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QMB139 50cc Longcase Engine

$479.95

Premium QMB139, 49cc 4-Stroke complete engine, long crankcase version is the top of the line aftermarket replacement engine available in the marketplace. This is the only engine that has earned the Universal Parts stamp for our stringent quality and performance standards.

Engine is set up for PAIR Emissions System. PAIR is an acronym for Pulsed Secondary Air Injection System. It is an emissions control system used to lower HC and CO emissions. It works by allowing air into the exhaust flow.

Premium Quality, Hand Inspected, QC Verified
Output Shaft Length: 122mm
Accommodates 12-13 Inch Wheel Size
Set Up For Drum Brake
Set Up for PAIR Emissions System
8 Pole A/C Stator
69mm Valves
Includes Premium Bando Drive Belt & NGK Spark Plug
Engine Oil: 0.8 Liters
Gear Oil: 0.12 Liters (filling) and 0.10 Liters (changing)
Shipped Dry, Included Oil Not Installed - Do NOT Run Engine Without Adding Specified Amounts of Oil (Bel-Ray Oil Included)
This Engine Only Ships to the Continental U.S.

Please Read The Following Important Notices:

This engine is shipped dry, included oil not installed. Includes 1 Liter of Bel-Ray Gear Saver Hypoid Oil and 1 Liter of Bel-Ray Engine Oil. DO NOT RUN ENGINE WITHOUT ADDING SPECIFIED AMOUNTS OF OIL.
Check oil level after letting the engine idle for a few minutes, add additional oil if needed.
Set Up For Drum Brakes
This Engine Only Ships to the Continental U.S.
This is not the correct engine for Maddog style scooters, it will be too short.

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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.

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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).

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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.

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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.

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QMB139 50cc Longcase Engine

Frequently Asked Questions

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