VHM Complete Crankshaft for YAMAHA YZ 85 2019-2026

The VHM AK20235B complete crankshaft is designed for YAMAHA YZ 85 from 2019 to 2026. The crankshaft turns the up-and-down motion of the piston into rotation. In a two-stroke, it also spins inside the crankcase, which acts as a pump: the quality of its balancing, the accuracy of its alignment and the condition of its big end determine vibration, reliability and the way the engine revs.

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: AK20235B
• 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?

Since 1995, VHM has been designing racing engine parts for two-strokes: cylinder heads with interchangeable inserts, combustion chamber inserts, crankshafts and connecting rods. A specialist brand, used to fine-tune an engine's power without transforming it.

Spare parts and items to plan

• Crankshaft bearings and seals : MOOSE
• Complete engine gasket kit : TECNIUM · ATHENA
• Gearbox bearings : HOT RODS
• 2-stroke oil : LIQUI MOLY 1 L · MOTUL 1 L
• Spark plug : NGK 6801 · NGK 3830

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:
YAMAHA YZ 85 2026
YAMAHA YZ 85 2025
YAMAHA YZ 85 2024
YAMAHA YZ 85 2023
YAMAHA YZ 85 2022
YAMAHA YZ 85 2021
YAMAHA YZ 85 2020
YAMAHA YZ 85 2019