Description
Yamaha Blaster 240 Big Bore Kit with Wossner Forged Piston
Build a stronger, more powerful Yamaha Blaster engine with the Ken OConnor Racing Wossner 240 Big Bore Kit. This complete cylinder package increases displacement using a 72mm Wossner forged piston and a factory Yamaha cylinder.
Unlike inexpensive replacement-cylinder packages, this kit is assembled from quality components selected for serious Yamaha Blaster builds. It provides the major parts needed to convert your YFS200 top end to a 240cc big bore configuration.
What’s Included
- 72mm Wossner forged piston
- Piston rings, wrist pin and circlips
- Factory Yamaha cylinder
- New cylinder head
- Boyesen ports
- Wossner top-end gasket set
- Wossner top-end wrist-pin bearing
- New cylinder studs
Why Choose a Wossner Forged Piston?
The 72mm Wossner piston provides the strength and durability expected from a quality forged piston. It is a dependable choice for performance Yamaha Blaster engines subjected to higher cylinder pressure, increased heat and demanding riding conditions.
More Displacement for Your Yamaha Blaster
Increasing the Yamaha Blaster engine from its original displacement to approximately 240cc provides more displacement for improved torque and power potential. The results will depend on the cylinder setup, exhaust system, carburetor, intake, ignition, compression and final jetting.
This kit is suitable for riders building a stronger trail machine, dune Blaster or performance-oriented Yamaha YFS200.
Built with a Factory Yamaha Cylinder
A factory Yamaha cylinder provides an important advantage over low-cost imported replacement cylinders. OEM Yamaha castings are known for their material quality, consistency and durability, making them an excellent foundation for a serious big-bore engine build.
Professional Setup Is Important
A 240 big bore conversion is a performance engine modification. Proper assembly, piston clearance, ring-gap inspection, compression, carburetor jetting and break-in are essential.
Your existing jetting may not be correct after installing the kit. Always begin with a safely rich carburetor setting and tune the engine for your exact combination and riding conditions.
For help selecting supporting components or planning your Yamaha Blaster engine build, contact Ken OConnor Racing before ordering.
Yamaha Blaster Fitment
Designed for 1988–2006 Yamaha Blaster YFS200 models.
Always confirm the year, engine configuration and compatibility of any aftermarket components before installation.
Why Buy from Ken OConnor Racing?
Ken OConnor Racing is a full-service engine machine shop specializing in two-stroke engine machining, cylinder work, crankshaft rebuilding and complete engine assembly. All machine work and engine services are performed on-site.
Quality. Service. Price. No excuses—just results.
Product specifications
| Specification | Details |
|---|---|
| Vehicle | Yamaha Blaster YFS200 |
| Model years | 1988–2006 |
| Engine type | Air-cooled two-stroke |
| Kit displacement | Approximately 240cc |
| Piston diameter | 72mm |
| Piston construction | Forged aluminum |
| Piston manufacturer | Wossner |
| Cylinder | Factory Yamaha cylinder |
| Cylinder head | New |
| Gaskets | Wossner top-end gaskets |
| Small-end bearing | Wossner top-end bearing |
| Studs | New cylinder studs |
| SKU | OEMSL240 |
Frequently asked questions
Will this kit fit every Yamaha Blaster?
The kit is intended for Yamaha Blaster YFS200 models produced from 1988 through 2006. Contact Ken OConnor Racing if your engine has previously been modified or fitted with an aftermarket cylinder, stroker crankshaft or custom cylinder head.
Is this a true 240 big bore kit?
Yes. The kit uses a 72mm piston to increase the Yamaha Blaster engine to approximately 240cc.
Does the kit include a piston?
Yes. It includes a 72mm Wossner forged piston along with the necessary piston components.
Does the kit include a cylinder head?
Yes. A new cylinder head is included.
Is the cylinder an aftermarket import?
No. This kit uses a factory Yamaha cylinder rather than a low-cost imported replacement cylinder.
Will I need to rejet my carburetor?
Yes, carburetor jetting should be checked after any major displacement or airflow change. The correct jetting depends on your carburetor, exhaust, intake, elevation, temperature and other engine modifications.
Can I use my stock exhaust and carburetor?
Compatibility and performance depend on the complete engine combination. The engine may run with some stock components, but properly matched intake, carburetor and exhaust components will generally allow the big-bore cylinder to perform closer to its potential.
Does Ken OConnor Racing offer installation or engine-building services?
Yes. Ken OConnor Racing is a full engine machine shop offering cylinder machining, crankshaft rebuilding and complete two-stroke engine assembly services.
