This upgrade kit with a full 421cc fits plug and play through our specially manufactured combustion chambers
For more durability, we rely on a humane compression ratio in combination with durable Vertex cast pistons or with wiseco forged piston.
The offer is valid for 1 complete Athena cylinder kit including the required upgrade components.
Perfect if you are looking for an upgrade solution that fits, works and is durable.
Scope of delivery:
1x Athena cylinder kit incl. cylinder head and all gaskets required
2x CNC Big Bore Domes 421 (68mm) (Made by PR!)
2x Vertex upgrade pistons (68mm) (also available with Wiseco forged pistons)
Timings:
Outlet: 195°
Transfer port 124°
Pre-discharge: 35°
Boost port: 121°
Crimp edge: 1.1 - 1.2mm (block sealing surface and original cylinder)
These data are with original block and unmachined Athena 392 cylinders. (Due to manufacturing tolerances, these blade values may vary).
Crankshaft available separately!
For further parts or information, please contact us.
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Installation instructions:
Only to be used with a crankshaft with 4mm more stroke and 115mm connecting rod. (58mm stroke)
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Compatibility:
Yamaha Banshee 350 Upgrade
Yamaha RD350 upgrade (note the exhaust flange!) Unlike the RD!
(The engine housing of the 31k and YPVS has a narrower sealing surface under the exhaust).
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Not authorised for road use. This is a performance upgrade that must be approved by the TÜV.
