Max | DIY Racing Go Kart

DIY Racing Go Kart - July 2022

From bare metal to full throttle: a solo design and build project.

Overview

As one of my biggest projects to date, this build consisted of hours of designing, cutting, welding, assembling, and driving! The goal was to cure me of COVID boredom with a go-kart. I set out to build a racing kart based on a shifter kart chassis. Specifically, I drew inspiration from Jacob Sherwood's HAAS Excellor go-kart and aimed to build something similar. I took as many screenshots as I could of his kart and its online listing. Fortunately, I already had a Predator 212 Motor from a previous project and ordered a racing seat from BMI Karts.

Typical racing go-karts are made of round tubing, which wasn’t an option for me due to lack of tools like tubing notchers and benders. Instead, I used 1 1/4" square tubing from Home Depot. I laid out painter’s tape in my garage in the rough shape of the HAAS kart and mocked up the seat and engine layout. One change I made was positioning the engine farther back and closer to the driver, which created a skinnier overall profile and saved space.

Once I finalized the layout, I began cutting and welding the frame. I used the tape templates for marking cuts and ensured strong welds with full penetration. I purchased a spindle set from BMI Karts and welded in 15 degrees of caster and 7 degrees of camber. I also installed a BMI engine mounting plate bolted directly to the frame.

With the main frame complete, I moved to smaller details. I installed billet aluminum racing pedals on 3/16" steel plates welded to the front bar. I added a 44" keyed axle and welded bearing brackets to the rear using engine clearance as a guide. For braking, I used a BMI disk brake kit and welded a bracket for the master cylinder near the brake pedal. I connected the pedal using a clevis pin and ran a brake line to the rear, where I fabricated a custom caliper mount for added rigidity.

The racing seat needed four contact points to the frame, as recommended. I welded two 3/16" bars to the steering hoop support, drilled holes, and bolted the seat using 5/16" button-head screws. For upright supports, I hammered flat ends into 3/4" tubing and added tabs with mounting holes. One end was bolted to the seat, the other to the frame tabs. I also welded two pieces of flat bar to support the lower steering shaft receiver. The shaft itself was a 5/8" steel rod with a welded-in 3/16" plate for tie rod mounts.

With the frame finished, I installed the upper and lower steering shaft receivers using metal lock rings to keep the shaft securely in place. I mounted the spindles with 1/2" bolts and plastic washers to reduce friction and improve steering feel. I fabricated and welded a bracket for the gas tank on the steering hoop, and mounted the wheels, tires, and hubs from BMI Karts.

Before installing the engine, I upgraded it with a Comet 300 Series Torque Converter, a Stage 1 Upgrade Kit from GoPowersports, and removed the governor. These changes increased horsepower to 9HP, a 2.5HP boost. With the engine installed, I added a 1/4" plastic panel wrapped in camo grip tape and secured with custom brackets. To match, I 3D printed purple finishing washers and added a purple steering wheel quick release.

With everything assembled, the kart was ready to rock. I'm really happy with how it turned out—no failures, no broken parts, and consistently great performance.