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  Hop Up Kit - GX340 - GX390, 420 Predators, and 13/15hp Chinese OHV, Stage 2/3

Our Price: $409.99

Stock Status:In Stock
Part #: STAGE3KIT340-390

Choose Engine Type

420 Predator [+$30]
Select Carburator

GX390 Bored - Gas
GX390 Bored - Methanol [+$20]
34 Flat Slide Mikuni - Gas Only [+$100]
33 Mikuni Pumper - Gas [+$210]
33 Mikuni Pumper - Methanol [+$260]
GX390 Marine Carb [+$30]
Header & Exhaust Options

No Exhaust
Add Header [+$40]
Add Header, Muffler, and Clamp [+$75]
Select Rocker Arm Type

Reinforced 1.1
1.2 Billet Roller Tip, includes CM Pushrods & Guide Plate [+$90]
Roller (includes spacer) [+$200]
Select Camshaft

280 RPM (Med to large tracks, 7500 )
280 TQ (Hi Torque, Small tracks, 6000 rpm)
280 Marine (Super Low end,5000 rpm)
Select Flywheel Type

No Flywheel
Add Aluminum Flywheel - Recoil Start [+$180]
Add Aluminum Flywheel - Electric Start (GX390 Only) [+$220]
Additional Options

Add UT2 Coil w/o Rev Limiter, for UT2 Hondas Only [+$85]

Description -

As step up from the Stage 1, this kit is designed to improve the power for the GX340s and GX390s along with improving the durability.


Race/Open Air Filter & Adapter

  • Choice of Carbs
  • HD Valve Springs
  • Offset Timing Key
  • 280 Lift Cam
  • Reinforced Rockers
  • Billet Rod
  • Carb and Side Cover Gaskets
  • 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.

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

Aluminum or Honda flywheel recommended. Stock flywheels 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.

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