A proper nitro boat break in procedure is critical for your nitro rc boat engine.
We will first need double check linkages and fuel tubing route. Be certain that when you apply full throttle the carb opens up all the way. When you release throttle on the transmitter so that it rests in the neutral spot, there should be a small gap or opening when looking in to the barrel of the carb. When pushing the throttle lever in to brake position, be certain to set the carb so that it fully closes. Quickly review the fuel tubing route. Fuel line is routed from the pickup of the bottom of the tank to the carb. An inch or two from the carb should be a fuel filter. The tuned pipe should have a pressure fitting attached. Fuel tubing is placed here routed to the top of the fuel tank.
Nitro boat Break In Procedure
Set the needles to the proper setting for break in according to the manual of your engine. Each engine may have different needle settings.
It is recommended for any Nitro Engine break in to first preheat the engine with a hairdryer or heat gun. Apply heat to the cylinder and cylinder head for about a minute or two. Heat in the engine prior to the first run will relieve the cylinder pinch making it much easier to start. The cylinder pinch exists in nitro engines since the cylinder is tapered in shape. As the piston moves towards the top, the engine cylinder decreases in diameter. Heat will allow the cylinder to expand. A newer engine will feel extra tight in this area before break in.
Start the engine by first priming it. Prime the engine by placing your finger on the carb inlet. This will draw in fuel at a quicker rate perfect for priming. With some pull start engines it may be easier by holding your finger over the stinger on the tuned pipe. Now simply pull start the engine or use an electric starter to push fuel towards the carb. Once the fuel reach and enters the carb, the priming step is complete.
Start the engine by turning on the transmitter and reciever. Place the glow plug igniter on and pull start or use an electric starting motor. Once started keep the revs up so that it does not stall.
Before waiting too long toss the boat in to the water keeping the revs up so it does not stall. It may be safer to have some one else toss the boat in while you control it. Drive the boat around while varying the engines rpms from medium-low to medium-high.
After driving the boat around for a few minutes,(2-3) bring the boat in and shut the engine off. After pulling the boat out of the water carefully rotate the engine so that it is not at rest in the “pinch” part of the stroke. Rotate the engine to the spot in the middle where it feels very easy to rotate. The engine can be rotated by the flywheel. The location found is called Bottom Dead Center. Doing this will ensure the engine is not in the “pinch” location as it cools.
Allow the engine to sit and cool to room temperature.
Repeat the process by adding a minute of run time to each run cycle completed. After about 4 or 5 runs there should be a minium of 15-20 minutes total. At this point the engine has successfully completed the break in process.