Wacker Neuson 5000213589 Decomp Assembly

The Wacker Neuson Decomp Assembly is a genuine OEM component designed for the BTS 630, BTS 635, and BTS 635S series cut-off and floor saws. Sourced directly from Wacker Neuson, this assembly matches the original specification exactly, so it installs in place of the worn or failed unit without any guesswork. Compatible across the full BTS 630 and BTS 635 family — including the BTS 630S, BTS 635S, and BTS635s variants — part number is the correct, verified replacement for these machines.

Key Features

• Genuine OEM Decompression Valve Spec — Built to the exact cracking pressure and porting dimensions Wacker Neuson engineered for these engines, ensuring the cylinder vents correctly at startup.
• Direct Drop-In Installation — Threads directly into the original decompression port with no rework needed to the cylinder head or surrounding hardware.
• Broad BTS Series Coverage — Confirmed fitment across the BTS 630, BTS 630S, BTS 635, BTS 635S, and BTS635s cut-off and floor saw models.
• Easier Cold and Warm Starts — A correctly functioning decomp assembly bleeds cylinder pressure at the pull stroke, reducing the force needed to crank the engine and allowing the saw to start cleanly every time.
• Prevents Kickback on Pull-Start — A worn or stuck decompression valve forces the operator to pull against full compression, increasing the risk of cord snap-back and hand or wrist injury; replacing it restores safe starting behavior.

A decompression assembly — often called a decomp valve — is a small spring-loaded valve threaded into the engine cylinder head. When the starter cord is pulled, the valve briefly opens to release a portion of the built-up cylinder pressure, making the engine far easier to turn over by hand. Once the engine fires and reaches running speed, centrifugal force or internal pressure closes the valve automatically so combustion is not affected. A failed decomp assembly — stuck open or stuck closed — either prevents the engine from building enough compression to run, or makes the pull-start dangerously stiff and prone to kickback.

Part Details

Compatibility & Fitment

Verify Before You Order

Fitment is machine-number and revision-specific; always confirm your model and serial number against the fitment list.

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