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Hop Up Kit - GX240 - GX270 and 8/9hp Chinese OHV, Stage 4

Our Price: $809.99

Stock Status:In Stock
Part #: STAGE4KIT270

Choose Engine Type

301 Predator with small journal cam
301 Predator & LCT with large journal cam [ $40]
Head Casting (Application)

9hp (GX270 type), Aftermarket casting (Chinese) Casting
GX270 Max HP, Genuine Honda (Large Port) [+$140]
GX270 High Torque, Genuine Honda (Small port) w/32mm Intake [+$30]
Select Carburator

GX390 Bored - Gas
GX390 Bored - Methanol [+$20]
28mm Flat Slide Mikuni - Gas [+$80]
34 Flat Slide Mikuni - Gas Only [+$100]
28mm Flat Slide Mikuni - Methanol [+$100]
33 Mikuni Pumper - Gas [+$210]
33 Mikuni Pumper - Methanol [+$260]
Header & Exhaust Options

No Exhaust
Add Header, Kart & Mini-Bike [+$35]
Add Header, Muffler, and Clamp: Kart & Mini-Bikes [+$80]
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

Reinforced 1.1
Billet Roller Tip 1.2 [+$60]
Select Camshaft

250 Lift Cam
280 HP (Mild cam for larger tracks)
306 HP (Med to large tracks)
280 TQ (Pulling cam)
306 TQ (Small Tracks)
Additional Options

Add UT2 Coil w/o Rev Limiter, for UT2 Hondas Only [+$70]

Description -

For building a serious a GX270 or 301, the 4 kit starts with package similar to that of the stage 3 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
  • Fully ported and milled race head
  • Stainless steel oversize vavles
  • Fully ported and milled race head
  • Chrome Moly Pushrods
  • HD Single or Dual Springs
  • 8 degree Timing Key
  • Billet Rod
  • Carb, Head, & Case gaskets
  • Stud Kit
  • Optional Roller Rockers
  • Optional Header/Exhaust
  • Reinforced Rocker Arms

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


Picture for reference only and may show optional parts. See above description for actual content. Header not included unless specified.

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).

Chinese Engines usually have UT1 style coils already. However some Lifans and 420s have a digital ignition and will need a Honda UT1 coil to run the billet flywheel.

If ordering for a 301, be aware some engines have large Cam Journals (.6357), most 301s have standard cam journals (same as GX270s). If you have a 301, we recommend you measure your cam journals before ordering this. (if in doubt, order the small journal).

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