Description

The Sea-Doo 300 Piston/Ring Kit – +0.25 mm Oversize is an aftermarket engine rebuilding solution designed for cylinders that have been bored out after wear or scoring. It replaces OEM part number 420892738 and is compatible with high-end Sea-Doo models equipped with the 1630 cc 300 hp engine: RXT-X, GTX Limited, RXP-X XRS.

Unlike a standard size kit, this +0.25 mm oversize kit is specifically designed for engine rebuilding after cylinder boring. It guarantees a perfect fit in a reconditioned cylinder and restores the original performance of your Sea-Doo 300.

Technical Specifications

Replaced OEM Part Number: 420892738
Associated Part Numbers: 42091647, 420245436
Oversize: +0.25 mm (for bored cylinder)
Engine Application: Sea-Doo 300 hp (1630 cc)
Content: Complete piston + ring kit (as illustrated)
Condition: New
Type: Aftermarket SBT – OEM replacement
Weight: 0.715 kg
Regulated Substances: None
Installation: Reserved for a qualified technician (prior boring required)

Compatibility

Compatible with Sea-Doo models equipped with the 300 hp (1630 cc) engine that have undergone cylinder reconditioning:

RXT-X 300
RXT-X RS 300
GTX Limited 300
RXP-X 300 XRS

⚠️ This kit is exclusively for cylinders bored to +0.25 mm oversize. Always check your cylinder bore size and original OEM part number before ordering. Installation on an unbored cylinder will result in immediate engine failure.

Why Use a +0.25 mm Repair Oversize?

During a thorough engine overhaul, if the cylinder shows scratches or oval wear, it is necessary to have it reconditioned (bored) by an engine specialist. After boring, the internal diameter of the cylinder is increased by 0.25 mm, making the standard piston incompatible. Symptoms that require boring and a repair oversize are:

Visible scratches on the cylinder wall
Oval or conical cylinder wear
Severe compression loss despite new rings
Excessive and persistent oil consumption

Opting for a +0.25 mm kit rather than a complete engine block replacement allows for substantial savings while restoring the original 300 hp of your Sea-Doo.