Brake in?

[ocotilloboy]

I here alot of different ways of braking in quads but what is a good brake in procedure.

[GPracer2500]

I notice your loaded with 07's (nice!) so I assume you're talking about breaking in a stock engine. Stock piston's are cast so there is no reason to "heat cycle" like there would be with a forged piston (most aftermarket pistons are forged). Probably the most important thing is to very the RPMs as much as possible, use engine breaking on deceleration, and try to keep a load on the engine. Basically, shoot for bursts of acceleration (that's the loading) and then deceleration using engine breaking. Keep the RPMs moderate at first and then slowly build to higher and higher RPMs. Occasional WOT is ok during acceleration (good even) but avoid zinging the engine to redline in the beginning.

The point to all of that is to help ensure proper ring seal. That's most of what beak-in is all about--ring seal. With a forged piston there can be an additional need to heat cycle the piston for internal stress-relieving purposes. Note that heat cycling for stress-relief is generally not the same as heat treating which is done by the manufacture to harden metals to their desired specification. The loading part is important because high loads and WOT operation create high cylinder pressures. These high pressures are necessary because it's pressure in the cylinder that forces the rings against the cylinder walls.

that's my $0.02

[krt400ex]

Originally posted by GPracer2500
I notice your loaded with 07's (nice!) so I assume you're talking about breaking in a stock engine. Stock piston's are cast so there is no reason to "heat cycle" like there would be with a forged piston (most aftermarket pistons are forged). Probably the most important thing is to very the RPMs as much as possible, use engine breaking on deceleration, and try to keep a load on the engine. Basically, shoot for bursts of acceleration (that's the loading) and then deceleration using engine breaking. Keep the RPMs moderate at first and then slowly build to higher and higher RPMs. Occasional WOT is ok during acceleration (good even) but avoid zinging the engine to redline in the beginning.

The point to all of that is to help ensure proper ring seal. That's most of what beak-in is all about--ring seal. With a forged piston there can be an additional need to heat cycle the piston for internal stress-relieving purposes. Note that heat cycling for stress-relief is generally not the same as heat treating which is done by the manufacture to harden metals to their desired specification. The loading part is important because high loads and WOT operation create high cylinder pressures. These high pressures are necessary because it's pressure in the cylinder that forces the rings against the cylinder walls.

that's my $0.02

what is heat cycling?

[johnsls]

I'm no pro at this but what GPracer stated seems to sound right to me.

When I had my JE Piston installed we(Steve) set the idle at about 3000rpms and ran a mixer of race fuel and high octane gas for about 20 minutes,, shut it down , changed the oil and WHOLA,, all done and ready to ride.

my 2¢

[GPracer2500]

Originally posted by krt400ex
what is heat cycling?

Heat cycling is process of getting the engine up to tempurature and then letting it cool ALL THE WAY back down. This is done several times. A cast piston doesn't need this, but a forged piston might. I say "might" because it somewhat depends on the exact manufacturing processes performed by the manufacture of the piston. For example, Wiseco mentions that they "heat-treat" their pistons as part of the finishing process. It's not clear to me at this time whether that includes anything designed to stress-relieve the metal or not (I'm working on an answer to that). The term "heat-treat" is most often concerned with the hardening of a metal, but not necessarily with stress-relief.

Stress-relief is important in forged metals. Forging is a process of manufacturing in which a chunk of heated metal is literally beaten into the desired shape. The common alternative is casting which is when molten metal is pored into a mold to create the desired shape. Forging is stronger (mostly) because it creates a more dense final product. But in the process of forging the grain of the metal gets "confused" and this causes spots of internal stress. Periods of heating and cooling can relieve those stresses and leave you with a stress-free piston. Cast pistons don't require stress-relief because their grain struction is uniform--no internal stress is created during the manufactuing process.

The heat cycling of a piston usually involves warming up the engine and as soon as it's up to temp let it cool off completely. A couple of cycles is the common recomendation. I'm a believer in taking all resonable steps to ensure proper ring seal, so I choose to actually ride a bike/quad during the heat cycling process but many choose to do at least the first warm-up in the garage. Don't misconstrue that to mean that I don't warm up and engine before riding it--I do. But I choose to put ever increasing loads on the engine as soon as I feel there is enough heat in the piston/cylinder to prevent a cold-seizure.

[krt400ex]

Originally posted by GPracer2500
Heat cycling is process of getting the engine up to tempurature and then letting it cool ALL THE WAY back down. This is done several times. A cast piston doesn't need this, but a forged piston might. I say "might" because it somewhat depends on the exact manufacturing processes performed by the manufacture of the piston. For example, Wiseco mentions that they "heat-treat" their pistons as part of the finishing process. It's not clear to me at this time whether that includes anything designed to stress-relieve the metal or not (I'm working on an answer to that). The term "heat-treat" is most often concerned with the hardening of a metal, but not necessarily with stress-relief.

Stress-relief is important in forged metals. Forging is a process of manufacturing in which a chunk of heated metal is literally beaten into the desired shape. The common alternative is casting which is when molten metal is pored into a mold to create the desired shape. Forging is stronger (mostly) because it creates a more dense final product. But in the process of forging the grain of the metal gets "confused" and this causes spots of internal stress. Periods of heating and cooling can relieve those stresses and leave you with a stress-free piston. Cast pistons don't require stress-relief because their grain struction is uniform--no internal stress is created during the manufactuing process.

The heat cycling of a piston usually involves warming up the engine and as soon as it's up to temp let it cool off completely. A couple of cycles is the common recomendation. I'm a believer in taking all resonable steps to ensure proper ring seal, so I choose to actually ride a bike/quad during the heat cycling process but many choose to do at least the first warm-up in the garage. Don't misconstrue that to mean that I don't warm up and engine before riding it--I do. But I choose to put ever increasing loads on the engine as soon as I feel there is enough heat in the piston/cylinder to prevent a cold-seizure.

thank u. that was very thorough. i never knew that before