Engine Break In - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 2 (permalink) Old 01-16-2006, 10:11 PM Thread Starter
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Engine Break In

Break In Your Engine For More Power & Less Wear !

One of the most critical parts of the engine building process is the break in !! No matter how well an engine is assembled, it's final power output is up to you !! Although the example here is a Suzuki, these principles apply to all 4 stroke engines; Street or Race Motorcycles, Cars, Airplanes & yes ... even Lawn Mowers !! ( regardless of brand, cooling type, or number of cylinders. ) The same break in techniques also apply to all traditional steel cylinders and Nikasil (GSXR) & ceramic composite cylinders like Yamaha uses on it's R6-7-1.
What's the Best Way to Break in a New Engine ??

The Short Answer: Run it Hard ! Why ?? The piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber. If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall....

How can that seal 3,000 + lbs. of combustion pressure on the way down ?? Of course it can't. How Do Rings Seal Against 3000+ lbs of Combustion Pressure ?? From the actual gas pressure itself !! The pressure takes the path of least resistance, which means it passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough (open that throttle man !!!), then the entire ring will make contact with the cylinder surface, and it will wear perfectly into the right shape.

The Problem With "Easy Break In" ... The rough crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly "use up" the roughness, regardless of how hard the engine is run. There's a very small window of opportunity to get the rings to seal really well ... only about 20 miles !! If the rings aren't forced against the walls, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again. Fortunately, most new sportbike owners can't resist the urge to "open it up" once or twice, which is why more engines don't have this problem !! An additional factor that you may not have realized, is that the person at the dealership who set up your bike probably blasted your brand new bike pretty hard on the "test run". So, without realizing it, that adrenaline crazed set - up mechanic actually did you a huge favor !!

Here's How To Do It: Alan "Schmidtastic" Schmidt's 2001 GSXR 750 cylinders & pistons after being broken in on a dyno. The ring seal was phenomenal !! This AMA Supersport bike was so fast at Daytona 2001 that Alan could easily stay in the draft of Eric Bostrom's Factory Kawasaki ZX7 Superbike all the way around the banking ! ( Think about that $250,000 bike being chased by a little 'ol supersport bike at one of the highest HP tracks in the USA !! ) On a Dyno: Cool Down is important since the cooling fan at most dyno facilities is too small. Use these cool down tips whenever you use a dyno. Warm the engine up completely ... then, using 4th gear: Do Three 1/2 Throttle runs from 40% - 60% of your bike's max rpm Let it Cool Down For About 15 Minutes Do Three 3/4 Throttle runs from 40% - 80% of your bike's max rpm Let it Cool Down For About 15 Minutes Do Three Full Throttle runs from 30% - 100% of your bike's max rpm Let it Cool Down For About 15 Minutes Go For It !!

On the Street: Warm the engine up completely: Because of the wind resistance, you don't need to use higher gears like you would on a dyno. The main thing is to load the engine by using the above recommended throttle settings in 1st, 2nd and 3rd gear. Realistically, you won't be able to do the full throttle runs even in 2nd gear on most bikes without exceeding 65 mph / 104 kph !! The best method is to alternate between short bursts of acceleration and deceleration. You don't have to go over 65 mph / 104 kph to do this, just make sure that you're not being followed closely by another bike or car when you decelerate ! The biggest problem with breaking your engine in on the street (besides police) is if you ride the bike on the freeway (too little throttle = not enough pressure on the rings) or if you get stuck in slow city traffic. For the first 200 miles or so, get out into the country where you can vary the speed more and run it through the gears ! Be Safe On The Street ! Watch your speed ! When you're not used to the handling of a new bike, you should accelerate only on the straightaways, then slow down extra early for the turns. Remember that both hard acceleration and hard engine braking (deceleration) are equally important during the break in process. On the Racetrack: Warm the engine up completely, then: Do one easy lap to warm up your tires, following the above maximum rpm percentage guidelines. Pit, turn off the bike & check for leaks or any safety problems. Take a normal 15 minute practice session and check the water temperature occasionally. Go For It !!

NOTE: If you use a dyno with a brake, it's critical during break - in that you allow the bike to decelerate fully on it's own. The engine vacuum created during deceleration sucks the excess oil and metal off the cylinder walls to keep the rings from wearing too much. That's why a new engine "smokes" on decel. If you're doing it right, you'll notice the smoke goes away after about 7-8 runs. If you use the dyno brake the rings will gum up with oil-metal-nikasil.

Yeah - But ... the owner's manual says to break it in easy ... Notice that this technique isn't "beating" on the engine, but rather taking a purposeful, methodical approach to sealing the rings. The logic to this method is sound. However, some will have a hard time with this approach, since it seems to "go against the grain". The argument for an easy break - in is usually: "that's what the manual says" .... Or more specifically: "there may be tight parts in the engine and it might do damage or even seize if it's run hard." Consider this: If there is something wrong with the engine clearances from the factory you'll find out about it soon enough no matter how easy or hard you run the bike. As long as the engine is fully brought up to temperature before it's run hard, you should never have a problem. If there are any parts that are tight enough to cause seizure, no amount of running will loosen them up and fix the problem ! The real reason ??? So why do all the owner's manuals say to take it easy for 3,000 miles ??? Because, if there is a problem with the assembly from the factory, the manufacturers have to cover their A$$...
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post #2 of 2 (permalink) Old 01-16-2006, 10:15 PM Thread Starter
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Q: What is the most common cause of engine problems ??? A: Failure to: Warm the engine up completely before running it hard !!!
Q: What is the second most common cause of engine problems ???
A: An easy break in !!! Because, when the rings don't seal well, the blow-by gasses contaminate the oil with acids and other harmful exhaust by-products !! Ironically, an "easy break in" is not at all what it seems. By trying to "protect" the engine, the exact opposite happens, as leaky rings continue to contaminate your engine oil for the rest of the life of your bike !!

A Picture's Worth A Thousand Words... These Honda F3 pistons show the difference. The one on the right was broken in as per MotoMan's instructions. After a full season of hard racing: Perfect ring seal, no scuffing, lots of trophies !! Both came out of race bikes, and their owners used the same type of fuel and oil. The only difference was the break in method they used... The one on the right was broken in as per MotoMan's instructions. The one on the left was broken in exactly according to the owner's manual. The resulting leaky rings have allowed pressure to "blow by" down into the crankcase on acceleration, and oil to "suck-up" into the combustion chamber on deceleration. Needless to say, this bike was slow !! It's up to you: The loss in power from improper break in and the resulting poor ring seal can be anywhere from 2% - 10% !!

Q: What's the third most common cause of engine problems ???
A: Not changing the oil soon enough after the engine is first run !! Change Your Oil Right Away !! The best thing you can do for your engine is to change your oil and filter after the first 20 miles. Most of the wearing in process happens immediately, creating a lot of metal in the oil. Plus, the amount of leftover machining chips and other crud left behind in the manufacturing process is simply amazing !!

You want to flush that stuff out before it gets recycled and embedded in the transmission gears, and oil pump etc... 3 more words on break- in: NO SYNTHETIC OIL !! Use Valvoline, Halvoline, or similar 10 w 40 Petroleum Car Oil for at least 2 full days of hard racing or 1,500 miles of street riding. After that use your favorite brand of oil.

Q: If break- in happens so quickly, why do you recommend using break- in oil for 1500 miles ??
A: Because while about 80% of the ring sealing takes place in the first hour of running the engine, the last 20% of the process takes a longer time. Street riding isn't a controlled environment, so most of the mileage may not be in "ring loading mode". Synthetic oil is so slippery that it actually "arrests" the break in process. I've had a few customers who switched to synthetic oil too soon, and the rings never sealed properly no matter how hard they rode. Taking a new engine apart to re - ring it is the last thing anyone wants to do, so I recommend a lot of mileage before switching to synthetic. It's really a "better safe than sorry" situation.

Q: What about the transmission gears, don't they break - in ??
A: Yes they do !! The faces of the gears have a slight roughness to them. After a while the roughness goes away and the gears have a more polished look. There must be an additional amount of friction, but I've never seen a new bike run noticeably hotter because of it. So while the gears do "break in" there's no reason for adhering to any special rpm limits out of worries about gear or heat damage.

Q: What about the main and rod bearings, don't they break - in ??
A: Actually, the operation of plain bearings doesn't involve metal to metal contact !! The shiny spots on used bearings are caused from their contact with the crankshaft journals during start up after the engine has been sitting a while, and the excess oil has drained off. This is the main reason for not revving up the engine when it's started. The subject of plain bearings is one of the most mysterious aspects of engines, and will be covered in a future issue of Power News. In it I'll reveal more information that fully explains the non-contact phenomenon.

Q: Why change the oil at 20 miles ?? Doesn't the oil pick up screen catch the aluminum chips ???
A: It's true that the screen stops the big pieces, but the transmission gears and their ball bearings are unprotected by the filtration system !! After the transmission gears chew the loose aluminum bits into paste, they do get past the screen. A close examination of a new engine will reveal lots of aluminum deposits on steel parts. This aluminum coats and tightens up the clearances of the parts, which creates a loss of power. Most of the time I spend "blueprinting" an engine is actually inspecting every part and "de-aluminizing" them !!

Q: What about the oil filter, doesn't it catch the metal paste ??
A: When soft metals are loose in the engine, they get pulverized by the gears and oil pump, and the super fine particles do get past the entire filtration system. These particles are too small to "scratch" the bearings, but they do something much worse ... they coat them, and take up the oil clearance !! Tight oil clearances cause a power loss, and really tight clearances cause seizure. I prefer to remove the oil pan and clean the aluminum bits out of a new engine out that way, but a $20 oil change is an easy and inexpensive way to flush the initial particles that come loose in the first miles.
Q: What about motorcycle v.s. car oils ???
A: This is a topic all by itself !! It will be covered in a future issue of Power News.

Q: Will this break - in method cause my engine to wear out faster ???
A: No, in fact I always opt for reliability before power !! The irony here is that by following these instructions, you'll find that your oil is cleaner, the engine will rev quicker from not being "aluminized", and you'll have better torque and power across the power range. Reliability and Power are 100% connected !! I hope this page will help you to make an informed decision about how to break in your new engine. If you have any more questions, e-mail me !! Sincerely, Pat McGivern ~MotoMan
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