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Hop Up Kit - GX340 - GX390, 420 Predators, and 13/15hp Chinese OHV, Stage 4



 
Our Price: $908.99

Stock Status:In Stock
Part #: STAGE4KIT390

Head Casting (Application)

13 HP Aftermarket (Chinese) Casting - Large Port
Genuine Honda GX390 UT1, Large Port (Max RPM) [+$30]
Genuine Honda GX390 UT1, Large Port (Max RPM) w/40mm Intake [+$80
Genuine Honda GX390 UT2, Small Port (High Torque) [+$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
None
Add Header [+$40]
Add Muffler and Clamp [+$40]
Select Valve Springs/Retainers

Single HD w/ Aluminum Retainers (Stock thru 306 Cams)
Single HD w/ Titanium Retainers (Stock thru 306 Cams) +$20
Dual w/ HD Aluminum Retainers (307 and up Cams) [+$15]
Select Rocker Arm Type

Billet 1.2 Roller Tip Rockers (included in Kit)
1.2 Roller Rockers (includes Spacer) [+$130]
Select Camshaft

280 RPM (Mild cam for larger tracks)
280 TQ (Pulling cam)
306 TQ (Small Tracks)
306 RPM (Med to large tracks) BEST
307 RPM (33mm Carbs or Bigger Carbs)
320 0807 (not recommended)
Select Flywheel

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 [+$70]

Add Genuine Honda UT1 Coil ( $45)

Qty:
Description -
 

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.

Includes

  • 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

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
.

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