The Stage 4 kit starts with package similar to that of the stage 3 but adds a Ported and Milled Head with stainless, stainless valves, stud kit, & HD valve train components. This kit allows up to 35+ HP out of a 420 Engine. This kit is for OHV engines and will not fit Hemis.

Includes:

• Fully ported and milled race head (genuine Honda Core)
• High Torque Genuine Honda Core (The Best!!)
• High Flow 36mm / 31mm Valves with lash caps
• Dual Springs with titanium retainers
• 307 Race Cam
• Black Venom Aluminum Roller Rockers
• Valve Cover Spacer
• Chrome Moly Pushrods
• Choice of Carbs (or use your own)
• 90mm Forged Flat Top Piston with rings
• Billet Rod +.040
• Offset Timing Key
• Carb, Insulator, Head, & Case gaskets
• ARP Bolt Kit

This kit only fits 414 & 420cc (90mm) Engines.

Picture for reference only. See above description for actual content.

Due to head work required, allow 1 week to ship.

Filter should be sprayed with K&N type oil, especially in dirt applications. Oil not included click here

These kits are intended for experienced engine builders. Some clearancing, fitment, or other engine building "tricks" may be needed.

Billet Aluminum flywheel REQUIRED