I'll back what Aaron has said with my own experiance as an engine builder for many years...(this doesn't mean I've done 2 883-1200 conversions...but rather working as an engine/reconditioner/builder for many years on car, bike, truck, marine and earthmoving motors.)
The longer I'm in this game and the more I learn...the less I know....
I didn't know much about micro-welding untill about 5 years ago...... although I used to run all my engines in stages to "seat" everything and allow them to take the high spots off everything without getting too hot and find their "happy" place (funny, I just re-read the Axtell article mentioned by Aaron and Ron refers the surfaces being "happy" together... so I'm not the only one
I use a very similar technique to what Aaron described and that's running the motor for small periods, progressively longer each time and allowing time to cool completely between runs.....
After it's done 1/2 a dozen cycles or so I'll take it for a short run and then let it cool....
I add a step that some others don't use... I've found this seems to work for me and I've never had oil issues with a motor that I've done this to.....
To my knowledge I havn't had micro weld issues with this technique but the motor has been heat cycled quite a few times BEFORE I do this
I'll do this again a little longer and then I take it to about 80kph in top and crack the throttle untill it gets to about 110kph and back it off fully....
This pushes the rings into the bore and the backing off allows oil to be drawn up which cools the ring off and removes the metal you've just scraped off the bore....I cruise for a while and repeat this step a few times...
If it's one of my engines I'll sometimes be very gently and may take a few days to get the initial ring bedding done......I've also run a motor in on the drag strip to try the "Mototune" method and it was down on power compared to what I had in the previous and later setup...
There is also a lot more parts in an engine than just rings and pistons
Here's a copy of the S&S running procedure which is a damn sight better IMO than the Mototune crap
Remember engines are like women...... if ya want a happy one ya gotta run it in right .. and if it's not happy then your life is gonna be miserable
How should I break-in my new S & S engine?
NOTE - S & S Engines require premium gasoline (octane 91 or higher) for best performance. Octane boosting gasoline additives may be necessary with marginal gasoline.
CAUTION - Low octane gasoline and hot weather can cause detonation and extensive engine damage. Never try to power through ignition knock ("ping," "rattle," etc.) by opening throttle.
CAUTION - If engine is run with foreign material in
the oil tank, engine damage will occur. Engine
damage caused by foreign material in the oil tank
is not covered under the S&S warranty.Clean oil tank and oil cooler and flush or
replace oil lines before installing engine in
Engine Break-In Procedure
Note: S&S engines are designed for high performance
and as such are not as tolerant of inadequate break-in
as stock or lower performance engines. Correct breakin
will assure longer engine life and will prevent
unnecessary engine damage. Engine damage caused
by improper break-in is not covered under the S&S
A. Initial start up. Run engine approximately one
minute at 1250-1750 rpm. DO NOT crack
throttle or subject to any loads during this period
as head gaskets are susceptible to failure at
this time. During this time, check to see that oil
pressure is normal, that oil is returning the oil
tank, and that no leaks exist.
B. Shut off engine and thoroughly check for any
leaks or other problems. Let engine cool to the
C. After engine has cooled, start up again and
allow the motor to build some heat. Engine
should be run no longer than three to four
minutes. When the cylinders become warm/
hot to the touch (approximately 150) shut the
motor down and let it cool to room temp. Follow
the same cautions as for the initial start-up, and
continue to watch for problems.
D. Repeat this procedure 3 or 4 times. Each
successive time it should take slightly longer to
warm up and you can increase the temp slightly
each time (+10). You can be more liberal each
time with the rpm, gently vary rpm continuously
from idle up to 2500 rpm in the final cycle. Don?t
be too concerned with final carb settings at this
time because idle speed and mixture cannot
be correctly set until the motor reaches full
operating temperature. The motor should not
reach that temperature during these cycles. Do
not allow engine temperature to become
excessive. After the motor has cooled to room
temperature for the final time you are ready to
start the 1000 mile engine break-in process.
E. The first 50 miles are most critical for new rings
and piston break-in. Engine damage is most
likely to occur during this period. Keep heat
down by not exceeding 2500 rpm. Avoid lugging
the motor, riding in hot weather or in traffic. Vary
the engine speed. Do not lug the engine. We
recommend changing the oil at 50 miles.
F. The next 500 miles should be spent running
engine no faster than 3500 rpm or 60 mph.
Avoid continuous steady speeds, and do not
lug the engine. Vary engine rpm. We
recommend changing the oil again at 500 miles.
CAUTION - Lugging or running engine prematurely at
sustained high rpm may result in damage to pistons and
other engine components. S&S voids it's guarantee if
engine is not broken in properly.
G. For the balance of the first 1000 miles the motor can
be run in a normal but conservative manner. You can
be more liberal with the rpm range and motorcycle
can be operated at normal highway speeds. Avoid
overheating or putting any hard strain on the engine:
no drag racing, dyno runs, excessive speed, trailer
towing or sidecar operation.
H. After 1000 miles, verify carburetor jetting and
adjustment. Change the engine oil. Motorcycle can
now be operated normally.
I. Have Fun!