Who We Are
It all started on a warm summer afternoon deep in Northern Wisconsin. Two brothers — Marty and Tom — along with their close friend Isaac, formed their own home-grown go-kart racing league.
Using local trails and improvised circuits as their Grand Prix tracks, the three quickly realized something — stock engines weren’t cutting it. They craved more speed. More torque. More power. And the only way to get it was to build everything themselves.
What started as tinkering in a garage turned into full-fledged high-performance engineering. Every SPX engine is still built by hand, in-house, and tuned for one purpose: extracting every last drop of power.
Who Our Engines Are For
SPX engines and our F1-inspired go-karts are engineered for adults — these are not toys. We build for riders and racers who want maximum output without compromise. Whether it’s a mini bike, a go-kart, or even a racing lawn tractor, our engines deliver more than enough power to satisfy serious builders.
If you’ve bought a kart or mini bike and aren’t sure what to upgrade next, our customizable engine lineup makes it simple:
- Pick your displacement
- Choose your performance upgrades
- Order it ready to run
No wrenching required — just mount the engine and you're ready to rip.
Important Disclaimer
All engines ship without fluids. Customers are required to add their own oil and fuel. Starting an engine without oil will result in catastrophic damage and voids any warranty.
Each engine is test-started before shipping. After testing, all fluids are drained and the unit is packaged for transport. We strongly recommend performing a proper break-in procedure before your first full-power run.