S410485301023, S410485301024, P400485850351/1, 13077M06800, 9768M06800, BR8ES, PD300A, 2GU-11321-00-00, 2GU-11311-00-00, 2GU-11181-00-00, 2GU-11111-00-0, 3GG-11351-02-00, 2GU-11631-00-94, 2GU-11610-01-00, 93450-17129-00, 93310-316D6-00, 4L0-11633-00-00, BR8-ES000-00-00, B8E-S0000-00-00, 91830-21014-00 99530-10014-00 99510-10114-00, PD909

421cc Athena Big Bore Banshee Top End Kit

No Spacer Needed 4mil Stroker Ready

Unlock serious power from your Yamaha Banshee with this all-in-one top end conversion kit designed for use with a +4mm stroker crankshaft no spacer required! Transform your 68mm Athena 392cc setup into a roaring 421cc beast that delivers instant results and long-term reliability.

Built to Perform No Shortcuts

This kit is engineered to eliminate guesswork. Youll receive:

– Athena 68mm Nikasil-Plated Cylinders (Set)

– 68mm Wiseco Pro Lite Forged Piston Set w/ Rings, Pins, Circlips

– Heavy Duty Wrist Pin Bearings

– Special Cut 68mm Big Bore 4mil Stroker 22cc Domes

– Talon Titanium Cylinder Head Stud Kit

– Cometic Fiber Base Gasket

– Intake Gaskets & Cool Head O-Ring Kit*

– 4x New Cylinder Dowel Pins

– 2x NGK Spark Plugs Just Fire It Up!

*Fits all Pro Design-style heads. Mod Quad heads require a different kitcontact us after purchase if needed.

Port Timing Is Critical Dont Skip It

This 421cc setup must be ported properly. The Athena port timing is made for a 392cc configuration from the factory. Slapping in a thick base gasket is NOT a real fix and WILL rob your Banshee of its true potential and a waste of your money!

We strongly recommend:

– Correcting port timing to match 421cc stroke

– Watching Herr Jugs Racing’s “Banshee Porting 101” for clarity

– Using our in-house porting service for max performance

FAQ

– Will this kit work with my OEM crank?
No. A +4mm stroker crank is required. Hot Rods #4111 is recommended.

– Do I need to port the cylinders?
Yes. This is absolutely necessary to get full performance from your 421cc setup.

– Is porting included?
No, but we offer it in-housecontact us after purchase for pricing.

– Does this fit all Banshee years?
Yes. This kit fits all Yamaha Banshee years and models when used with a 4mil crank.

– Are the parts new?
100% brand new, sealed in original packaging.

Dont let a weak top end hold you back. Upgrade your Banshee the RIGHT way!

– The Best Parts. The Best Performance. The Best Price. BRAPPPPPPPPPP!

LLC