MOTO1988 Starter Clutch Kit for Yamaha 350–400 ATVs — One-Way Bearing, Gear Idler & Gasket

MOTO1988 starter clutch kit bundles the one-way bearing, gasket, gear idler, needle bearing and bolts you need to restore reliable starting on compatible Yamaha ATV models.

This complete replacement assembly is designed to match OEM fitment (manufacturer part 5KM-15590-00-00, replacement 1UY-15517-01-00) for a range of Yamaha four-wheelers built between 1987 and 2014. The kit includes the starter one-way bearing, gasket, gear idler, needle bearing and six mounting bolts so you get the major service items together for a quicker install. Use it to address slipping starts, unusual starter noise, or to proactively replace worn starting components during an engine service.

Which Yamaha models and years will this starter kit fit?

This kit is engineered to fit many popular Yamaha ATVs, including Big Bear, Kodiak, Moto 4, Raptor and Warrior models across several model years. Confirm compatibility by checking the part numbers and model designations before ordering.

• Big Bear 350 YFM350FW / YFM350U (1990–1998)
• Kodiak 400 YFM400FW (1994–1998)
• Moto 4 YFM350ER (1988–1995)
• Raptor 350 YFM350R / RSE / RSE2 (2005–2013; some 2005–2007 special editions)
• Warrior 350 YFM350X (1987–2004)

How will replacing the starter one-way bearing and gear idler help my ATV?

Worn starter bearings or idler gears commonly cause grinding, free-spinning, or failure to engage the engine during starting. Replacing these components restores the intended engagement between the starter motor and crank, reducing noise and preventing starter motor damage.

• Restores crisp starter engagement and reduces grinding sounds
• Prevents starter motor overrun and excessive wear
• Includes gasket and bolts for a proper reseal and secure mounting

What comes in the kit and are the parts OEM-equivalent?

The package contains a one-way starter bearing, a gasket, a gear idler, a needle bearing and six bolts, supplying the key items needed for a starter system refresh. The kit lists the manufacturer part number 5KM-15590-00-00 and replacement part 1UY-15517-01-00, intended as a direct-fit aftermarket replacement for those OEM references.

• 1x starter one-way bearing and 1x needle bearing for rotation support
• 1x gear idler to transfer starter drive motion correctly
• 1x gasket and 6x bolts for proper sealing and secure installation

Are there installation notes or support options after purchase?

Before installing, compare the kit parts and OEM numbers against the parts currently on your ATV to ensure fit. MOTO1988 provides customer support via email and offers a one-year product service period; they recommend reviewing model compatibility, pictures and OEM numbers prior to purchase.

• Check part numbers and images against your machine before ordering
• Use standard hand tools; follow torque specs in your service manual
• Contact MOTO1988 customer support for fitment or after-sale questions

Who is this for: This starter clutch and idler gear kit is aimed at Yamaha ATV owners, home mechanics and professional shops maintaining Big Bear, Kodiak, Moto 4, Raptor or Warrior models from the late 1980s through the 2010s. It’s suitable for riders fixing starter engagement problems, performing preventative maintenance, or rebuilding the starter assembly to restore reliable starting performance.