Piston Pin Compatible With 1999-2025 Yamaha Yz 250 Yz-X 250 18Mm 2-Stroke Wrist Pin 5Cu-11633-00-00

Manufacturer Part Number:
04.1853.3

Cross-Reference OEM Part Numbers:
Suzuki: 12151-37F00
Yamaha: 5CU-11633-00-00
Yamaha: 5CU-11633-10-00
Yamaha: 5UP-11633-00-00

Pin Specifications:
• Outer Diameter: 18mm
• Material: Case-hardened chrome steel

Engine Specifications:
• 249cc 2-Stroke Single Cylinder — Liquid Cooled — Power Valve
• Bore × Stroke: 66.4mm × 72mm

Notes:
• Piston pin (wrist pin) connects piston to connecting rod small end
• Same pin used across Suzuki RM 250 and all Yamaha YZ 250 variants including special editions
• 2-stroke 250cc motocross engines require frequent top-end service
• Always replace circlips when removing pin

Function:
The piston pin (also called a wrist pin or gudgeon pin) is the hardened steel shaft that connects the piston to the connecting rod small end. It transfers combustion force from the piston to the connecting rod while allowing the rod to pivot as the crankshaft rotates. A worn, scored, or loose piston pin causes knocking noise, accelerated bore wear, and potential catastrophic engine failure.

When to Replace:
• During any top-end rebuild (piston, rings, cylinder re-bore/re-plate)
• When pin shows visible wear, scoring, discoloration, or blue heat marks
• When pin has measurable play in the connecting rod small end bearing
• Recommended every 2nd piston replacement even if pin appears serviceable

Installation Notes:
• Always replace piston pin circlips — never reuse old circlips
• Apply assembly oil or premix to pin before installation
• Ensure circlips are fully seated in their grooves — improper seating causes engine damage
• Verify connecting rod small end bearing condition before reassembly
• Competition 2-stroke engines see extreme loads — inspect pin for wear at every rebuild
• Fits all YZ 250 special editions: 50th Anniversary, Monster Energy, YZ-X

PRODUCT NOTICE:
As a parts distributor we mostly sell aftermarket parts (any OEM parts would be noted as such). Aftermarket parts are not sourced from the original vehicle or equipment manufacturer, but are designed to function the same as - if not better than - the original. All parts sold are new.

WARNING - This product may expose you to chemicals which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov