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Intake Gasket for Honda GX390 Big Block Clone Intake Gasket for Honda GX390 Big Block Clone

Intake gasket for Honda GX340, GX390 and big block clone engines.

Our Price: $1.95
Cylinder Head Dowel for Honda GX390 Cylinder Head Dowel for Honda GX390

Cylinder head dowel fits Honda GX340, GX390, 420cc, 460cc big block clone engine.

Our Price: $4.00
Copper Exhaust Header Gasket for Honda GX390 Copper Exhaust Header Gasket for Honda GX390

Bullfrog Performance Products copper exhaust header gasket for Honda GX240, GX270, GX340, GX390, GX610, GX620 and GX690.  Will also fit Predator 420cc engines and many other big block clone engines.

Our Price: $5.00
Insulator with Pulse Fitting for Honda GX390 Insulator with Pulse Fitting for Honda GX390

Insulator with pulse fitting for Honda GX390 engines.

Our Price: $8.95
ARP Head Bolt for Honda GX390, 460cc ARP Head Bolt for Honda GX390, 460cc

ARP head bolt fits Honda GX340, GX390, 460cc big block clone engines.  Order a total of 4 bolts for one engine.

Our Price: $9.95
Head Gasket Fits 420cc Big Block Engine Head Gasket Fits 420cc Big Block Engine

This head gasket will fit the Predator 420cc and many other 420cc big block clone engines.

Our Price: $15.00
Bronze Valve Guide Set, 6.5mm ID Sold as Pair Bronze Valve Guide Set, 6.5mm ID Sold as Pair

Bullfrog Performance Products bronze valve guide set will fit the Honda GX340, GX390 and many other big block clone engines with factory diameter valve stem size of 6.5mm.  Our bronze valve guide will outperform in longevity and performance over the factory steel guide.  Has closer to the same heat expansion rate as aluminum head for a more stabil valvetrain operation.  These are sold as a pair of bronze guides.

Our Price: $16.00
Copper Head Gasket, Honda GX390, 460cc, 500cc Big Block Copper Head Gasket, Honda GX390, 460cc, 500cc Big Block

Copper head gasket available in a variety of bore and thickness ranges for the big block Honda GX390, 460cc, 500cc engines.  Select the gasket below that fits your build:

Our Price: $18.00
Air Filter Adapter, Fits Honda GX340, GX390 Air Filter Adapter, Fits Honda GX340, GX390

Our air filter adapter fits factory carburetor for Honda GX340 and GX390 engines. Also fits 420cc and 460cc engines with stock carburetor.
Be sure to order your air filter and pre-filter along with your air filter oil and cleaner.

Our Price: $21.00
Retainer Kit, Billet Valve Spring Retainer Kit for Honda GX390 Retainer Kit, Billet Valve Spring Retainer Kit for Honda GX390

Bullfrog Performance Products billet valve spring retainer kit fits Honda GX390 big block engines using our stainless steel or titanium valves.

Our Price: $25.00
Stainless Steel Intake Valve for Honda GX390, 460cc Big Block Stainless Steel Intake Valve for Honda GX390, 460cc Big Block

Bullfrog Performance Products stainless steel intake valve fits Honda GX390, 460cc engines. We offer cylinder head machining to install larger valves into the Honda GX390 cylinder head. Select the valve head size you are looking for below. We highly recommend this valve when using high lift aftermarket racing cams to prevent valvetrain failure.
Be sure to include our billet aluminum or titanium valve spring retainer kit with our valve.

Our Price: $25.00
Shaft Mounted Stamped Steel Rocker Arm Set Big Block Shaft Mounted Stamped Steel Rocker Arm Set Big Block

A Shaft-Rocker eliminates the need for a guideplate and prevents the rocker arms from walking side-side. Furthermore, they have considerably more ridgidity than stud rockers.
These have a
1.1:1 Ratio and includes the studs and nuts to install the rockers in your engine.

Our Price: $25.00
Dual Valve Spring Kit for Honda GX390 65 lbs Dual Valve Spring Kit for Honda GX390 65 lbs

Bullfrog Performance Products 65 lb. dual valve spring kit for the Honda GX390  big block single cylinder racing engines.  We highly recommend our 65 lb. kit when using any of our cams with .300" lift and higher.

Our Price: $30.00
Pushrod Kit, Chrome Moly Big Block 6.5" Length x 1/4" OD Assembled Pushrod Kit, Chrome Moly Big Block 6.5" Length x 1/4" OD Assembled

Our chrome moly pushrod kit fits big block Honda GX390 style engines.  Our pushrod kit includes two 6.5" length pushrods with 6mm ball ends (factory size ends) and are 1/4" OD.  These come assembled.

Our Price: $36.00
Pushrod Kit, Chrome Moly Big Block 7" Length Unassembled Pushrod Kit, Chrome Moly Big Block 7" Length Unassembled

Our big block chrome moly pushrod kit includes two chrome moly pushrods 7" Length x 1/4" OD with 6mm (factory ball size) ball ends.  This kit is unassembled on one end so you can cut your pushrods to your required length.

Our Price: $36.00
ARP Head Bolt Kit for Honda GX390, 460cc ARP Head Bolt Kit for Honda GX390, 460cc

ARP head bolt kit for Honda GX340, GX390, and 460cc big block clone engines.  This kit includes 4 ARP head bolts per kit.

Our Price: $38.00
Titanium Valve Spring Retainer Kit Honda GX390 Big Block Titanium Valve Spring Retainer Kit Honda GX390 Big Block

Titanium valve spring retainer kit that fits the big block Honda GX240, GX270, GX340, GX390, 420cc Predator (non-hemi), 460cc Vegas Carts engine (equipped with our stainless steel valves). This titanium valve spring retainer kit includes (2) titanium valve spring retainers and a set of our automotive bead lock style valve locks. Our retainers will fit the single or dual springs out on the market and we also carry them in stock at Bullfrog Performance Products warehouse.

Our Price: $40.00
Cylinder Head, Aftermarket Honda GX390 Cylinder Head, Aftermarket Honda GX390

Aftermarket Honda GX390 big block clone complete cylinder head.  Comes with aftermarket cylinder head, factory valves, factory retainers, stock valve springs, factory pushrod guideplate, stock rocker arm studs, factory rocker arms and adjusting nuts for the rocker arms.

Our Price: $58.00
Stainless Steel Valve and Titanium Retainer Kit GX390 Stainless Steel Valve and Titanium Retainer Kit GX390

Our big valve kit for the Honda GX340 / GX390 includes the following components:


  • 40mm head stainless steel intake valve 3.650" length
  • 33mm head stainless steel exhaust valve 3.650" length
  • Titanium valve spring retainers
  • Automotive bead lock style valve locks
Our kit does require your head to be machined to fit these valve head sizes. We do offer cylinder head machining at our facility and can machine your cylinder head or purchase a fully machined cylinder head from us ready to go.

Our Price: $60.00
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. 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.

Our Price: $145.00
Roller Rocker Arm Set 1.3 Ratio Black Venom for Honda GX390 Roller Rocker Arm Set 1.3 Ratio Black Venom for Honda GX390

Gage Motorsports Black Venom roller rocker arm set fits Honda GX390 engine (non-hemi head).  This set is a 1.3 ratio.

Our Price: $245.00