I'm sure a lot of you have heard or read about the theory for breaking in a new engine that if you want great compression, run it HARD on the new engine. I read an article a while back (I'll try to trace it) about a mechanic who ran the test on over 300 engines, all had better compression when ran hard (under certain circumstances) during the break in period than those who follow the manufacturer's guidelines. I remember reading about an AMA superbike GSX-R1000 that had a new motor, put on all the mod's, internals stock from the factory though, dynoed it at 0 miles, did a race, re-dynoed, and ended up having 2 or 3 more wheel hp.

Now, I recently installed new rings on my 250 and when the bike is back up and running, do you think I should break it in easily or just go all out?

 

http://www.mototuneusa.com/break_in_secrets.htm

 

Just remember, you don't want to overheat the cylinder walls during break-in. Give it to her hard, but give her time to cool down in between runs.

 

How I broke in my 7 after overbore/pistons/rings. Warmed her up in the pits, then stayed around 6-7k rpm for the first few laps. rpms of course vary on the track because of downshifting/upshifting. Had a couple of TZ250's that were cutting me off the track at that front straight rpm. Fifth lap, went to 10k rpms to get around the TZ's. Did about 3 or 4 more laps on 10k, before practice was over. From then on after the oil change, it was wfo. Break in was completed within one hr after rebuild.

edit: 1 lap was 1.9 miles

 

I spoken to engine builderswho say break it in hard (sounds a little dirty) and allow time to cool it off. I also had conversations with mechanics who say slow and easy... I don't know.

 

dirty as in redlining the tach? If so, I agree, not my method. Varying the piston/ring load helps seal ie machine the ring and the cylinder to match. If iron linered and the proper ring material are used along with the cross hatch. My case, I opened up the piston to wall clearance to .0025" for less friction. Ran it on the track for 7 yrs without any tear down.

 

Cool, I think I'll try the gradual hard break in method, just gotta map out a nice route around town.

Did you guys notice any difference as far as performance and better compression in the long run?

 

I don't have any problems with heavy oil consumption. That is a very good sign of good compression.

 

I used the Mototune method, and its seems to be doing great after 6500 miles. But you have to do it with a brand new bike in the first 20 miles or so. I think I would have gone crazy trying to keep it under 4000 rpm's. The sweet spot on this bike with the 13-45 and my mods is between 7 and 9 grand.

[sm=gears.gif]

 

Deej don't lie, you run that thing like its going to explode over 6k RPM's. Mine gets run like it will explode under 6000.