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Thread: Engine Break In
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post #1 of (permalink) Old 01-16-2006, 09:11 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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