Genuine Tohatsu 0.5mm Oversize Piston Ring 302-00014-0 2.5/3.5HP
302-00014-0
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Tohatsu 0.5mm O/S Piston Ring
Genuine 302-00014-0 | Matches oversize piston 309-00004-0
Genuine Tohatsu 0.5mm oversize piston-ring service part for specified 2.5HP and 3.5HP two-stroke powerheads rebuilt with the matching oversize piston. Correct ring size and end gap are essential for compression and cylinder protection.
Key Features
- ✔ Genuine Tohatsu OEM ring reference
- ✔ 0.5mm oversize specification
- ✔ For the 309-00004-0 oversize piston family
- ✔ Selected 2.5/3.5HP two-stroke applications
- ✔ Restores sealing only when bore and groove dimensions are correct
Technical Specs
| Part type | Piston ring service part |
| Size | 0.5mm oversize / O/S |
| Engine cycle | 2-stroke |
| Power family | 2.5HP / 3.5HP |
| Manufacturer number | 302-00014-0 |
| 4Boats SKU | 302-00014-0 |
Compatibility / Fitment Guide
Verified base engine family: Tohatsu M2.5A2, M3.5A2 and M3.5B2 and Nissan Marine NS2.5A2, NS3.5A2 and NS3.5B2 two-stroke outboards, only where the serial-specific piston/crankshaft diagram lists the exact part number in this listing.
Required combination: use only with a cylinder machined to the specified 0.5mm oversize and the matching piston 309-00004-0. Check ring side clearance and end gap in the actual bore.
Identification rule: read the model and serial plate, then check the correct internal-engine diagram. Similar-looking 309, 3F0, 302, 361 and other numbered parts are not interchangeable by appearance.
Exclusions: not for a standard-size piston/bore; not for 361, 356, 369 or 3B2 engine families; and not for MFS four-strokes.
Part Number Cross Reference
| Tohatsu | 302-00014-0 / 302000140M |
| Matching piston | 309-00004-0 / 309000040M |
| Standard ring (not equivalent) | 302-00011-0 |
| 4Boats SKU | 302-00014-0 |
The 0.5mm O/S marking is a machining size, not a performance upgrade. Standard and oversize rings are not interchangeable.
Frequently Asked Questions
Is this a standard-size ring?
No. It is the 0.5mm oversize service ring.
Which piston matches it?
The matching 309-series 0.5mm oversize piston is 309-00004-0, subject to catalogue confirmation.
How many rings are supplied?
Confirm the quantity from the product photographs/packaging; the OEM catalogue treats 302-00014-0 as the required oversize ring service item.
Must the ring gap be checked?
Yes. Measure end gap in the finished cylinder and side clearance in the piston groove to the service-manual limits.
Note: Incorrect bore size, ring orientation or end gap can cause immediate engine damage; professional measurement and assembly are strongly recommended.
For the products under £150 the shipping is £6.99.
Free delivery for most items over £150.
