Break In Method
Cruiser
Joined: May 2009
Posts: 216
Likes: 1
From: Ohio
It's all about heat. A fresh engine generates more heat till broke in and needs more lubrication. The piston rings literally scrape against the rough cross hatch hone pattern in the cylinder bore. The cross hatch acts as little troughs to carry extra oil down the cylinders for extra lubrication. As engine RPM rises so does the heat as there is more friction. Excessive RPM will increase the heat further where the oil literally burns and dries the oil film faster than the oiling system can replenish it. Scuffing then occurs between the piston and the cylinder walls. Unchecked the piston skirt will expand causing more friction and eventually the piston will grow too large for the bore. The galled piston will seize in the bore. That is why the MOCO recommends an easy break in and not to exceed certain RPM's and speeds for certain mileages. They have to warranty your motor.
S&S and other performance engine builders have "loose fit" specifications where an engine can be ran up to higher RPMs sooner and not have the excessive heat issues.
You can do what you want but after spending $20,000 + on a motorcycle I think I'll do as the factory suggests. They got smart guys that work there with letters after their names like PHD.
S&S and other performance engine builders have "loose fit" specifications where an engine can be ran up to higher RPMs sooner and not have the excessive heat issues.
You can do what you want but after spending $20,000 + on a motorcycle I think I'll do as the factory suggests. They got smart guys that work there with letters after their names like PHD.
Tourer
Joined: Jun 2007
Posts: 279
Likes: 3
From: N. Alabama
I break mine in on the Interstate. Up through the gears, WOT, cool down for a few miles and do it again. About five times and 25 miles should do fine. We break in air cooled lyc and Cont at WOT throttle untill the oil temps start to drop. Works better than the low and slow method. The cross hatch in the cylinders is to seat the rings before the cylinders glaze over. WOT puts more pressure on the compression rings and seats them before the hatch marks are gone and the cylinders glaze over.
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