Hop Up Kit - GX340 - GX390, 420 Predators, and 13/15hp Chinese OHV, Stage 4
The 3 kit starts with package similar to that of the stage 2 kit but adds a Ported and Milled Head with stainless, stainless valves, stud kit, & HD valve train components.
- Race/Open Air Filter & Adapter,
- Choice of Carbs
- Choice of Cams
- Ported Head, Milled .100" (Chinese OHV)
- Stainless valves
- Aluminum Retainers & Split Keepers
- Chrome Moly Pushrods
- Single or Dual Springs
- 8 degree Timing Key,
- Billet Rod +(.040 longer)
- Carb, Head, & Case gaskets
- Stud Kit
- Roller Tip 1.2 Rocker Arms (Optional Aluminum Roller Rockers)
- Optional Header/Exhaust
- Optional Aluminum Flywheel
Picture for reference only and may show optional parts. See above description for actual content.
Header not included unless specified.
Due to head work required, allow 1 week to ship.Note: Use of the Choke Bracket requires use of a stock Honda (or Chinese OHV) "Air Filter to Carb Gasket". This is not included in the kit. You can use the one that came with the motor, or can purchase one at
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 recommended. Stock flywheels, esp "Clone" are prone to failure and very DANGEROUS
Note: UT2s series Hondas (2012 & up) or later have a built in Rev Limiter in the coil and will require a new coil to exceed 4000 rpm. The UT2 coils (4 wire) can only be used with stock flywheels.
If using a Billet Flywheel, you must run a UT1 style coil (single wire).
13/15 Chinese Engines (414, 420, 460) usually have UT1 style coils already. However some Lifans and 420s have a digital ignition and will need a Honda UT1 coil to run t he billet flywheel.