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Hop Up Kit; GX340 to GX390, 420 Predator, & 13/15hp OHV; Stage 1
Hop Up Kit; GX340 to GX390, 420 Predator, & 13/15hp OHV; Stage 1

Our Price: $35.15

Stock Status:In Stock

Part #: STAGE1KIT390

Carb Jetting

No Jet Included (Customer Must Drill Stock Jet)
Honda UT1 Jetting Jet [+$11]
Honda UT2 Jetting Jet [+$17.6]
420 Hemi Jetting [+$12.1]
13hp Clone Jetting [+$11]
Ignition Coil Option

Add UT2 Coil without Rev Limiter, for UT2 Hondas Only [+$65]
Add Genuine Honda UT1 Coil [+$38]
None Included
Additional Options

Add Twister Cam [+$62]
Header & Exhaust Options

No Exhaust
Add Header- Kart & Mini Bike [+$43]
Add Mud Motor Header & Muffler (GX390) [+$46]

Description -
Stage 1 Hop Up Kit for GX340-GX390, 420 Predator, and 13/15hp OHV
Basic kit for improving the performance of GX390s, 420 Predators, and 13/15hp Chinese OHVs. Simple to install, you can expect significant performance increases!

Kit Includes:
  • Race/Open Air Filter & Adapter
  • Heavy Duty Valve Springs
  • Offset Timing Key
  • Jet for Application (*see notes below*)
  • Optional Ignition Coil
  • Optional Twister Camshaft
  • Optional Header/Exhaust
*Note: UT2 series Hondas (2012 & up) have rev limited coils and will require a new coil to exceed 4000rpm. The UT2 coils (4 wire) can only be used with stock flywheels or 6693 ARC flywheels. If using any other flywheels, you must run a UT1 style coil (single wire). Most 390 “Clone”, 420s, and 460s have UT1 style coils already (however, some Lifans and 420s have a rev-limited digital ignition).

The correct jets must be selected for the application. If unsure, we recommend you check your STOCK main. If stock main is a:
  • #92-97, use a UT1 kit
  • #98-102, use a hemi kit
  • >102, use a UT2 kit
Manufacturers have been known to use different jets on the same models, so it is important to know the stock jet size!

*Picture is for reference only and may show optional parts. See above description for actual content. Header not included unless specified.
Filter should be sprayed with a K&N type oil, especially in dirt applications. Oil not included -
click here.

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