Originally Posted By: SteveSRT8
Originally Posted By: mechtech2
We have to consider the umpteen jillion cars that are broken in perfectly with Mom and Pop driving sedately.
Absolutely truth, but not indicative of whether or not a BETTER way exists.
I was breaking in engines way before the Moto-head was, and if the engine is assembled correctly and tuned properly a hard break in is great. This will result in less blow by, more power, and longer engine life.
It is generally more appropriate to a high performance engine, but applies to anything with a piston ring.
I think the hard break in makes sense. My Harley when we installed the larger pistons and jugs had 175 comp on both,after I ran it out on the highway,from a stop I ran it at just under 3/4 throttle thru 3 gears then downshifted using the engine braking to slow me down back into first again.
I did this for 30 miles to my girls place,let it sit and completely cooled down,then rode it that way again except I integrated 4th gear into the mix cruising for roughly 3 minutes at a time.
When I got back to the shop compression was 195/196 in the cylinders. 10000 miles later and both are just over 195,since my compression tester has a smaller gauge than the shop that originally tested after the build.
Funny thing is when I changed the oil after that run the oil had no fuzz on the magnet and the oil had no glitter. After 500 miles I again changed the oil and same condition but my friend on his brand new 2012 switchback had glitter in his oil,and we changed it at 500 and 1000 miles and both times the oil was glittery however the second time was far less then the first. At 4000 miles there was none we could see.
He broke his bike in softly,and up until around 5000 miles on the bike there was an oily residue in his pipe you could feel with your finger,mine never did. His bike does consume oil between changes. He adds about a quart per oci in half quart increments but mine consumes none,and I'm a whole lot harder on mine than he is,so I expected the opposite to happen.
A hard break in seats the rings better,and the engine braking on the downshift also helps expand the rings into the cylinder walls.
Now I'm not saying drive it like you stole it for 5000 miles what I'm saying it to run it hard for the first 100,since the first 20 are what seats the rings. After the first 100 you can take it a bit easier since the rings are now seated and rpm and heat cycles with now finish off the cams and such.
Hard break in worked for me.
My generators and compressors run full throttle from day one and I've never had a ring seal issue,or an engine issue really from any of them. Any trouble I have had was human error. For whatever that's worth.
