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Engine, Racing, Open Modified, Honda GX390
Engine, Racing, Open Modified, Honda GX390

Our Price: $1,859.98

Stock Status:(Out of Stock)
Part #: ENG-RAC-GX390-LM

Head Casting (Application)

GX390 Small Port (High Torque, Wide Power)
Large Port (Max HP, High RPM)
Select Piston/Rings

OEM Dished Piston
Aftermarket Cast Flat-Top [$20]
Forged Flat-Top, Std Bore [ $130]
Forged Flat-Top, 90mm Bore [ $220]
Select Carburator

GX390 Bored - Gas
33 Mikuni Pumper - Gas [+$200]
GX390 Bored - Methanol [+$20]
34 Flat Slide Mikuni - Gas Only [+$130]
33 Mikuni Pumper - Methanol [+$260]
Crankshaft Type/Options

OEM Honda Crankshaft
160" Stroker Crank, Cast, Balanced [ $250]
.200" Billet Stroker Crank [ $450]
Select Rocker Arm Type

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

306 HP (Med to large tracks)
306 TQ (Small Tracks)
307 RPM (33mm Carbs or Bigger Carbs)
Select Flywheel

Billet Aluminum
Small Diameter Aluminum (NA with Electric Start)
Billet Aluminum with Digital (PVL) Ignition [ $100]
Add Fuel Tank & Pump Options

Add Factory Gas Tank [+$15]
Add Fuel Pump, Mounting Plate, and Hoses [+$40]
Additional Options

Add Billet Side Cover [+$120]

Add 40mm Intake [+$50]

Extended Starter Nut for Handheld Starter (No Recoil)

Electronic Balance Crankshaft (w/Mallory) [+$135]

Description -

Honda GX390 Race Engine. Highest quality Big Block available.

Engine includes:

  • Open Element Air Filter Assembly,
  • Removal of governor,
  • Advanced Timing,
  • Billet Steel Rocker Arms
  • Billet Rod
  • Billet Flywheel
  • UT1 Coil (w/o Rev Limiter)
  • Full Ported & milled Head,
  • SS Valves (OS on intake)
  • Aluminum Retainers & keepers
  • Dual Springs (Single with TQ cams)
  • Choice of cams
  • Chrome Moly Pushrods
  • ARP Bolt Kit
  • Choice of Carbs
  • Dyno Tested


  • Roller Rockers
  • Mikuni Carbs
  • 90mm Bore
  • Small Diameter Flywheel
  • PVL Ignition
  • Stroker Crankshafts

Engine Size Options:

88mm (Std) Bore, Stock Stroke : 390cc

88mm (Std) Bore, +.160” Stroke : 414cc

88mm (Std) Bore, +.200” Stroke : 420 cc

90mm Bore, Stock Stroke : 407cc

90mm Bore, , +.160” Stroke : 433cc

90mm Bore, +.200” Stroke : 440cc

Filter should be sprayed with K&N type oil, especially in dirt applications. Oil not included click here.

Billet Stokers cranks come with balance shaft

Engines are built to order and take approx 4 to 6 weeks

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