by [email protected] | May 11, 2026 | Performance Guides
Installing a 70cc big bore kit on a QMB139 50cc engine is one of the most popular Chinese scooter performance builds — and easier than it sounds. The QMB139’s vertical cylinder is accessible from the top of the scooter, and most builds are complete in under 3...
by [email protected] | May 11, 2026 | Performance Guides
The most effective performance upgrade for a Chinese 50cc scooter is a big bore kit. By replacing the cylinder and piston with a larger bore, you increase displacement from 50cc to 70cc or 80cc — producing significantly more power. This guide covers how to choose the...
by [email protected] | May 11, 2026 | Performance Guides
A performance exhaust is one of the most impactful bolt-on upgrades for a GY6 scooter — reducing backpressure, improving exhaust scavenging, and freeing up power across the RPM range. This guide walks through the full installation from panel removal to rejetting....
by [email protected] | May 11, 2026 | Performance Guides
Any time you increase airflow through a GY6 engine — new exhaust, big bore kit, performance air filter — you must rejet the carburetor to add more fuel. Running lean is the fastest way to destroy a piston. This guide covers reading the spark plug and dialing in the...
by [email protected] | May 11, 2026 | Performance Guides
Dr. Pulley sliding weights are one of the most recommended CVT upgrades for GY6 scooters — and one of the cheapest. This guide explains why sliders outperform round rollers, how to choose the right gram weight, and how to install them in your GY6 variator. Tools...
by [email protected] | May 11, 2026 | Performance Guides
Upgrading the clutch springs on a GY6 scooter is a simple but effective performance mod. Stiffer springs delay clutch engagement to higher RPM, keeping the engine in its power band longer and improving the feel of acceleration. This guide covers the full clutch spring...
