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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
Sale Price: $12.00
Savings: $6.00
Starter Nut for Honda GX390 Starter Nut for Honda GX390

Starter nut for Honda GX340, GX390 and many other big block clones including 420cc Predator, 440cc and 460cc clones.  Uses 3/4" socket drive on end to start engine.

Our Price: $17.95
Sale Price: $13.95
Savings: $4.00
Copper Head Gasket, Predator 670cc 80mm x .032" Thick Copper Head Gasket, Predator 670cc 80mm x .032" Thick

Bullfrog Performance Products copper head gasket fits the harbor freight Predator 670cc 22hp engine.  The cylinder bore size on this gasket is 80mm bore and is .032" thick.  Order 2 for complete engine head gasket replacement.

Our Price: $20.62
Sale Price: $14.95
Savings: $5.67
Copper Head Gasket, Predator 670cc 89mm x .032" Thick Copper Head Gasket, Predator 670cc 89mm x .032" Thick

Bullfrog Performance Products copper head gasket fits the harbor freight Predator 670cc 22hp engine.  The cylinder bore size on this gasket is 89mm bore and is .032" thick.

Our Price: $20.62
Sale Price: $14.95
Savings: $5.67
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
Sale Price: $15.00
Savings: $10.00
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
Sale Price: $30.00
Savings: $10.00
Engine Mount, 460cc Big Block Engine Mount, 460cc Big Block

Bullfrog Performance Products big block engine mount plate will fit 460cc engine base plate dimensions that are longer than the Honda GX390. Machined from billet aluminum and ready to bolt to a Burris Racing BMC541 or BMC542 chassis mounts and many other Burris Racing kart chassis mounts.

THIS MOUNTING PLATE WILL ONLY FIT THE 460cc VEGAS CARTS STYLE ENGINE!

Our Price: $65.00
Sale Price: $38.00
Savings: $27.00
Billet Intake Manifold 38mm Super BN Carburetor to Honda GX390 (long) Billet Intake Manifold 38mm Super BN Carburetor to Honda GX390 (long)

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.

Our Price: $45.00
Sale Price: $38.00
Savings: $7.00
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
Sale Price: $45.00
Savings: $15.00
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
Sale Price: $95.00
Savings: $50.00
Big Block GX390 and 420cc Forged Piston Kit Big Block GX390 and 420cc Forged Piston Kit

These forged piston kits are only available while quantities last! Select your bore size below and compression height we have to offer. We have the big block pistons available in 88mm bore, 88.25mm (.010" overbore), 92.75mm bore which is .030" overbore for the Vegas Carts 460cc blocks.

For reference a 1.100" compression height works with the GX390 4.410" or 4.450" length connecting rods

.900" compression height works with our 4.650" length connecting rod for GX390, 420cc and 460cc engine.

Our Price: $195.00
Sale Price: $95.00
Savings: $100.00
Bullfrog Torq-N-Rev Billet Connecting Rod, Honda GX390 4.650" +.200" Longer Than Stock Bullfrog Torq-N-Rev Billet Connecting Rod, Honda GX390 4.650" +.200" Longer Than Stock

Bullfrog Performance Products Torq-N-Rev billet connecting rod is manufactured from billet 7075 T-6 aluminum.  Our billet connecting rod includes rod bearings and setup with ARP rod bolts. Our billet rod is +.200" longer than stock length of 4.650" center to center length.  Works with our forged big block piston kits with .900" compression height.

Our Price: $159.00
Sale Price: $100.00
Savings: $59.00
Forged Piston Kit Predator 670cc 88mm Big Bore Piston Kit Forged Piston Kit Predator 670cc 88mm Big Bore Piston Kit

Limited quantities on hand!  This is our custom forged piston kit for the Predator 670cc engine in an 88mm bore size.  First and only 88mm bore size for the Predator 670cc engine.  These piston kits we use in our turbocharged boat builds.  Will work with the Performance 670 billet connecting rods.  Get these while we have stock as these are while quantities last!  This is for a set of pistons, rings, circlips, wrist pins for a complete engine.

Our Price: $375.00
Sale Price: $295.00
Savings: $80.00
500cc Big Block Racing Engine, Longblock, No Cam 500cc Big Block Racing Engine, Longblock, No Cam

Bullfrog Performance Products is the first in the industry to offer a 500cc big block racing engine package. We are always innovating and bringing new engine packages to the small engine performance enthusiast. Our 500cc longblock is custom built and comes with the following high quality components:

  • Bullfrog Performance Products custom Big Bore tall deck cylinder block for stroker crank applications
  • Bullfrog Performance Products custom forged piston and low drag ring kit
  • Head Dowels
  • Side Cover 10-Bolt
  • ARP side cover bolt kit
  • Solid side cover dowel pins
  • Dipstick and oil fill cap
  • Cranksaft oil seals made from Viton material for higher operating temperatures
  • Roller main bearings
  • Custom stroker crankshaft
  • Bullfrog Performance Products billet connecting rod kit
  • ARP rod bolts
  • Babbit Rod Bearings
  • Victor Reinz big bore fire ring style head gasket
  • Bullfrog Performance Products custom head package
    • GX390 aftermarket cylinder head
    • Big valve package
    • Custom multi-angle valve job
    • Ported, polished and flow tested head
    • Dual valve spring package
    • Billet valve spring retainer kit
    • Chrome moly pushrod kit
    • Roller rocker arm package
    • ARP head bolt kit
This engine package does not include a camshaft or lifter set. We have many cam grinds available so just email us on what you are looking for or put a note at checkout on what cam you are looking for. We will then send a separate invoice for the cam and lifter kit.

Our Price: $2,495.00
Sale Price: $1,900.00
Savings: $595.00