PROOTOM Valve Shim Kit 141PCS 7.48mm — 1.20–3.50mm (0.05mm) Carburized Steel for 250F Dirt Bikes

PROOTOM OTOM D7.48mm valve shim kit is a 141-piece, 47-size set (1.20–3.50mm in 0.05mm steps) designed to let you dial valve clearances precisely on 250F off-road four-stroke motorcycles.

Keeping valve clearances within specification is essential for reliable power delivery and long engine life on high-revving off-road 250cc four-strokes. This PROOTOM OTOM shim set gives you a comprehensive range of shim thicknesses and multiple spares per size so you can measure, correct, and re-check clearances without repeated trips to the parts counter. The shims are manufactured from carburized steel for strength and wear resistance and come organized in a compact box for garage or trackside use.

How precise are the shim thickness options?

The kit covers 1.20mm through 3.50mm in 0.05mm increments, providing very fine adjustment steps to match factory specifications. Each of the 47 thicknesses includes three identical shims for 141 pieces total—enough to mix and match for exact clearance and to keep spares on hand.

• 47 distinct thicknesses from 1.20mm to 3.50mm
• 0.05mm increment resolution for fine tuning
• 3 shims per thickness for redundancy and fast changes

Will these shims fit my 250F off-road bike?

The set is intended for Japanese-made 250F four-stroke off-road models such as CRF, KX, RMZ, YZ, and WR250F variants that use a 7.48mm shim diameter. Confirm your engine’s shim diameter before purchase to ensure compatibility.

• 7.48mm shim diameter matches many 250F four-stroke cams
• Compatible with a wide range of Japanese off-road 250 models
• Always verify your OEM spec for diameter and clearance

What is the build quality and durability of these shims?

Shims are made from carburized steel to improve surface hardness while preserving core toughness, helping resist wear under cam-loading conditions. That construction helps maintain stable clearances through multiple service intervals when installed and handled correctly.

• Carburized steel surface hardening for longer life
• Uniform stamping and thickness control for predictable adjustments
• Packaged in a labeled box to prevent loss and simplify selection

How do I use this kit when adjusting valves?

Measure the existing lash with a feeler gauge, calculate the required shim thickness change, and replace the old shim with the correct size from the kit. Reassemble and re-check clearances; the extra shims let you iterate without leaving the workshop for parts.

• Measure clearance at TDC per manufacturer procedure
• Swap shims to reach target clearance using the 0.05mm steps
• Keep spare shims for future adjustments and track repairs

Who this kit is for: this PROOTOM OTOM 141-piece shim kit is aimed at home mechanics, professional tuners, and racers working on Japanese 250F four-stroke dirt bikes who need fine control over valve clearance. If you perform regular valve checks, prepare engines for racing, or want a complete, track-ready selection of shim sizes in one compact box, this set gives you the range and spare pieces to perform accurate, repeatable adjustments without frequent reordering.