If you just invested in a high-performance Stage 4 or Stage 5 engine for your mini bike or go-kart, you might be tempted to bolt it on and immediately rip it down the street. Do not do that.
Before a racing engine is ready for the track, it needs to go through a strict break-in process. GPS Racing Engine Builder Paul Crafton explains exactly why heat cycling is critical to your engine's survival and walks through our exact process for breaking in a fresh build.
The main goal of the break-in process is to put heat cycles into the motor. A brand-new engine is full of machined parts that have never interacted under extreme temperatures.
A proper break-in allows all the moving pieces to rub together, expand, and work themselves in uniformly to find their "happy spot." Most importantly, the heat generated during this process is required to properly seal up the piston rings.
Breaking in an engine is a process of patience. Here is how we do it:
The First Heat Cycle: Start the engine, but do not ride it. Let the engine sit and idle. You can change the idle up and down slightly, but the goal is simply to get the engine hot so the components can start seating.
The Cool Down: Turn the engine off and let it cool completely down to room temperature.
Drain the Contaminants: While the engine is still slightly warm from the next cycle, drain the oil. This flushes out any initial metal shavings or contaminants created during the seating process.
Repeat: We highly recommend doing this heat cycle process at least twice.
You cannot use standard motor oil for this process. You need a specialized lubricant designed for high friction. We exclusively use Tillotson Break-In Oil.
Grab a single quart.
Use half a quart for the first heat cycle, drain it, and use the remaining half quart for the second cycle. Do not throw used break-in oil back into the engine!
High-performance builds require a little extra attention during the break-in phase:
Leave the Rockers Loose: Stage 4 and Stage 5 engines use aftermarket rockers made from different materials that expand and contract differently than the engine block. We recommend leaving the valve lash (rockers) slightly loose during the break-in. This allows them to bang around and properly seat into their sweet spot. Always remember to check and reset your valve lash after the engine cools completely!
Break Methanol Engines in on Gas: If you have a Stage 5 methanol racing engine, we highly recommend temporarily swapping the carburetor and breaking it in on standard gas. Gas gets much hotter and builds heat much quicker than methanol. Breaking it in on methanol takes significantly longer and requires you to be extremely careful about washing out the cylinder.
Breaking in a high-performance engine takes time, specialized oil, and careful monitoring. For the price, many of our customers simply prefer to have our professional builders handle it before the engine ever leaves our shop.