I just put a new piston ring on an engine (70cc Puch) with about 700 mi on it. Do I need to break it in, or can I go full throttle?
break-in for new piston ring?
Re: break-in for new piston ring?
If you only have one new ring and the cylinder wall has already lost it's crosshatching (and after 700 miles it's just a faded memory) there's no break-in possible. The way to do it is get get all new rings and re-hone the cylinder, providing fresh crosshatching. Both rings will then have something to wear against and will seat properly and match the bore after the break-in..
btw, regarding the recent interest in the mystery of conflicting opinions about breaking in new setups, I've found a common thread among web-pages regarding how to break-in .. and it's not recommended that it be done by babying the engine.
Aircraft people are kinda particular about engine reliability and power (or they die) and HERE is one of many such examples of an aircraft engineering company's opinion.
"...Pressures in the cylinder only become great enough for a good break-in when power settings above 65% are used...."
"...Full power for takeoff and climb during the break-in period is not harmful; it is beneficial, although engine temperatures should be monitored closely to insure that overheating does not occur. Cruise power settings above 65%, and preferably in the 70% to 75% of rated power range should be used to achieve a good engine break-in..."
"...For those who still think that running the engine hard during break-in falls into the category of cruel and unusual punishment, there is one more argument for high power settings during engine break-in. The use of low power settings does not expand the piston rings enough, and a film of oil is left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates a condition commonly known as glazing of the cylinder walls. When this happens, the ring break-in process stops, and excessive oil consumption frequently occurs..."
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