Here's a pic with explanation......
"These Honda F3 pistons show the difference.
Both came out of race bikes, and their owners used the same type of fuel and oil. 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.
Needless to say, this bike was slow !!
It's up to you:
The loss in power from an easy break in and the resulting poor ring seal can be anywhere from 2% - 10% !!"
'85 380 SL (sold)
'85 Carrera Flatnose
'71 280 SL Signal Red/Cognac