Breaking in your nitro engine is very important. It's time consuming and not a lot of fun, but extremely important. If you spend the time to properly break in your engine it will pay off in the long run and you'll be rewarded with longer engine life, more consistent tuning and increased performance.
Once the engine is in you vehicle and the linkage is set, you'll want to preheat the engine with a heat gun or engine heater. Pre heating the engine is very important especially with a new engine or if you're racing in cold weather. Once the engine is between 180-200 degrees you want to prime the engine by plugging the exhaust and bumping the engine on the starter box. Once the fuel is in the carburetor you can install the igniter and start the engine. Once the engine is running you may need to adjust the low speed needle and idle screw. You want to make sure the engine will idle on it's own without applying any throttle. At this point in the process, don't rev the engine at a high RPM. Once the LSN and idle are set so the engine is idling consistently you just need to monitor the engine temp. Try keeping the engine between 180-220 degrees. You may need to keep the heater plugged in to maintain this temperature. You can also wrap the head with foil or a 1/10th tire insert. Tilt the vehicle at an angle to allow the excess fuel to drain from the pipe while idling.
Once the engine has idled for ¾ of a tank you'll want to slowly apply the throttle to push the excess fuel out of the pipe and engine. Make sure the HSN setting is still super rich. At the end of tank one, shut off the engine and make sure the piston is at bottle dead center, remove the heater and let the engine sit for 5-10 minutes or until it's back to room temperature. Then repeat this process three more times.
Once you've heat cycled the engine four times you can move on to the second part of the process. Now it’s time to run the engine in a parking lot or driveway. Again, preheat the engine before starting it. Start driving the vehicle at a low rpm in a figure eight pattern. During this process you'll want to slowly roll the throttle on and off. At the end of the first tank, shut the engine off and make sure the piston is at bottom dead center. Repeat this process three more time. Each time you can slightly lean out the HSN and increase the speed of the figure eight pattern.
The third and final set of the break in process is to head to the local track and start running some laps. Again making sure you preheat the engine before hitting the track. At this point the LSN can be set pretty close to race tune, but you still want the HSN a little on the rich side. You can run the full track configuration, but be a little careful when jumping, not to over rev the engine while it's in the air free revving. Over the course of the next one to two liters of fuel you can slowly lean out the engine so that is at race tune by the time you get to the half-gallon mark.
Flash Point FP01 settings.
LSN: .5mm in from flush
Mid: .1mm in from flush
HSN: 1.3mm in from flush
Idle gap: .5mm
Recommended Exhaust system.
FP2500 FP Tuned Pipe Complete Set (EFRA 2146)