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GX340 & GX390 PERFORMANCE PARTS

 

Air Filter Adapter, 390
Code: 12360
Price: $21.00
Sorry, we are currently sold out of 'Air Filter Adapter, 390'. Please check back later.
Quantity in Basket: none
Fits GX390 & GX340. Precision CNC machined from billet aluminum. Incorporates venturi design. Accepts filter with a 2 7/16" ID.

Main Jet, 390
Code: 20350
Price: $6.00
Available for delivery
Quantity in Basket: none
Choose from the following main jets for the stock GX390 carburetor: 100, 102, 105, 108, 110, 112, 115 & 118

Carburetor, GX390 Bored .925"
Code: 20150
Price: $99.00
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GX390 carburetor bored to .925". Idle circuitry reworked. Great carb for GX390's needing more power.

Carb Insulator w/Vacuum Takeoff
Code: 20660
Price: $10.00
Available for delivery
Quantity in Basket: none
Replaces stock carb insulator. Use the vacuum takeoff to run a fuel pump.

Carburetor Adaptor With Pulse Fitting
Code: 12380
Price: $39.00
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Precision CNC machined from billet aluminum. Very light weight. A section of hose is needed to attach carb (not included). Adapter is 2" in length. Hose mounting surface has a 1 9/16" OD. Drilled and tapped for a pulse fitting to run your fuel pump. Pulse fitting and two mounting bolts included. DuroMax and LCT Powerhorse customers need to use the stock carb insulator with this adapter.

32mm Mikuni Carburetor
Code: 12470
Price: $150.00
Sorry, we are currently sold out of '32mm Mikuni Carburetor'. Please check back later.
Quantity in Basket: none
This high quality Mikuni carburetor works great on modified GX340's and GX390's. This carburetor offers more horsepower and torque over the Honda carburetors along with the adjustability of a performance carburetor. Easy to install due to Mikuni's simple throttle cable setup.

Main Jet for 32mm & 34mm Mikuni
Code: 24710
Price: $6.00
Available for delivery
Quantity in Basket: none
Main jet for 32mm & 34mm Mikuni carburetor. Choose from the following sizes: 175, 180, 185, 190, 195, 200, 210, 220, 230 & 240

Pilot Jet for 32mm & 34mm Mikuni
Code: 24720
Price: $8.00
Available for delivery
Quantity in Basket: none
Pilot jet fits our 32mm & 34mm Mikuni carburetor. Choose from the following sizes: 30, 32.5, 35, 37.5 & 40

ARC Billet Rod, 390
Code: 18310
Price: $145.00
Available for delivery
Quantity in Basket: none
The stock rod is the weak link in your engine. Protect your investment with this high quality rod and bearing set. A must have with all big horsepower and high rpm applications.

Bearings, Replacement for Billet Rod 6272
Code: 18350
Price: $22.00
Available for delivery
Quantity in Basket: none
Replacement bearings for billet rod 6272.

Piston, Forged Flat Top, 390
Code: ASFFT390
Price: $150.00
Quantity in Basket: none
OUT OF STOCK. PLEASE CALL Forged flat top piston comes with wrist pin and clips. Uses factory piston rings (not included). Use a finished bore size of 3.465".

Rings, Standard, 390
Code: 20460
Price: $25.00
Available for delivery
Quantity in Basket: none
Standard ring set for the GX390 piston. Fits the flat top piston listed above.

Rings, File Fit, Standard Bore
Code: 20440
Price: $28.00
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Quantity in Basket: none
Over size rings used for file fit in a standard bore.

Cam, Custom Ground .360" Lift, GX390
Code: AGKCAM360
Price: $168.00
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Quantity in Basket: none
GX390 Racing Cam .360" lift and 260* duration at .050" lift. Hard face welding is used for protection against lobe wear. This is a big cam for the hardcore GX390. Upgraded valve train is required. You may need to clearance the inside of the cam lobes for the crank to pass.

ARC Racing Billet Flywheel, 390 NEW
Code: 18400
Price: $195.00
Available for delivery
Quantity in Basket: none
This billet flywheel is very light at 4.7lbs. ARC flywheels use a Neodymium (rare earth) magnet which is the most powerful magnet on the market. Non-adjustable hub. Use flywheel key to adjust timing. Flywheel does not come with a ring gear. Without the ring gear, you will either have to use a handheld starter, or install the starter cup to be used with the pull starter. Uses stock Honda coil. No need for coil bracket and aftermarket coil. Just bolt-on and go! Very high quality. Must have item for any serious GX340 or GX390.

Cylinder Head, 390, Ported & Milled
Code: 16130
Price: $178.00
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Cylinder head ported and milled. Increased flow and velocity from our porting makes this head an excellent choice for performance and value. Highly recommended performance upgrade for the racer looking to take his/her GX340/GX390 to the next level.

Robertson Straight Header
Code: 24310
Price: $39.00
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New low price on RLV straight headers for the GX390. Accepts 1 5/16" silencer.

Robertson "Supersnake" Header
Code: SM390SUS
Price: $64.00
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Quantity in Basket: none
Robertson "Supersnake" Header (1.050ID x 23"IL). Accepts 1 5/16" silencer.

Retainer & Keeper Set, 390
Code: 16370
Price: $32.00
Available for delivery
Quantity in Basket: none
This retainer and keeper set is designed to be used with our stainless steel 390 valves. Will not work with stock valves.

Valve Lash Caps, 390, OEM Honda
Code: 20620
Price: $10.00
Available for delivery
Quantity in Basket: none
Lash caps help prevent valve wear. They also provide a larger surface area for the rocker arm. Use with stock exhaust retainers on both stock valves. Price includes two lash caps. OEM Honda lash caps.

Retainer for Exhaust Valve, 390
Code: 20180
Price: $5.00
Available for delivery
Quantity in Basket: none
Stock exhaust valve retainer. Use on stock intake valve to accomodate lash cap.

Rev Roller Rockers, 390
Code: 16230
Price: $215.00
Available for delivery
Quantity in Basket: none
Honda (or clone) GX340/GX390 billet roller rocker arms designed and engineered to withstand the valvetrain stress of a modified motor.
  • dyno tested and race proven
  • ratio rockers choose 1.2 or 1.3
  • rocker arm CNC machined from 7000 series alloy
  • low rotational inertia mass due to super light arm design
  • bearing grade brass bushings reduce rotational friction
  • precision ground and hardened roller tip provides ultra smooth rotation
  • ground and hardened alloy steel rocker shaft design eliminates valve train deflection
  • cupped lash adjusters with ARP 12 point fastener

Chromoly Push Rods, 390
Code: 16170
Price: $30.00
Available for delivery
Quantity in Basket: none
Chrome moly push rods are highly recommended when using an AGK racing cam.

Chromoly Pushrods Unassembled, 390
Code: 16180
Price: $30.00
Available for delivery
Quantity in Basket: none
Cut to size chrome moly pushrods. Full size assembled length is 6.680".

Guide Plate, Push Rod
Code: 14360
Price: $12.00
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Quantity in Basket: none
Use this laser cut guide plate to accommodate our chrome moly pushrods. Also use with our 1.3 ratio rocker arms. Not required when using our roller rockers.

Valve Spring, 32lbs
Code: 12400
Price: $10.50
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Quantity in Basket: none
The 32lb valve springs. Recommended for mild motors using stock cam. Change quantity to two if you want two springs.

Valve Spring, 55lbs
Code: 12420
Price: $10.50
Available for delivery
Quantity in Basket: none
55lb single spring. Install height 1.200" with 90 to 95lbs open pressure. Use with mild cams. Do not use on stock cams. Change quantity to two if you want two springs.

Valve Spring, Dual, 50lb
Code: 12410
Price: $15.00
Available for delivery
Quantity in Basket: none
Dual valve spring for high output motors. Install height 1.300" with 50lb seat pressure. 120lbs open pressure. Coil bind at .600". Change quantity to two if you want two outer and two inner springs.

Shim, .029"
Code: 14370
Price: $1.15
Available for delivery
Quantity in Basket: none
Use these shims under the valve spring to obtain proper install height.

Lifter, Stock GX390
Code: 20560
Price: $11.00
Available for delivery
Quantity in Basket: none
Genuine Honda GX390 lifter. Big block motors in the 50hp range are wearing out the stock clone lifters. Use this genuine Honda lifter as a replacement. Sold individually. Change quantity to 2 if you want 2.

Gasket Set, GX390
Code: 20160
Price: $26.00
Sorry, we are currently sold out of 'Gasket Set, GX390'. Please check back later.
Quantity in Basket: none
Engine gaskets set for GX390. Includes head, side cover, valve cover, exhaust and both intake gaskets.

33mm Valve, Stainless Steel, GX390
Code: 16320
Price: $32.50
Available for delivery
Quantity in Basket: none
Head size 2mm over for GX390 exhaust. Works on stock valve seat. Stainless steel, nitride coated with hardened tip. No lash caps necessary. Length is 3.642" to accomodate large lift cams. Shim up rocker arms when using these valves. Must use our retainer/keepers set.

35mm Valve, Stainless Steel, GX390
Code: 16330
Price: $32.50
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Quantity in Basket: none
Stock size head for GX390 intake. Stainless steel, nitride coated with hardened tip. No lash caps necessary. Length is 3.642" to accomodate large lift cams. Shim up rocker arms when using these valves. Must use our retainer/keepers set.

38mm Valve, Stainless Steel, GX390
Code: 16350
Price: $32.50
Sorry, we are currently sold out of '38mm Valve, Stainless Steel, GX390'. Please check back later.
Quantity in Basket: none
38mm valve we use in our big valve cylinder heads. Requires larger seat. Stainless steel, nitride coated with hardened tip. No lash caps necessary. Length is 3.642" to accomodate large lift cams. Shim up rocker arms when using these valves. Must use our retainer/keepers set.