Z50 Hard-Tail Wide Frame Show Build
7.0J wide-frame hard-tail · YX140 electric start · Ruby Red K2 tank show bike
This Z50 wide-frame hard-tail was one of those builds that’s equal parts fun and head-scratching. The Z50 Hard-Tail 7.0J Wide Frame Kit does a lot of the heavy lifting — the stance, the width, and the basic layout are all there — but you still have to get creative to make everything line up and look right. Below is how we put ours together, plus some notes for anyone tackling a similar project.
Front End Setup
We started with CT70 / Z50 / ATC70 Needle-Type Steering Bearings, which drop right in with no modification. The fork from the frame kit slid on and torqued down like it was made for it.
To get that early Z50 vibe, we ran fold-down CT70 K0-style bars on our billet CNC top plate. The height is perfect for adult riders and keeps the cockpit feeling like a mini-bike, not a toy.
For lighting, the Reproduction Z50 K0–K2 Ruby Red Headlight Assembly bolted to the fork brackets with a couple of spacers and slightly longer bolts. It lines up nicely with the tank and looks right at home on the wide frame. We also added a black 12V horn mounted at the fender bracket on the fork leg — clean, compact, and easy to wire.
Brakes and Drivetrain
We stayed with drum brakes front and rear. For this bike’s job — cruising and show duty — drums are more than enough and simpler to adapt than a disc setup. Each brake stay rod was cut to length so the hubs would center correctly. A digital caliper and a grinder were the main tools here.
The front brake cable holder was moved from the fork leg to the brake plate. We made a small angled aluminum bracket, tapped it for a cable adjuster, and bolted it straight to the hub plate. The rear offset arm in the kit handled most of the offset; a small tweak in the rod got it dialed in.
The frame uses a 17 mm pivot for the brake pedal, so we ran a CT70 chrome-steel brake pedal. We added a short sleeve on the pivot, then heated and bent the pedal until everything cleared and lined up. A CT70 extended brake rod was shortened slightly to finish off the linkage.
Chain alignment comes from the kit’s CNC 15 mm sprocket spacer and matching offset sprocket — once those are in, the chain runs straight across the wide hub setup.
Engine and Fitment
Power comes from the YX140cc electric-start semi-auto motor. It fits with about an inch of clearance to the front tire. The included countershaft extension bolts to the 17 mm output shaft after removing the stock sprocket plate, and a slightly shortened spacer took care of the rest. A 420 chain runs straight and true once everything is centered.
The engine-mount foot peg and kickstand kit bolted right up, but the kickstand was way too long for the hard-tail stance. We swapped to a CNC adjustable kickstand and even shortened that — cutting the threaded section out to get the lean angle just right.
Carburetion, Exhaust, and Throttle
For the intake, we used a multi-angle manifold with a Molkt 26 mm carb. Pushing the carb tight against the frame gave the best clearance under the tank. A UNI 45 mm angled filter finished off the setup.
The Z50 Hard-Tail Big Bore Stainless Up Exhaust bolted right up with no modification. It tucks in, clears the tire and pegs, and suits the wide frame perfectly. The tone is crisp, and the flow works great with the YX140.
For controls, the Reproduction CT70 / Z50 K0–K2 throttle assembly needed a shorter cable. We trimmed and resoldered the inner cable, then extended the slide groove slightly in the carb for full throttle travel. Once adjusted, the throttle feels smooth and snappy.
Fenders and Rear Section
We used the Reproduction Z50 K0–K1 chrome fenders. They look a bit small over the 8-inch tires, but that’s part of the charm — like a big guy in a little hat. The front bolted directly to the fork. The rear needed some trimming and reshaping to sit right on the wide frame.
We tied the rear fender into the frame with a front strap and mounted the back of it to the Z50 K1 tail light bracket. A couple of 10 mm spacers under the bracket centered the fender over the wide tire.
Tank and Seat
The Z50 K2 Ruby Red tank went on with the included straps but touched the carb cap slightly. A small tap on the underside of the tank gave us the clearance needed. Once clearanced, it sits perfectly on the frame and ties in nicely with the headlight.
We used a Reproduction K0–K2 seat and lowered it a bit by drilling new mounting holes. Lowering the seat gives the bike that low, cartoonish stance that makes wide Z50 builds so fun to look at.
Wiring and Electrical
Wiring started with our Basic 12V E-start harness. The CT70 12V key switch drops into the frame’s key hole and looks much better than the plastic switch included with the kit.
The YX140 stator is full-wave, so we used the key-on circuit to feed all the lighting. Power runs to the CT70 K0–K1 dimmer switch, the Z50 / CT70 rear tail light (always on), and the CT70 K0 horn switch. All the wiring tucks cleanly under the seat with only the coil visible and grounded to the frame.
Gallery
Parts Used in This Build
Frame, Front End & Controls
- Z50 Hard-Tail 7.0J Wide Frame Kit
- CT70 / Z50 / ATC70 Needle Steering Bearings
- Billet CNC Triple Clamp Mount
- CT70 K0 Fold-Down Bars
- Z50 K0–K2 Ruby Red Headlight Assembly
- Black 12V Horn
Brakes, Wheels & Drivetrain
Engine, Intake & Exhaust
- YX140 Semi-Auto Engine (Electric Start)
- Multi-Angle Intake Manifold
- Molkt 26 mm Carburetor
- UNI 45 mm Angled Air Filter
- Z50 Hard-Tail Big Bore Stainless Up Exhaust
- Engine-Mount Studded Foot Pegs & Kickstand
Bodywork, Seat & Lighting
- Z50 K0–K1 Chrome Fender Set
- Z50 K1 Tail Light Bracket
- CT70 / Z50 Rear Tail / Brake Light
- Z50 K0–K2 Seat
- Z50 K2 Fuel Tank (Ruby Red)
Wiring & Switchgear
Start Your Own Wide-Frame Z50 Build
Thinking about building your own wide-frame show bike or hard-tail cruiser? The Z50 Hard-Tail 7.0J Wide Frame Kit is a solid starting point, and we’re always happy to help with parts selection, fitment tips, and wiring questions.
