Yamaha Banshee Top End 421cc Kit Athena Cylinder Wiseco Stroker Piston No Spacer
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. You’ll 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
- BPRATV 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 kit—contact us after purchase if needed.
🚨 Port Timing Is Critical – Don’t 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 BPRATV 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-house—contact 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.
Don’t let a weak top end hold you back. Upgrade your Banshee the RIGHT way!
© BPRATV LLC
