ATHENA Connecting Rod Kit for FANTIC XE 125, XX 125 and YAMAHA YZ 125 2022-2026

The ATHENA P40321055 connecting rod kit is designed for FANTIC XE 125, XX 125 and YAMAHA YZ 125 from 2022 to 2026. The connecting rod links the piston to the crankshaft and takes the most violent loads in the engine. Its big-end bearing and crank pin wear over the hours: play at the big end is the warning sign of a failure that can wreck the whole engine.

Key features

• High-strength forged connecting rod made in Japan.
• Supplied with crank pin, needle bearing and thrust washers, depending on the application.
• Fits to original dimensions, with no modification.

Specifications

• Brand: ATHENA
• Manufacturer part number: P40321055
• EAN code: 8053300716067
• Weight: 340 g
• Engine: 2-stroke

When to replace it?

• Vertical play at the big end at top dead centre.
• Side play out of tolerance, signs of overheating (bluing).
• Vibration and dull noise from the bottom end.

During a bottom end rebuild, at the intervals in the service manual, and without delay as soon as play appears at the big end.

Fitting tips

1. Replacing a connecting rod means pressing the crankshaft apart and then realigning it: with a dial indicator, you check the run-out, i.e. the deviation in rotation measured at the end of the shaft, which must stay within a few hundredths of a millimetre at most. Leave this job to a properly equipped workshop if you don't have a press and a truing stand.
2. Replace the crankshaft bearings and oil seals at the same time.
3. Check the big-end side play after assembly.
4. Close up the engine with a complete engine gasket kit and tighten to the manufacturer's torque.
5. Check the gearbox bearings, then fill up with fresh oil and fit a new spark plug.

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

• Crankshaft bearings and seals : CENTAURO
• Complete engine gasket kit : MOOSE 808641MSE · MOOSE 811641MSE
• Gearbox bearings : HOT RODS TBK0064 · HOT RODS TBK0063
• 2-stroke oil : LIQUI MOLY 1 L · MOTUL 800 1 L
• Spark plug : NGK

Frequently asked questions

Can I fit the connecting rod myself?
Yes, if you have a press and a crankshaft truing stand; otherwise, an engine workshop can do it for you.

What else should I plan for?
The crankshaft bearing and seal kit, the complete engine gasket kit, the gearbox bearings if required, engine oil and a spark plug.

Compatibility

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

Fits:
FANTIC XE 125 2025
FANTIC XE 125 2024
FANTIC XE 125 2023
FANTIC XE 125 2022
FANTIC XX 125 2025
FANTIC XX 125 2024
FANTIC XX 125 2023
FANTIC XX 125 2022
YAMAHA YZ 125 2026
YAMAHA YZ 125 2025
YAMAHA YZ 125 2024
YAMAHA YZ 125 2023
YAMAHA YZ 125 2022