I’ve been getting a lot of letters lately asking what is the best way to break in a new engine. Over the years I’ve heard just about every possible opinion concerning this subject. Personally, be it a stock or performance motor, I always do a conservative break-in procedure, since I can’t hurt the mill by taking it easy for the first 1,000 miles. That said, here’s what I do.

On the initial start-up, let the engine run at 1200-1300 rpm, which is a fast idle, until the rocker boxes get warm. Resist the urge to crack the throttle, since the head gaskets are susceptible to failure at this stage. While the engine is running, make sure the oil pressure is normal, there are no leaks, and oil is returning to the oil tank. Then shut down the engine and let it get cool to the touch. When you start the motor back up let it run until the cylinders become warm/hot to the touch, then shut down and let it cool. Repeat this procedure three or four times, each time letting the motor get slightly hotter. In the final run, gently vary the rpm continuously from idle up to 2500. After letting the motor cool down again, you’re ready to start the 1,000-mile break-in.

The first 50 miles are the most critical for the rings and pistons, so avoid conditions that can cause overheating, such as riding in stop-and-go traffic or pulling a heavy load. Do not exceed 2500 rpm, or 50 mph during this time. Do not lug the motor, which is letting the revs drop under 2000 when under a load. You can now set the idle speed and mixture, as well as change the other fuel settings, but only do so if the engine is not running properly. Do not do power runs! Ride the bike around town, shifting often to vary the rpm and stay out of traffic. Take it easy with the throttle and keep the load to a minimum. After the first 50 miles, change the oil and filter, and check for fuel, oil, or exhaust leaks.

During the next 500 miles, bring the revs up to 3500 rpm (about 60 mph), which is the normal shift point for most people, for short periods of time. Continue to vary the engine’s rpm, while avoiding overheating, lugging, and steady speeds. Once these 500 miles are done, change the oil and filter again.

With 550 miles on the motor, you can be a little more aggressive with the throttle during the next 450 miles while running the engine in a normal, but conservative, manner. Don’t whack the throttle wide open, go drag racing, or pull a heavy load. Continue to vary the engine’s rpm, while avoiding overheating and lugging. Definitely ride around town, which gives you plenty of opportunities to go through the gears, bringing the engine up and down its rpm range. Once you’ve got over 1,000 miles on it, the engine is fully broken in. Go have some fun!

See you on the road.

Chris Maida
Editor
chrism@americanironmag.com