VHM Complete Crankshaft for YAMAHA YZ 125 and FANTIC XX 125 2022-2026

On YAMAHA YZ 125 and FANTIC XX 125 from 2022 to 2026, the VHM AK20283 complete crankshaft fits in place of the original part. The centrepiece of the bottom end, the crankshaft carries the connecting rod and takes every combustion. A tired crank assembly shows up as vibration, noise and, in the end, engine failure.

Key features

• Runs perfectly true: run-out under 0.01 mm (rotational deviation measured with a dial indicator at the end of the shaft), for less vibration.
• Heat-treated flywheels: the crankshaft can be rebuilt several times.
• Inertia and balancing developed for handling and performance.

Specifications

• Brand: VHM
• Manufacturer part number: AK20283
• Engine: 2-stroke

When to replace it?

• Play at the big end (vertical movement of the connecting rod at top dead centre).
• Unusual vibration, dull noise from the bottom end.
• Signs of overheating or seizure on the small-end bearing or the crank pin.

During a bottom end rebuild, or as soon as play appears at the big end. A complete crankshaft saves you having the original crank assembly pressed apart and realigned.

Fitting tips

1. Replace the crankshaft bearings and oil seals at the same time.
2. Before closing the crankcases, check the side play and the run-out. Run-out is the deviation you measure with a dial indicator at the end of the shaft while turning the crankshaft: it shows whether the two flywheels are perfectly aligned. The lower it is, the less the engine vibrates.
3. Close up the engine with a new complete engine gasket kit.
4. Check the gearbox bearings while the cases are split.
5. Tighten the flywheel nut and primary gear nut to the torque given by the manufacturer, then fill up with fresh oil.

Why VHM?

Founded in 1995, VHM specialises in racing engine parts for motocross, road racing and karting. The brand started out with cylinder heads featuring interchangeable combustion chambers, which became its speciality, and then developed crankshafts, connecting rods and gasket kits.

Spare parts and items to plan

• Crankshaft bearings and seals : CENTAURO
• Complete engine gasket kit : MOOSE · TECNIUM
• Gearbox bearings : HOT RODS TBK0064 · HOT RODS TBK0063
• 2-stroke oil : LIQUI MOLY 1 L 3065 · LIQUI MOLY 1 L 3063
• Spark plug : NGK 3530 · NGK 3230

Frequently asked questions

Are the bearings supplied?
No: you'll need the crankshaft bearing and seal kit, the complete engine gasket kit, the gearbox bearings if required, engine oil and a new spark plug.

What does “run-out” mean?
It's the deviation in the crankshaft's rotation, measured with a dial indicator at the end of the shaft. Very low run-out means the flywheels are perfectly aligned: the engine vibrates less and its bearings last longer. It has nothing to do with full-circle flywheels or balancing, which concern the shape and weight distribution of the flywheels.

Compatibility

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

Fits:
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