 50 2013
HM CRE 50 2012
HM CRE 50 2011
HM CRE 50 2010
HM CRE 50 2009
HM CRE 50 2008
HM CRE 50 2007
HM CRE 50 2006
HM CRE 50 2005
HM CRE 50 2004
HM CRE 50 2003
HM CRE 50 2002
HM CRE 50 2001
HM CRE 50 2000
HM CRE 50 1999
RIEJU MRT 50 2024
RIEJU MRT 50 2023
RIEJU MRT 50 2022
RIEJU MRT 50 2021
RIEJU MRT 50 2020
RIEJU MRT 50 2019
RIEJU MRT 50 2018
RIEJU MRT 50 2017
RIEJU MRT 50 2016
RIEJU MRT 50 2015
RIEJU MRT 50 2014
RIEJU MRT 50 2013
RIEJU MRT 50 2012
RIEJU MRT 50 2011
RIEJU MRT 50 2010
RIEJU MRT 50 2009
RIEJU RR 50 2008
RIEJU RR 50 2007
RIEJU RR 50 2006
RIEJU RR 50 2005
RIEJU RR 50 2004
RIEJU RR 50 2003
RIEJU RR 50 2002
RIEJU RR 50 2001
RIEJU RR 50 2000
RIEJU RR 50 1999
RIEJU RR 50 1998
RIEJU RR 50 1997
RIEJU RR 50 1996
RIEJU RR 50 1995
RIEJU RR 50 1994
RIEJU RR 50 1993