Build a Krooztune Supermini YZ65 — longer, taller and ready to go faster.

This build gives a growing rider more room on a Yamaha YZ65 by changing the bike’s wheelbase, ride height and cockpit position, then matching the suspension to the rider and the new setup. It creates a useful step between a standard 65 and an 85-sized bike. The engine stays 65cc.

For Yamaha YZ65 — all year models.

Build order: 1. Swingarm and fork extensions → 2. Seat and tank lift → 3. Handlebar risers and rider triangle → Suspension setup: rear shock and front forks matched to rider weight and component specs.

Step 1 — Extend the swingarm: longer and more stable

The Krooztune Yamaha YZ65 Extended Swingarm adds 30mm to the rear, increasing the wheelbase for a more stable platform as the rider grows. The longer swingarm and its operating angle also change the rear ride height, so the front and rear need to be considered together.

Match the longer rear with the YZ65 Fork Extension Kit. The Yamaha kit uses extended billet fork caps to increase overall fork length and travel, helping establish a taller, balanced chassis.

Yamaha YZ65 Extended Swingarm — All Years  |  YZ65 Fork Extension Kit

Allow for a chain to suit the longer swingarm. Our RK 420MXZ Gold Chain is the option we use for extended 65cc builds; final chain length is set during installation.

Step 2 — Raise the seat and tank

For extra cockpit height and room with the Yamaha YZ65 it requires the Krooztune YZ65 Seat and Tank Lift Kit for this Supermini build.

The kit raises the seat and tank together by 20mm, opening up the cockpit for a growing rider. Raising the seat and tank as a package gives the rider more room while keeping the relationship between those parts consistent.

Krooztune YZ65 Seat and Tank Lift Kit — All Year Models

Step 3 — Lift the bars and complete the rider triangle

This step is easy to miss. When the seat and tank are raised, the handlebars can end up low in comparison. The rider’s position is a triangle between the footpegs, seat and handlebars; those three contact points need to work together.

Our YZ65 Handle Bar Riser Mounts lift the bar mounting position 15mm over standard. Match the bar bend and position to the raised seat and the rider’s size, so sitting, standing and moving around the bike feel natural.

Steps 1–3 build the Supermini YZ65 to the rider’s size and establish the bike’s longer, taller geometry. Then set up the suspension to work with the rider and the finished chassis.

Upgrade the suspension

Rear shock

Upgrade the original KYB shock with the Yamaha YZ65 Shock Upgrade Kit. Choose the base kit or a custom kit tuned to your rider, then match the spring and damping to rider weight, riding level and the extended chassis.

The Yamaha setup uses Yamaha-specific shock components, including the Krooztune high and low speed compression adjuster. Getting the shock right is essential once the longer swingarm changes the way the rear suspension works.

Yamaha YZ65 Shock Upgrade Kit

Front forks: match the setup to the build

With the chassis dimensions established, tune the YZ65’s KYB forks for the rider and the fork extension configuration.

• Yamaha YZ65 Black Series Fork Upgrade Kit — Yamaha-specific fork damping and internal upgrades.
• YZ65 Spring Guide and Hydraulic Bottoming Kit — improved spring guidance and bottoming control. Confirm the contents of your chosen fork package before adding separate components.
• Yamaha YZ65 Black Series Complete Suspension Setup Kit — a combined front and rear upgrade package, with base or custom rider settings.

Tell us the rider’s weight, ability and where the bike is used. We can help match the fork springs, shock spring and damping to the rider and the finished Supermini build.

Building the complete Supermini YZ65?

Contact Krooztune before ordering a full package. Tell us the bike year, rider height and weight, riding level and where the bike is used. We can help confirm the parts, suspension options and package deal for your build.

Longer. Taller. Built around the rider.