..It's a question that is asked on every forum dealing with mopeds to airplanes, autos to lawnmowers, and motorcycles somewhere in between. Here I'll try an answer this question, based on my expertise, Victory motorcycles. I bring up this topic because of a '08 motor we recently tore down for a build. It was severely scored, the reason we'll get to that later, but YOU WILL BE SURPRISED after reading this article and scratch your head thinking about what you've done in the past if your motor isn't hurt all ready.
There will be a few sections to this article, which will cover different engine materials and there required break in procedures along with fueling requirements and maybe if I feel good by the time I get there, oil requirements during break in. This will be a NO HOLDS barred article on facts, however detailed information obtained by Lloyd'z will be left out, if you don't have the stomach for it go read up on the world events and our lousy economy.
Information in this article is NOT related to book material or engineering facts, although it may contain some material found in those areas. This information was obtained in the "Lloyd'z School of Hard Knocks". This is a school I paid for myself and I've attended it for the past 30+ years. Tutorials are one on one, literally! And all though we do have theory's they are experimented on in a hands on environment. Reading for learning purposes is usually held in the "Special office" and those sections usually last about 15-20 minutes every morning. Tests are given and there is a pass/fail qualification rating based on the performance of the "Experiment". Learning comes from mistakes and the occasional "getting it right the first time". This school is NO JOKE! Fail and you're out of a job, income and everything you've worked for. There is NO SUCH THING as, repeating a semester.
So, what's the proper way to break in my engine?I NEVER wanted to get involved with too many of those questions. Everyone (excluding the guys that really know) have their own "idea" based on theory on how a motor should be broken in. We'll start off slow and touch some bases with materials, Victory motor design and some other items you may not have thought about in relationship to engines and useage. A lot of articles point to guys like MOTOMAN, and his break in secrets, I read his article a few years ago and just refreshed myself for this writing. I believe his findings are true and accurate for exactly what he does but there are open ended paragraphs that would suggest to others that his findings apply to everyone and every motor 2 or 4 stroke, as he comments. I know this, if you take a forged piston iron liner motor with the proper clearance and break it in like he suggests you'll be walking home without a running bike. MOTOMAN does have some good points but they're based on sport bike motors with totally different bore / stroke and liquid cooling benefits. For example, if we plug into a good engine builders software, a motor such as a Victory 100 inch configuration of 101mm (3.976") bore and 102mm (4.016") stroke, we will see a 22 hp frictional loss @ 6000 rpm's with this stroke length. By decreasing the stroke 1 full inch from 4.016 to 3.016 we see a 50% reduction in frictional loss to 11 hp at the same 6000 Rpm's. This translates into less friction which equals less heat. With a longer stroke a motor sees more side loading of the piston as a result of the crank and rods angle to the piston bore. This is regardless of whether we increase the bore size to reflect the same cubic inch displacement of left just the stroke decreased. Sport bikes have very short strokes compared to V-Twins make this only 1 of many differences and requirements in how these bikes get "Broken-in".
When you purchase your bike it has been heated and run on the dyno prior to its delivery to the dealership. This is the start of the break in and I've seen it done numerous times on many factory tours. I've paid close attention to the procedure used when they perform the testing that insures every bike runs to the parameters it should. At first I didn't agree with this test in the initial first minute or two of its test, but time and testing have changed that thought. Most will see just a bike and operator performing a task. I see something different based on hundreds of torn apart motors and their damaged parts from one issue or another, flashing through my head like a film projector playing a movie. These images are then fitted with their prospective information and instantly I can see the internals of this running motor and its transformation through its break in.
It doesn't happen because I have a special power, it happens because I know what the internal parts of a motor look like from the time they are installed, then at 5 minutes, 15, 30, 1 hour, 10 miles 30miles 100, 100,000 and so on, time and time again, almost every day I see a different motor apart and mentally categorize it with its time period. An open motor reads just like a book, most of the time the information is right there in front of you and other times it's like watching an episode of CSI, for a period of time you put all the info together and it doesn't make sense until the very end.
When you take delivery of your bike it has already had a start in the break in procedure at the factory, then the tech / dealer preps the bike and takes it for a ride. This may be the second part of its break in.
Lets start off Simple, with Stock Motors. (NiKaSil lined cylinders, Cast pistons, lean conditions). This is what we all start out with, it's the most forgiving & tolerant on break in abuse and it's a good thing. NiKaSil lined motors are very tolerant of wear, heat and abuse. The electro coating NiKaSil is Nickel Silicon Carbide, the second hardest material in the world, is used for its great wear and lubricity characteristics. It's applied and then finish honed with a Diamond stone hone. Why? Because Diamonds are harder then NiKaSil. NiKaSil is normally applied over aluminum because it cuts down considerable the manufacturing expense and it adheres very well in the soft metal. Its properties take heat and abrasion very well and it is the premiere coating for today's 2 & 4 stroke snowmobile engines that see extreme cold to hot fluctuations without seizing. That's why it's used, but it is not impervious to destruction or failure. Cold seizures and lean seizures are two of the biggest culprits that can cause failure to a NiKaSil Bore motor. When either one of these happens the cause is basically the piston expanding faster then the cylinder bore, causing severe heat and abrasion to take place. If there is a .003 (3 thousands) clearance between the piston and cylinder and the piston increases .003 before the cylinder does, the resulting damage will be extreme. Material will melt off the piston and on to the bore surface. Friction increases very quickly. With a Victory engine we have a heavy crank that generates a lot of inertia and tons of torque output. If only one piston starts to seize the other that is still in good shape keeps driving the seizing piston through the stroke causing the damage to worsen. The end result is all most catastrophic if not caught in time with broken pieces everywhere. That's the extreme side of this failure. Most Cast piston NiKaSil bores don't reach this unless you're being extremely aggressive in trying to cause damage. Most damage with this type of set up occurs like this; You start the bike, before completely warming up you rev it high or run it hard down the road, the pistons skirts which take the most heat starts to grow larger and faster then the cylinder can expand. Scuffing starts to occur. As mentioned before it normally doesn't get a chance to grow excessively larger because of it being a cast piston, which is more resilient to growth then forged units. The cylinders in these motors also grow at a very quick rate because they are constructed of aluminum. They also grow out of round because of the material thickness surrounding the bore. There may be 1/2 inch of material on one side of the cylinder and 7/8 of an inch on the other, causing the thicker side to expand slower. This out of round effect can start to scuff pistons and the rings, which want to be round gouge into the lining of the cylinder creating what looks like a smeared coating of the NiKaSil. This is common on a lot of motors we disassemble and the cause of the 08 mentioned above. The effects of this smearing or scuffing are most commonly done in several areas around the inside of the cylinder with some spots being heavier than others. How do we stop this from occurring? The answer is my first rule of break-in:
#1: Completely warm the motor and oil temps before running hard, never start a motor and rev it cold.
I‘ve seen this happen when guys want to show off the pipes or motor build. I cringe every time I see someone doing this.
What is the recommended break in procedure for these types of motors on the street? In my opinion the break in of these motors is more concentrated on the fact that they'll take allot of abuse but hardly any misuse. Properly bringing this type of motor and its oil up to operating temperature before any hard accelerating or high revving is an absolute must. I like to see the motor hot to the touch prior to riding for at least the first few hundred miles, after that warm to the touch is comfort enough for me. Petroleum based oil is best suited for break in purposes and we use Victory semi-synthitic oil for our builds. I recommend changing the oil & filter after the first 100-500 miles. Specific break in oils that contain high Zink levels such as the Joe Gibbs BR oils aren't required for this application of NiKaSil and roller lifter motors.
Which brings me to my next 2 rules:
#2: Vary motor revs and do decompression roll-on's during break-in.
#3: Always use the correct oil rating and weight for the engine requirements.
It may all sound hard but don't worry if you can't follow this to a tee, these motor configurations are forgiving. One item to keep in mind for those that live in colder climates such as I is that the oil temps will take 3-4 times longer to rise in temperature then the cylinders or heads. This is important because the warmer oil will properly lubricate and protect the needed items during the critical warm up process when most just want to hop in and go. We've all seen it, a group of bikes parked outside of a bar or restaurant for a few hours, the owners come out fire up, without delay they take off wide open down the road to show off their stuff. What they don't realize is that the only thing they show is more signs of wear when they engine guy gets a hold of the motor from a shorter then expected life. Hence:
#4: Pulling steep grades with a NiKaSil motor helps the heating process but should be limited to no more than a couple miles of grade with a coasting or decompression down the other side.
Using my Dyno for the Break-inOccasionally we need to build a motor and then get dyno readings of it before delivering it to our customer. My recommended Dyno break-in for a NiKaSil motor with Cast pistons is first taking a cranking compression reading before even firing the bike then after a proper warm up, bring it slowly through the rpms and gears until I feel the oil temps are up, I'll make five to six 4th-5th gear runs while my cooling fans are on, allowing the motor to come down under it's own power after every run and viewing the power after each run. The motor may feel hot when you first do this but we want to make sure and it should feel to the touch very hot when you rest your hand on the cylinder. I'll only run the first few up to the 3800-4000 rpm range but that's usually enough to see the difference in how the motor is acting and seating in. Usually the motor at this point on the dyno is maxing the power and we normally won't see the power levels raise any higher under the same hot condition. The air fuel from the first pull on should be checked and adjusted to the proper ratio to avoid other issues related to an overly lean or rich condition. I'll normally let the motor cool under the fans for a 10-15 minute time while checking for oil leaks and recording the cylinder and head temps for our database. After the cool down, I fire it up for another warm up period and back to building the fuel map. While building the fuel map I'll start at the lower rpms first and then progressively move up to the higher rpms but not until I feel the bike has hard enough run time on it, usually 25-30 minutes. After the dyno treatment it's back in the shop for another compression check but this time we do it warm, we also do a visual check with a digital vision scope to look for any signs out of the ordinary. This data is recorded for each motor build and reviewed to other builds of similar compression and cam timing.
There are other parts of the motor that also need to be broken-in or, for that matter, carefully heated prior to any riding. One of these is the cams and carriers. We've seen a significant amount of carriers that are scored, most of this occurring as a result of not properly warming up the motor prior to riding. If we could video these components as they go through there warming cycles you would be instantly aware of how needed a proper warm up cycle is. The clearance for cams and carrier is best at operating temps since the carrier is made of aluminum and the cam is billet or ductile iron which grows very little compared to the ferrous metal. Cam carrier scoring is a common scene in these motors and is more noticeable on bikes that have impatient owners.
#5: Never free-rev a cold motor! Never! Even after the break-in period. Hey, you in the black tshirt! Never!
---OK, one more Disclaimer---
These are the procedures we at Lloydz Motorworks use to break in a NiKaSil/Cast piston motor. They are NOT the same for motors with forged or iron liners. Using these techniques during the break in of those motors will surly leave you with a damaged build. The next article will focus on the break in of those types of builds and why they differ.
Stay Tuned! (pun definitely intended)