🎄ORDER EARLY FOR THE HOLIDAYS🚚FREE Shipping over $1,200, FREE Helmet, FREE Gift Card (details)
Cyber Sale
Load image into Gallery viewer, Ready-to-Go Race Head for GX390, 420cc, and 460cc
Load image into Gallery viewer, Ready-to-Go Race Head for GX390, 420cc, and 460cc
Cyber Sale

Ready-to-Go Race Head for GX390, 420cc, and 460cc

  • $195.00
  • $250.00
Select Valve & Spring Combo
Select Amount to be Milled
Head | Guide | Hotrod

Uses aftermarket GX390 style large-port casting. Heads are ported, bead blasted, flowed, and milled. Heads can be fitted with either single or dual springs. Single springs are recommended for 306 and smaller cams; dual springs are recommended for 307 and larger cams. 

Choose a 36 or 40mm Intake Valve, comes with 32mm Exhaust Valve.

Increased milling can increase compression, but at the expense of reliability. ** .120 Not Recommended.

Product Includes:

  • Ported & Bead Blasted Head, Milled to Specs
  • Oversize Stainless Intake & Exhaust Valves
  • Aluminum or Titanium Retainers
  • Split Keepers
  • HD Single or Dual Springs
  • Valve Spring Shims
  • 3-Angle Valve Job 
FAQ Accordion with Animation

Frequently Asked Questions

When will my order be shipped and how long does delivery take?
Orders containing in-stock items typically ship within 3–5 business days. Orders that include assembly will require 7–10 business days to prepare. Please note that during the holiday season (Thanksgiving through Christmas), processing times may be longer due to high order volume. Once your order has shipped, you’ll receive an email with tracking information. Most orders are shipped via Less Than Truckload (LTL) freight and generally arrive within 3–7 business days. Deliveries to remote areas (such as mountains, forests, valleys, or islands) may take longer. You can check the estimated delivery date on the carrier’s website using the tracking number we provide.
How your vehicle is shipped?
Unless otherwise noted, the vehicles we offer are shipped crated or on a pallet and do not come assembled unless you’ve selected our assembly service. Assembly typically requires a few basic tools and mechanical knowledge. If you're not confident in your ability to safely assemble a high-speed off-road vehicle, we strongly recommend selecting professional assembly or having it assembled by a local mechanic.

(Learn More)

Do you offer financing?
Yes. Buy-now-pay-later financing is available with our preferred partner, BreadPay® (please see their icon under product pricing for details).

(Learn More)

How can I get assistance if I have question on products?
Please call 888-886-5846 and talk to one of our knowledgeable sales representatives between 9am-3pm PST. Or send us email at orders@gokartsusa.biz.
What warranty is included with my purchase?
You're covered with confidence at GoKarts USA®. Your satisfaction is our top priority. Every purchase comes with manufacturer-backed warranty protection—including up to 12 months of engine coverage—to keep your ride running strong. TrailMaster products also include a 6-month parts warranty for added peace of mind.

(Learn More)

What does 95% or 98% Assembly Mean? What do I need to assemble if shipped in crate?

For shipping safety, most vehicles cannot be fully assembled prior to delivery.

Minor assembly is required—this typically includes installing mirrors, connecting the battery, adjusting handlebars, and other small components. Before operation, please ensure all screws and fasteners are tightened, engine fluids are at proper levels, and the battery is fully charged. Your factory warranty remains valid right out of the box.

(Learn More)


Customer Reviews

Be the first to write a review
0%
(0)
0%
(0)
0%
(0)
0%
(0)
0%
(0)