May 9, 2007
For years and years we’re told by older mechanics to “follow the MFG’s owners manual for new engines break-in!”. Yet we’ve always heard through the grapevine from racers and others that, the harder you break them in the better (or at least within reason). Well, the guys at Motorman have something to say (and show) about the MFG’s recommendations for engine break in. So you be the judge on this and let us know of your experience. 
Although these pistons came out of engines which were raced for a full season, they weren’t set-up with any special clearances or other preparation. These engines were never worked on prior to being raced and were totally stock. The only difference was the break in method they used…The one on the right was broken in as per MotoMan’s instructions. The one on the left was broken in exactly according to the owner’s manual. The resulting leaky rings have allowed pressure to “blow by” down into the crankcase on acceleration, and oil to “suck-up” into the combustion chamber on deceleration. Motorman’s information is well written and very clear, so take the time to visit their site and learn something….we all can stand for some more “learnin’”.
