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Side Cover Gasket, 7 Bolt Side Cover Honda GX390, 420cc Big Block Side Cover Gasket, 7 Bolt Side Cover Honda GX390, 420cc Big Block

Honda GX390 side cover gasket.  Fits all 7 bolt GX390 engines and 7 bolt 420cc big block engines.

List Price: $10.29
Our Price: $8.95
Sale Price: $8.06
Savings: $2.23
Main Jet Performance Upgrade Kit For GX390 and Predator 420cc Main Jet Performance Upgrade Kit For GX390 and Predator 420cc

Our main jet kit is a must for the Honda GX390, Predator 420cc engines that have had the performance K&N style air filter setup installed on the engine. Maximizes the engine for best performance and air fuel ratio.

Our Price: $8.14
Fuel Pump, Aftermarket Walbro Pulse Type Fuel Pump Fuel Pump, Aftermarket Walbro Pulse Type Fuel Pump

Aftermarket Walbro fuel pump for Clone engines, Predator 212cc engines, Ducar small block engines and many big block Honda GX390 engines.

List Price: $11.44
Our Price: $9.95
Sale Price: $8.96
Savings: $2.48
Stock Connecting Rod for Honda GX390 Stock Connecting Rod for Honda GX390

Factory cast aluminum connecting rod for Honda GX390 engine.

List Price: $18.34
Our Price: $15.95
Sale Price: $14.36
Savings: $3.98
Air Filter Adapter for Mikuni 38mm Super BN Carburetor Air Filter Adapter for Mikuni 38mm Super BN Carburetor

Bullfrog Performance Products air filter adapter for Mikuni 38mm Super BN carburetor.

List Price: $38.95
Your Price $27.50
Sale Price: $19.95
Savings: $19.00
Stainless Steel Intake Valve for Honda GX390, 35mm Head Stainless Steel Intake Valve for Honda GX390, 35mm Head

Bullfrog Performance Products stainless steel intake valve for Honda GX390 big block engines. This valve has 35mm head diameter which is stock size for the Honda GX390 engine. We do offer multi angle valve seat machining to get the most flow from this 35mm valve. We highly recommend this valve when using high lift aftermarket racing cams to prevent valvetrain failure.
This valve will give you the required valve spring installed height to get proper spring rate and coil bind clearance when using high lift aftermarket camshafts.

List Price: $25.88
Our Price: $22.50
Sale Price: $20.25
Savings: $5.63
Stainless Steel Exhaust Valve 31mm Head for Honda GX390 Stainless Steel Exhaust Valve 31mm Head for Honda GX390

Bullfrog Performance Products stainless steel exhaust valve for Honda GX390 engines. The stock size exhaust valve is a 31mm head diameter in a Honda GX390. We offer cylinder head machining services to maximize head flow for better performance.
We highly recommend this valve when using high lift aftermarket racing cams to prevent valvetrain failure. Our valve will put your valve spring installed height and coil bind clearances in the proper range when using our billet valve spring retainer kit.

List Price: $25.88
Our Price: $22.50
Sale Price: $20.25
Savings: $5.63
Piston Ring Set, 90mm for Bullfrog Performance Products Forged Piston Piston Ring Set, 90mm for Bullfrog Performance Products Forged Piston

Piston ring set that fits our Bullfrog Performance Products 90mm diameter forged pistons with 1.100" compressrion height.

Our Price: $44.00
Bullfrog Pro Velocity High Performance Air Filter Kit for Honda GX390 Bullfrog Pro Velocity High Performance Air Filter Kit for Honda GX390

Our Pro Velocity high performance air filter kit fits Honda GX340, GX390, Predator 420cc and 460cc big block clone engines. Upgrade your go kart, mini bike or drift trike with our high performance air filter kit. Our kit includes the following items:


  • High flow racing style air filter 4" filter length
  • Foam Pre-Filter
  • Radiused air filter adapter
  • Choke hold bracket

Our Price: $44.95
Tachometer, Vegas Carts 0-8000 RPM Tachometer, Vegas Carts 0-8000 RPM

A great addition to any Big Block Kit or Performance Go-Kart where a sweeping analog Tachometer is desired. This Tachometer has been specifically designed for small engines with a magneto ignition such as the Predator 212cc, GX390 or 420-460cc Clone and V-Twins such as the Briggs Vanguard or Predator 670cc. Hooks up to the Kill-Wire on the ignition coil.

RPMs from 0-8000. This gauge is equipped with a Backlight.

Mounting bracket for steering column and wiring pigtail included.

85mm Diameter (3.33")

Fully Adjustable & Tunable

Excellent Alternative to the EQUUS 8068.


List Price: $57.44
Our Price: $49.95
Savings: $7.49
Billet Intake Manifold 38mm Super BN Carburetor to Honda GX390 Billet Intake Manifold 38mm Super BN Carburetor to Honda GX390

Bullfrog Performance Products exclusive billet intake manifold adapts Mikuni 38mm Super BN carburetors to Honda GX390 big block engines.  Will also adapt the Mikuni 36mm and 38mm round slide carburetors when using our rubber mounting boot.  Our intake has multiple bolt patterns and incorporates our exclusive throttle mounting bracket with our intake design.

List Price: $66.70
Our Price: $58.00
Sale Price: $52.20
Savings: $14.50
Billet Intake Manifold, 38mm Super BN Carburetor to Honda GX390 Billet Intake Manifold, 38mm Super BN Carburetor to Honda GX390

Our billet intake manifold adapts Mikuni 38mm SBN carburetors to your Honda GX390 big block clone engine. This intake will also work with round slide and flat slide carburetors using a boot that bolts to our intake manifold (sold separately). Our billet aluminum intake has an 1/8" npt port for your fuel pump pulse line and includes the throttle cable bracket integrated into the intake.

List Price: $67.79
Our Price: $58.95
Sale Price: $53.06
Savings: $14.73
Mud Motor Exhaust Header for Honda GX390, Predator 420cc Big Blocks Mud Motor Exhaust Header for Honda GX390, Predator 420cc Big Blocks

Long tube loop exhaust header for the Honda GX340, GX390, 420cc Predator, 460cc big block clone engine for mud motor boat application. Header pipe give your engine more low to mid range torque specifically for mud motor boats.

Our Price: $69.95
Titanium Exhaust Valve 6mm Stem, 35mm O.D., 3.650" Length Titanium Exhaust Valve 6mm Stem, 35mm O.D., 3.650" Length

Titanium Exhaust valve for the Honda GX340, GX390, 460cc big block engines. Our titanium exhaust valve has a 35mm diameter head with 6mm diameter stem and is 3.650" overall length. This valve is also DLC coated to prevent wear between guide and seat contact area.
Limited quantity available so get this valve while it is available!

Our Price: $100.00
Titanium Exhaust Valve 6mm Stem, 45mm O.D., 3.650" Length Titanium Exhaust Valve 6mm Stem, 45mm O.D., 3.650" Length

Titanium Exhaust valve for the Honda GX340, GX390, 460cc big block engines. Our titanium exhaust valve has a 45mm diameter head with 6mm diameter stem and is 3.650" overall length. This valve is also DLC coated to prevent wear between guide and seat contact area.
Limited quantity available so get this valve while it is available!

Our Price: $100.00
Billet Valve Cover, Honda GX390 Big Block w/Cooling Fins Billet Valve Cover, Honda GX390 Big Block w/Cooling Fins

Our billet valve cover for the big block engine features our unique integral cooling fins for additional valve spring chamber cooling. Our billet valve cover is the lightest cover on the market and includes a reed valve system built into the cover design. You can throw away your stock valve cover gasket as our cover comes with an o-ring seal that promotes better clamping force and eliminates oil leaks. The other billet valve covers on the market do not have the machining time put into their valve cover to make them work as a bolt on piece. Our cover is taller than the factory valve cover so it will clear any roller rocker arm on the market. You will also receive our custom machined aluminum crankcase breather fittings.

Bullfrog Performance Products billet valve cover fits big block engines listed below:

  • Honda GX240
  • Honda GX270
  • Honda GX340
  • Honda GX390
  • Powerhorse 414cc
  • Vegas Carts 460cc
  • LCT 414cc
Our big block billet valve cover will only fit the wedge style head and it will not fit the hemi heads on Predator 420cc.

List Price: $172.44
Our Price: $149.95
Sale Price: $134.96
Savings: $37.48
Billet Connecting Rod ARC Racing for Honda GX390 4.410" Billet Connecting Rod ARC Racing for Honda GX390 4.410"

ARC Racing billet connecting rod for Honda GX390 engines.  Includes rod bearings and rod bolts.

List Price: $172.44
Our Price: $149.95
Sale Price: $134.96
Savings: $37.48
Valve, Titanium Intake Valve, 42mm Head Diameter Big Block Valve, Titanium Intake Valve, 42mm Head Diameter Big Block

Bullfrog Performance Products titanium valve has 42mm head diameter. Will work in Honda GX390, 420cc, 440cc and 460cc and 500cc big block engines. This valve will require machining to your cylinder head for proper fit. We offer machining services to fit our valve in your cylinder head.

List Price: $172.44
Our Price: $149.95
Sale Price: $134.96
Savings: $37.48
Valve, Titanium Intake Valve, 45mm Head Diameter Big Block Valve, Titanium Intake Valve, 45mm Head Diameter Big Block

Bullfrog Performance Products titanium valve has 45mm head diameter. Will work in Honda GX390, 420cc, 440cc and 460cc and 500cc big block engines. This valve will require machining to your cylinder head for proper fit. We offer machining services to fit our valve in your cylinder head.

List Price: $172.44
Our Price: $149.95
Sale Price: $134.96
Savings: $37.48
Billet Connecting Rod ARC Racing for Honda GX390 4.450" Billet Connecting Rod ARC Racing for Honda GX390 4.450"

ARC Racing billet connecting rod for the Honda GX390.  This rod is 4.450" center to center length and comes with rod bearings and rod bolts.

List Price: $172.44
Our Price: $149.95
Sale Price: $134.96
Savings: $37.48
GX390 Big Block Bored Carburetor 23.5mm Venturi GX390 Big Block Bored Carburetor 23.5mm Venturi

Bullfrog Performance Products big block bored performance carburetor.  Our carburetor is CNC bored to obtain consistant max air flow.  Our carb has extensive carb air horn modifications along with the fuel circuits re-worked for the best transient and wide open throttle use.  Select if you need gas or methanol / alky fuel.

List Price: $171.35
Our Price: $149.00
Savings: $22.35
Forged Dome Piston Kit 90mm Bore, 1.100" Comp Height Forged Dome Piston Kit 90mm Bore, 1.100" Comp Height

Bullfrog Performance Products forged dome piston kit for the Predator 420cc engines.  This forged piston kit is a 90mm standard bore with a 1.100" compression height.  Our piston fits our 4.440" length billet rod or the ARC Racing connecting rods.

List Price: $224.25
Our Price: $195.00
Sale Price: $175.50
Savings: $48.75