The "mysticism"of engine break in

[guydoc77]

Since the issue of engine break in continues to come up, I thought I'd start this thread to see what people understand or don't understand about engine break in. Some of the notions out there continue to baffle me. "Go put 1000 miles on it then we'll tune it." "Should I break it in on the dyno?"
What is break in actually?
How long does it actually take?
Why wouldn't you want to "break in" on the dyno?

Let's attempt to remove the apparent black magic some seem to associate with engine break in.

[K4FXD]

I've been breaking them in the same since I started. Assuming roller cam, warm them up, let cool, warm up again, hit the drag strip. Opps, that was our race car motors.

Bike motor, Warm up, let cool, warm up again and hit the road. Change oil and ride.

I figure if its going to blow let it blow right away.

[kd]

Here's a good read to start the conversation. For the reasons stated in this article, it is also my preferred method if we are counting votes. That comes with the provision that the tune is absolutely correct. An example would be for a rebuild of a stellar tuned engine or an AFR and timing check before rolling down the road.

While I was typing K4FXD responded and (without hearing the actual details of his procedure) I somewhat agree with that approach. In fact I just yesterday fired my hopped up 120 motor and after a quick Moto tune run through I am riding it hard. 

[bigfoot5x]

We have bought all of our Harley's new except one. My thinking is that if the manufacturer wants to have a good reputation, they will  determine what is best for their product. I always break in following guidelines in the owners manual for that reason. I do regular maintenance and get lots of miles out of all my vehicles. Nothing really special.

[Deye76]

IMO breaking in on the dyno takes all the "mystery" out of it.

[kd]

IMO breaking in on the dyno takes all the "mystery" out of it.

I agree, "when possible it would be the best approach). A dyno is not always available or an option.

[jmorton10]

I can tell you one thing, if a bike is bought brand new from a dealer there is no reason to baby it.

I worked at a dealer for a few years & when we test drove new bikes we made sure the rev limiter worked correctly on every test ride LOL.

~John

[prodrag1320]

IMO breaking in on the dyno takes all the "mystery" out of it.

as long as its done by a tuner that knows how to properly break a motor in on a dyno

[TXChop]

I can tell you one thing, if a bike is bought brand new from a dealer there is no reason to baby it.

I worked at a dealer for a few years & when we test drove new bikes we made sure the rev limiter worked correctly on every test ride LOL.

~John

Not to mention if a bike wasnt sold for a while it was started and driven across the parking lot in the morning and shut off.
And then the same at night. So some bike were run for about 1 minute a day for months if not sold right away.

[Deye76]

IMO breaking in on the dyno takes all the "mystery" out of it.

as long as its done by a tuner that knows how to properly break a motor in on a dyno

Agreed, I assumed anyone on this site knew who the good tuner/operators are.

[Trouble]

Fifty miles of regular riding to determine how everything sounds, tune, etc.,  then start throwing some heat at it to seat the rings. Done this way, more power, less oil loss, lots of smiles. JMHO

[PoorUB]

Fifty miles of regular riding to determine how everything sounds, tune, etc.,  then start throwing some heat at it to seat the rings. Done this way, more power, less oil loss, lots of smiles. JMHO

Fifty?? More like ten miles! By fifty miles it's too late!

I don't ride regularly the first few miles. I run it through the gears near full throttle but never over 4,000 RPM, do it over several times. Around fifty miles it's done, ride it like you stole it!

[guydoc77]

To me "break in" is the seating of the rings in the bore.
And I agree, it takes only minutes to do.

Things that WILL ruin the break in are not warming the new motor sufficiently prior to first operation, but, most importantly, running it with literally no idea what the air fuel ratio is and with too much or too little timing or extremely rich or lean AFR.

The perpetuated notion that some sort of "starter" map is "safe" is what baffles me. If good ring/bore seal can be established in minutes, doesn't it also follow that it can also be permanently harmed too some degree if AFR and timing are way off?

To me that is the risk involved in "starter map" break in.
These are the builds with all the correct parts that never run like expected.
I have personally seen AF ratios in the high teens when "starter map" builds finally get on the dyno.
I have listened to new motors ping and detonate as the owner "breaks them in" for 1000 miles prior to dyno.
I have seen canned map motors shell out with limited miles, never having actually been properly tuned.

I get the lure and seemingly cost effectiveness of self tuning with the stock EFI narrow bands. I get that.
If the build is not extremely close to the build of whatever canned map was developed by whomever, what sort of damage is done to ring seal during the self tuning? Can we be certain of the AFR or timing while the tuning device "learns"? And, if there are parts of the map that are close, what does the adaptive fueling and timing do to those areas of the map while the tuning device and ECU compete to correct the way off parts of the map?

These are the thoughts and questions I have on this topic.

[smoserx1]

IMO this subject is way over analyzed, much like an oil discussion.  When I bought my one and only FLHT (which I still ride regularly) nobody said anything to me about break in.  My maiden voyage was about 70 miles home, I would shift at about 3500 RPM cause it felt about right.  When I got home I read the owners manual and worried that I caused damage by going over 2500 RPM the first 50 miles.  Actually the recommended gear/RPM recommendations in the owners manual seem like lugging.  Anyway the engine did fine.  It went 16 years and 179000 miles on the original top end, and even survived a cam bearing failure.  It did gradually use more and more oil, but in the end it was still no more than a quart per 2000 miles or so.  Then one of the base o-rings started leaking.

Two years ago I fixed the leak with SE 95 inch cylinders, flat tops and low mileage stock heads from ebay.  Did it all myself.  I remember thinking the stuff I removed looked pretty good (and was certainly running fine).  I did the "MotoMan" break in this time.  A warm up then 4 or 5 5000 RPM shifts the first couple of miles with high RPM throttle chops (yes that is radical as hell).  Two years later and 11000 more miles all seems well.

Just ride your bike normally and it should break in fine.

[bigfoot5x]

Every Harley is started and run on rollers in the factory before shipping as the final test. My dealer runs each bike on a 7 mile test loop and I don't know how they ride the bike but I would hope that the mechanic is treating somebody's new ride with some respect and kid gloves. I still maintain that Harley has established a break in pattern that they feel is best for the engine they designed. They have to stand behind the product. Not us.

[Hossamania]

I was assuming the OP was talking about a custom or aftermarket build on a motor. Not a factory new bike and motor. That is what I was basing my input on.

[harleytoprock]

It's amazing that there is such extreme recommended break in procedure differences. Where one side says redline it from the get go, others recommend mild break in's like S&S. S&S recommends staying under 2500 rpm for first 500 miles and then under 3500rpm for the next 500 miles. No drag racing, excessive speed, dyno runs, trailer towing or sidecar operation for the first 1000 miles. So if you dyno your new S&S motor with less then a 1000 miles, will that void their warranty?

[K4FXD]

Maybe I'll figure out how to quote people someday.

The method S&S stated, is how we used to break in motors with coarse hone jobs and chrome or cast rings. Outdated technology. It used to take 500 to 1000 miles to completely seat rings.

Today's hones are much finer and the ring material is different. The rings are 95% seated after 25 miles, give or take.

Break in however you like.

For me with a non stock FI motor I would break in on a dyno, but I sure as hell wouldn't baby it once the afr's were sorted out.

[hbkeith]

I ride with constant rolling the throttle low to higher RPM for 50 miles , then ride it normal , never a problem

[1FSTRK]

One good thing about the break them in fast guys is they post the best info on how to modify your breathers to outside the air cleaner and where to mount the catch cans.

[FLHRI_2004]

One of the big no-no's for break in is not to lug the engine.  Well, you should never lug it, but you certainly don't want to lug it while breaking it in.

[Don D]

So what about drag bikes? They rely on low leak numbers for top performance. What do the racers do for instant success?

[K4FXD]

Not sure about the racing bikes, but with our race car motors, BB Chevy's, we warm them up, shut down, fix anything that needs attention, warm up again and run a full pass down the strip. Or if available do the same thing on a dyno.

Leakdown runs around 5% avg. Most are less.

My Twin cam motor was broke in the same way. (I didn't run it down a drag strip but I hit the road and gave it full throttle through all gears) I don't have any oil in my breather.
I might do a leak down test just for giggles.

[Don D]

EFI is a game changer however and fuel and timing by program VS demand is very different.

[K4FXD]

FI, unless a stock re-fresh, yes a dyno is almost a must. However once the map is sorted, LOAD IT. Do a couple of full pulls and let the dyno slow the thing, pull high vacuum.

Anyway that is how I do it.

YMMV