Understanding Exhaust
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ClaytonFirth
Reardo
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Did this help you understand the exhaust?
Understanding Exhaust
Reardo Thu 17 Mar 2011, 10:12 pm
Understanding Exhaust:
The How & Why
No exhaust system is ideal for all applications. Depending on their design and purpose,
all exhaust systems compromise something to achieve something else. Before performing
exhaust changes or modifications to increase performance, it is critical to determine what
kind of performance you want.
* Do you want the best possible low-end and mid-range power or maximum top-end
power?
* Will you be using an aftermarket cam with different lift, duration, timing and overlap?
* Have you investigated the relationship between torque (force) and horsepower (amount
of work within time)?
* Do you want a cosmetic exhaust system or a performance exhaust system?
Without careful thought about these variables, an exhaust system can yield very
disappointing results. On the other hand, a properly designed and tuned exhaust system
that is well-matched to the engine can provide outstanding power gains.
The distinction between "maximum power" and "maximum performance" is significant
beyond general discussion. Realistically, one exhaust system may not produce both
maximum power and maximum performance. For a motorcycle to cover "X" distance as
quickly as possible, it is not the highest peak power generated by the engine that is most
critical. It is the highest average power generated across the distance that typically
produces the quickest time. When comparing two horsepower curves on a dynamometer
chart (assuming other factors remain constant), the curve containing the greatest average
power is the one that will typically cover the distance in the least time and that curve
may, or may not, contain the highest possible peak power.
In the strictest technical sense, an exhaust system cannot produce more power on its own.
The potential power of an engine is determined by the proper amount of fuel available for
combustion. However, the efficiency of combustion and engine pumping processes is
profoundly influenced by the exhaust system. A properly designed exhaust system can
reduce engine pumping losses. Therefore, the design objective for a high performance
exhaust is (or should be) to reduce engine-pumping losses, and by so doing, increase
volumetric efficiency. The net result of reduced pumping losses is more power available
to move the motorcycle. As volumetric efficiency increases, potential fuel mileage also
increases because less throttle opening is required to move the motorcycle at the same
velocity.
Much controversy (and apparent confusion) surrounds the issue of exhaust "back-
pressure". Many performance-minded people who are otherwise knowledgeable still
cling tenaciously to the old school concept.... "You need more back-pressure for better
performance."
For virtually all high performance purposes, backpressure in an exhaust system increases
engine-pumping losses and decreases available engine power. It is true that some engines
are mechanically tuned to "X" amount of backpressure and can show a loss of low-end
torque when that backpressure is reduced. It is also true that the same engine that lost
low-end torque with reduced back-pressure can be mechanically re-tuned to show an
increase of low-end torque with the same reduction of back-pressure. More importantly,
maximum mid-to-high RPM power will be achieved with the lowest possible
backpressure. Period!
The objective of most engine modifications is to maximize the proper air and fuel flow
into, and exhaust flow out of the engine. The inflow of an air/fuel mixture is a separate
issue, but it is directly influenced by exhaust flow, particularly during valve overlap
(when both valves are open for "X" degrees of crankshaft rotation). Gasoline requires
oxygen to burn. By volume, dry, ambient air at sea level contains about 21% oxygen,
78% Nitrogen and trace amounts of Argon, CO2 and other gases. Since oxygen is only
about 1/5 of air’s volume, an engine must intake 5 times more air than oxygen to get the
oxygen it needs to support the combustion of fuel. If we introduce an oxygen-bearing
additive such as nitrous oxide, or use an oxygen-bearing fuel such as nitromethane, we
can make much more power from the same displacement because both additives bring
more oxygen to the combustion chamber to support the combustion of more fuel. If we
add a supercharger or turbocharger, we get more power for the same reason…. more
oxygen is forced into the combustion chamber.
Theoretically, in a normally aspirated state of tune without fuel or oxygen-rich additives,
an engine’s maximum power potential is directly proportional with the volume of air it
flows. This means that an engine of 80 cubic inches has the same maximum power
potential as an engine of 100 cubic inches, if they both flow the same volume of air. In
this example, the powerband characteristics of the two engines will be quite different but
the peak attainable power is essentially the same.
Flow Volume & Flow Velocity
One of the biggest issues with exhaust systems, is the relationship between gas flow
volume and gas flow velocity (which also applies to the intake track). An engine needs
the highest flow velocity possible for quick throttle response and torque throughout the
low-to-mid range portion of the power band. The same engine also needs the highest flow
volume possible throughout the mid-to-high range portion of the powerband for
maximum performance. This is where a fundamental conflict arises. For "X" amount of
exhaust pressure at an exhaust valve, a smaller diameter exhaust pipe will provide higher
flow velocity than a larger diameter pipe. Unfortunately, the laws of physics will not
allow that same small diameter pipe to flow sufficient volume to realize maximum
possible power at higher RPM. If we install a larger diameter pipe, we will have enough
flow volume for maximum power at mid-to-high RPM, but the flow velocity will
decrease and low-to-mid range throttle response and torque will suffer. This is the
primary paradox of exhaust flow dynamics and the solution is usually a design
compromise that produces an acceptable amount of throttle response, torque and
horsepower across the entire powerband.
A very common mistake made by some performance people is the selection of an exhaust
system with pipes that are too large in diameter for their engine's state of tune. Bigger is
not necessarily better and is often worse.
Equal Length Exhaust
The effectiveness of equal length exhaust is widely debated.
Assuming that an exhaust system is otherwise properly designed, equal length pipes offer
some benefits that are not present with unequal length pipes. These benefits are smoother
engine operation, tuning simplicity and increased low-to-mid range torque.
If the pipes are not equal length, both inertial scavenging and wave scavenging will vary
among engine cylinders, often dramatically. This, in turn, causes different tuning
requirements for different cylinders. These variations affect air/fuel mixtures and timing
requirements, and can make it very difficult to achieve optimal tuning. Equal length pipes
eliminate these exhaust-induced difficulties. "Tuning", in the context used here, does not
mean installing new sparkplugs and an air filter. It means configuring a combination of
mechanical components to maximum efficiency for a specific purpose and it can not be
overemphasized that such tuning is the path to superior performance with a combination
of parts that must work together in a complimentary manner.
In an exhaust system that is properly designed for it’s application, equal length pipes are
generally more efficient. The lengths of both the primary and main section of pipes
strongly influence the location of the torque peak(s) within the powerband. In street and
track performance engines with longer pipes typically produce more low-to-mid range
torque than shorter pipes and it is torque that moves a motorcycle. The question is...
Where in the powerband do you want to maximize the torque?
* Longer pipes tend to increase power below the engine’s torque peak and shorter pipes
tend to increase power above the torque peak.
* Large diameter pipes tend to limit low-range power and increase high range power.
* Small diameter pipes tend to increase low-range power and to some degree limit high-
range power.
* "Balance" or "equalizer" chambers between the exhaust pipes tend to flatten the torque
peak(s) and widen the powerband.
Among the more astute and responsible exhaust builders, it is more-or-less understood
that pipe length variations should not exceed 1" to be considered equal. Even this
standard can result in a 2" difference if one pipe is an inch short and another pipe is an
inch long.
Exhaust Scavenging and Energy Waves
Inertial scavenging and wave scavenging are different phenomena but both impact
exhaust system efficiency and affect one another. Scavenging is simply gas extraction.
These two scavenging effects are directly influenced by pipe diameter, length, shape and
the thermal properties of the pipe material (stainless, mild steel, thermal coatings, etc.).
When the exhaust valve opens, two things immediately happen. An energy wave, or
pulse, is created from the rapidly expanding combustion gases. The wave enters the
exhaust pipe traveling outward at a nominal speed of 1,300 - 1,700 feet per second (this
speed varies depending on engine design, modifications, etc., and is therefore stated as a
"nominal" velocity). This wave is pure energy, similar to a shock wave from an
explosion. Simultaneous with the energy wave, the spent combustion gases also enter the
exhaust pipe and travel outward more slowly at 150 - 300 feet per second nominal
(maximum power is usually made with gas velocities between 240 and 300 feet per
second). Since the energy wave is moving about 5 times faster than the exhaust gases, it
will get where it is going faster than the gases. When the outbound energy wave
encounters a lower pressure area such as a second or larger diameter section of pipe, the
muffler or the ambient atmosphere, a reversion wave (a reversed or mirrored wave) is
reflected back toward the exhaust valve without significant loss of velocity.
The reversion wave moves back toward the exhaust valve on a collision course with the
exiting gases whereupon they pass through one another, with some energy loss and
turbulence, and continue in their respective directions. What happens when that reversion
wave arrives at the exhaust valve depends on whether the valve is still open or closed.
This is a critical moment in the exhaust cycle because the reversion wave can be
beneficial or detrimental to exhaust flow, depending upon its arrival time at the exhaust
valve. If the exhaust valve is closed when the reversion wave arrives, the wave is again
reflected toward the exhaust outlet and eventually dissipates its energy in this back and
forth motion. If the exhaust valve is open when the wave arrives, its effect upon exhaust
gas flow depends on which part of the wave is hitting the open exhaust valve.
A wave is comprised of two alternating and opposing pressures. In one part of the wave
cycle, the gas molecules are compressed. In the other part of the wave, the gas molecules
are rarefied. Therefore, each wave contains a compression area (node) of higher pressure
and a rarefaction area (anti-node) of lower pressure. An exhaust pipe of the proper length
(for a specific RPM range) will place the wave’s anti-node at the exhaust valve at the
proper time for it’s lower pressure to help fill the combustion chamber with fresh
incoming charge and to extract spent gases from the chamber. This is wave scavenging or
"wave tuning".
From these cyclical engine events, one can deduce that the beneficial part of a rapidly
traveling reversion wave can only be present at an exhaust port during portions of the
powerband since it's relative arrival time changes with RPM. This makes it difficult to
tune an exhaust system to take advantage of reversion waves which is why there are
various anti-reversion devices designed to improve performance. These anti-reversion
devices are designed to weaken and disrupt the detrimental reversion waves (when the
wave's higher-pressure node impedes scavenging and intake draw-through). Specifically
designed performance baffles can be extremely effective, as well as heads with D shaped
ports. Unlike reversion waves that have no mass, exhaust gases do have mass. Since
they are in motion, they also have inertia (or "momentum") as they travel outward at their
comparatively slow velocity of 150 - 300 feet per second. When the gases move outward
as a gas column through the exhaust pipe, a decreasing pressure area is created in the pipe
behind them. It may help to think of this lower pressure area as a partial vacuum and one
can visualize the vacuous lower pressure "pulling" residual exhaust gases from the
combustion chamber and exhaust port. It can also help pull fresh air/fuel charge into the
combustion chamber. This is inertial scavenging and it has a major effect upon engine
power at low-to-mid range RPM.
There are other factors that further complicate the behavior of exhaust gases. Wave
harmonics, wave amplification and wave cancellation effects also play into the scheme of
exhaust events. The interaction of all these variables is so abstractly complex that it is
difficult to fully grasp. There does not appear to be any absolute formula that will
produce the perfect exhaust design. Even super-computer designed exhaust systems must
undergo dyno, track, and street testing to determine the necessary configuration for the
desired results. Last but not least, the correct choices and combinations of carburetor, air
cleaner, cam shaft, ignition, and exhaust used in the proper relationship to each other for
the intended riding application will always produce the finest quality results. Most
important of all, is to do your research prior to purchasing the combination of products
and equipment best suited to your individual style of riding.
The How & Why
No exhaust system is ideal for all applications. Depending on their design and purpose,
all exhaust systems compromise something to achieve something else. Before performing
exhaust changes or modifications to increase performance, it is critical to determine what
kind of performance you want.
* Do you want the best possible low-end and mid-range power or maximum top-end
power?
* Will you be using an aftermarket cam with different lift, duration, timing and overlap?
* Have you investigated the relationship between torque (force) and horsepower (amount
of work within time)?
* Do you want a cosmetic exhaust system or a performance exhaust system?
Without careful thought about these variables, an exhaust system can yield very
disappointing results. On the other hand, a properly designed and tuned exhaust system
that is well-matched to the engine can provide outstanding power gains.
The distinction between "maximum power" and "maximum performance" is significant
beyond general discussion. Realistically, one exhaust system may not produce both
maximum power and maximum performance. For a motorcycle to cover "X" distance as
quickly as possible, it is not the highest peak power generated by the engine that is most
critical. It is the highest average power generated across the distance that typically
produces the quickest time. When comparing two horsepower curves on a dynamometer
chart (assuming other factors remain constant), the curve containing the greatest average
power is the one that will typically cover the distance in the least time and that curve
may, or may not, contain the highest possible peak power.
In the strictest technical sense, an exhaust system cannot produce more power on its own.
The potential power of an engine is determined by the proper amount of fuel available for
combustion. However, the efficiency of combustion and engine pumping processes is
profoundly influenced by the exhaust system. A properly designed exhaust system can
reduce engine pumping losses. Therefore, the design objective for a high performance
exhaust is (or should be) to reduce engine-pumping losses, and by so doing, increase
volumetric efficiency. The net result of reduced pumping losses is more power available
to move the motorcycle. As volumetric efficiency increases, potential fuel mileage also
increases because less throttle opening is required to move the motorcycle at the same
velocity.
Much controversy (and apparent confusion) surrounds the issue of exhaust "back-
pressure". Many performance-minded people who are otherwise knowledgeable still
cling tenaciously to the old school concept.... "You need more back-pressure for better
performance."
For virtually all high performance purposes, backpressure in an exhaust system increases
engine-pumping losses and decreases available engine power. It is true that some engines
are mechanically tuned to "X" amount of backpressure and can show a loss of low-end
torque when that backpressure is reduced. It is also true that the same engine that lost
low-end torque with reduced back-pressure can be mechanically re-tuned to show an
increase of low-end torque with the same reduction of back-pressure. More importantly,
maximum mid-to-high RPM power will be achieved with the lowest possible
backpressure. Period!
The objective of most engine modifications is to maximize the proper air and fuel flow
into, and exhaust flow out of the engine. The inflow of an air/fuel mixture is a separate
issue, but it is directly influenced by exhaust flow, particularly during valve overlap
(when both valves are open for "X" degrees of crankshaft rotation). Gasoline requires
oxygen to burn. By volume, dry, ambient air at sea level contains about 21% oxygen,
78% Nitrogen and trace amounts of Argon, CO2 and other gases. Since oxygen is only
about 1/5 of air’s volume, an engine must intake 5 times more air than oxygen to get the
oxygen it needs to support the combustion of fuel. If we introduce an oxygen-bearing
additive such as nitrous oxide, or use an oxygen-bearing fuel such as nitromethane, we
can make much more power from the same displacement because both additives bring
more oxygen to the combustion chamber to support the combustion of more fuel. If we
add a supercharger or turbocharger, we get more power for the same reason…. more
oxygen is forced into the combustion chamber.
Theoretically, in a normally aspirated state of tune without fuel or oxygen-rich additives,
an engine’s maximum power potential is directly proportional with the volume of air it
flows. This means that an engine of 80 cubic inches has the same maximum power
potential as an engine of 100 cubic inches, if they both flow the same volume of air. In
this example, the powerband characteristics of the two engines will be quite different but
the peak attainable power is essentially the same.
Flow Volume & Flow Velocity
One of the biggest issues with exhaust systems, is the relationship between gas flow
volume and gas flow velocity (which also applies to the intake track). An engine needs
the highest flow velocity possible for quick throttle response and torque throughout the
low-to-mid range portion of the power band. The same engine also needs the highest flow
volume possible throughout the mid-to-high range portion of the powerband for
maximum performance. This is where a fundamental conflict arises. For "X" amount of
exhaust pressure at an exhaust valve, a smaller diameter exhaust pipe will provide higher
flow velocity than a larger diameter pipe. Unfortunately, the laws of physics will not
allow that same small diameter pipe to flow sufficient volume to realize maximum
possible power at higher RPM. If we install a larger diameter pipe, we will have enough
flow volume for maximum power at mid-to-high RPM, but the flow velocity will
decrease and low-to-mid range throttle response and torque will suffer. This is the
primary paradox of exhaust flow dynamics and the solution is usually a design
compromise that produces an acceptable amount of throttle response, torque and
horsepower across the entire powerband.
A very common mistake made by some performance people is the selection of an exhaust
system with pipes that are too large in diameter for their engine's state of tune. Bigger is
not necessarily better and is often worse.
Equal Length Exhaust
The effectiveness of equal length exhaust is widely debated.
Assuming that an exhaust system is otherwise properly designed, equal length pipes offer
some benefits that are not present with unequal length pipes. These benefits are smoother
engine operation, tuning simplicity and increased low-to-mid range torque.
If the pipes are not equal length, both inertial scavenging and wave scavenging will vary
among engine cylinders, often dramatically. This, in turn, causes different tuning
requirements for different cylinders. These variations affect air/fuel mixtures and timing
requirements, and can make it very difficult to achieve optimal tuning. Equal length pipes
eliminate these exhaust-induced difficulties. "Tuning", in the context used here, does not
mean installing new sparkplugs and an air filter. It means configuring a combination of
mechanical components to maximum efficiency for a specific purpose and it can not be
overemphasized that such tuning is the path to superior performance with a combination
of parts that must work together in a complimentary manner.
In an exhaust system that is properly designed for it’s application, equal length pipes are
generally more efficient. The lengths of both the primary and main section of pipes
strongly influence the location of the torque peak(s) within the powerband. In street and
track performance engines with longer pipes typically produce more low-to-mid range
torque than shorter pipes and it is torque that moves a motorcycle. The question is...
Where in the powerband do you want to maximize the torque?
* Longer pipes tend to increase power below the engine’s torque peak and shorter pipes
tend to increase power above the torque peak.
* Large diameter pipes tend to limit low-range power and increase high range power.
* Small diameter pipes tend to increase low-range power and to some degree limit high-
range power.
* "Balance" or "equalizer" chambers between the exhaust pipes tend to flatten the torque
peak(s) and widen the powerband.
Among the more astute and responsible exhaust builders, it is more-or-less understood
that pipe length variations should not exceed 1" to be considered equal. Even this
standard can result in a 2" difference if one pipe is an inch short and another pipe is an
inch long.
Exhaust Scavenging and Energy Waves
Inertial scavenging and wave scavenging are different phenomena but both impact
exhaust system efficiency and affect one another. Scavenging is simply gas extraction.
These two scavenging effects are directly influenced by pipe diameter, length, shape and
the thermal properties of the pipe material (stainless, mild steel, thermal coatings, etc.).
When the exhaust valve opens, two things immediately happen. An energy wave, or
pulse, is created from the rapidly expanding combustion gases. The wave enters the
exhaust pipe traveling outward at a nominal speed of 1,300 - 1,700 feet per second (this
speed varies depending on engine design, modifications, etc., and is therefore stated as a
"nominal" velocity). This wave is pure energy, similar to a shock wave from an
explosion. Simultaneous with the energy wave, the spent combustion gases also enter the
exhaust pipe and travel outward more slowly at 150 - 300 feet per second nominal
(maximum power is usually made with gas velocities between 240 and 300 feet per
second). Since the energy wave is moving about 5 times faster than the exhaust gases, it
will get where it is going faster than the gases. When the outbound energy wave
encounters a lower pressure area such as a second or larger diameter section of pipe, the
muffler or the ambient atmosphere, a reversion wave (a reversed or mirrored wave) is
reflected back toward the exhaust valve without significant loss of velocity.
The reversion wave moves back toward the exhaust valve on a collision course with the
exiting gases whereupon they pass through one another, with some energy loss and
turbulence, and continue in their respective directions. What happens when that reversion
wave arrives at the exhaust valve depends on whether the valve is still open or closed.
This is a critical moment in the exhaust cycle because the reversion wave can be
beneficial or detrimental to exhaust flow, depending upon its arrival time at the exhaust
valve. If the exhaust valve is closed when the reversion wave arrives, the wave is again
reflected toward the exhaust outlet and eventually dissipates its energy in this back and
forth motion. If the exhaust valve is open when the wave arrives, its effect upon exhaust
gas flow depends on which part of the wave is hitting the open exhaust valve.
A wave is comprised of two alternating and opposing pressures. In one part of the wave
cycle, the gas molecules are compressed. In the other part of the wave, the gas molecules
are rarefied. Therefore, each wave contains a compression area (node) of higher pressure
and a rarefaction area (anti-node) of lower pressure. An exhaust pipe of the proper length
(for a specific RPM range) will place the wave’s anti-node at the exhaust valve at the
proper time for it’s lower pressure to help fill the combustion chamber with fresh
incoming charge and to extract spent gases from the chamber. This is wave scavenging or
"wave tuning".
From these cyclical engine events, one can deduce that the beneficial part of a rapidly
traveling reversion wave can only be present at an exhaust port during portions of the
powerband since it's relative arrival time changes with RPM. This makes it difficult to
tune an exhaust system to take advantage of reversion waves which is why there are
various anti-reversion devices designed to improve performance. These anti-reversion
devices are designed to weaken and disrupt the detrimental reversion waves (when the
wave's higher-pressure node impedes scavenging and intake draw-through). Specifically
designed performance baffles can be extremely effective, as well as heads with D shaped
ports. Unlike reversion waves that have no mass, exhaust gases do have mass. Since
they are in motion, they also have inertia (or "momentum") as they travel outward at their
comparatively slow velocity of 150 - 300 feet per second. When the gases move outward
as a gas column through the exhaust pipe, a decreasing pressure area is created in the pipe
behind them. It may help to think of this lower pressure area as a partial vacuum and one
can visualize the vacuous lower pressure "pulling" residual exhaust gases from the
combustion chamber and exhaust port. It can also help pull fresh air/fuel charge into the
combustion chamber. This is inertial scavenging and it has a major effect upon engine
power at low-to-mid range RPM.
There are other factors that further complicate the behavior of exhaust gases. Wave
harmonics, wave amplification and wave cancellation effects also play into the scheme of
exhaust events. The interaction of all these variables is so abstractly complex that it is
difficult to fully grasp. There does not appear to be any absolute formula that will
produce the perfect exhaust design. Even super-computer designed exhaust systems must
undergo dyno, track, and street testing to determine the necessary configuration for the
desired results. Last but not least, the correct choices and combinations of carburetor, air
cleaner, cam shaft, ignition, and exhaust used in the proper relationship to each other for
the intended riding application will always produce the finest quality results. Most
important of all, is to do your research prior to purchasing the combination of products
and equipment best suited to your individual style of riding.
_________________
2007 Bandit 1250sa Silver
*Open airbox lid with K&N.
*Removed Secondaries.
*HealTech Gear Indicator w/tre "Advanced Timing Retard Eliminator is needed".
*Balanced TB's. My TPS was fine, but you should check yours.
*Arrow race headers with Yoshimura TRS.
*PC3 with the supplied map and these mod got 123hp with 115nm of torque.
*Neville Lush Racing custom tune = 130hp with 125nm at the Tyre (Standard 98hp/108nm).
My youtube channel (clickhere)
Reardo- Posts : 2192
Join date : 2010-02-06
Age : 44
Location : BROKEN HILL -
Re: Understanding Exhaust
ClaytonFirth Fri 18 Mar 2011, 8:35 am
Great article.... Too long to try and read it all at 7:30 in the morning though... I got about half way..
ClaytonFirth- Posts : 26
Join date : 2011-02-17
Age : 47
Location : Brisbane
Re: Understanding Exhaust
Saikhan Fri 18 Mar 2011, 9:11 pm
Read the first 2 lines. Maybe later. 
I'll let Yoshimura do the work for me.
I'll let Yoshimura do the work for me.
Saikhan- Posts : 765
Join date : 2010-01-19
Age : 58
Location : Gladstone Qld.
Re: Understanding Exhaust
gus Fri 18 Mar 2011, 9:33 pm
Thats all well and good but what about the SOUND.
gus- Posts : 6176
Join date : 2010-11-23
Age : 73
Location : Cygnet ,Tasmania
Re: Understanding Exhaust
Thof Fri 18 Mar 2011, 9:40 pm
Strewth! I think Reardo is saying pipes 'n cans are a compromise, the compromise is where you ride, how you ride, what performance you want from your ride, and of course, how it looks. Whew, lots of words and stuff to take in! Gr8 stuff Reardo, did you have an RDO or something to get this out!?
Thof- Posts : 224
Join date : 2010-10-28
Age : 62
Location : Sunbury
Re: Understanding Exhaust
2wheelsagain Fri 18 Mar 2011, 9:55 pm
Tomorrows subject; Velocity Stacks 
_________________
My posts reflect my personal experience or opinion. You don't have to agree with me.
~ Chris ~~ 0466 Ask ~
~ My Photography Blog Page ~
~ My YouTube Channel ~
~ Suzuki Bandits Australia Facebook Page ~
~ Half hr from the hills. Two minutes from the coast ~
~ My Bike ~
BMW R1250RS
2wheelsagain- Admin
- Posts : 6390
Join date : 2009-08-26
Age : 59
Location : Sale Area Vic -
Re: Understanding Exhaust
Reardo Fri 18 Mar 2011, 10:37 pm
What I got from it (i think) was. I can fully unrestrict my Bandit, like Airbox lid opened, K&N air filter, Remove the secondaries butterflies, Remove the catalytic converter and slip-on can & get power with losing torque 
me 2.Saikhan wrote:I'll let Yoshimura do the work for me.
haha It took all RDO to read, and only a min to copy & paste from Aussie Street Bikes.Thof wrote:Strewth! I think Reardo is saying pipes 'n cans are a compromise, the compromise is where you ride, how you ride, what performance you want from your ride, and of course, how it looks. Whew, lots of words and stuff to take in! Gr8 stuff Reardo, did you have an RDO or something to get this out!?
_________________
2007 Bandit 1250sa Silver
*Open airbox lid with K&N.
*Removed Secondaries.
*HealTech Gear Indicator w/tre "Advanced Timing Retard Eliminator is needed".
*Balanced TB's. My TPS was fine, but you should check yours.
*Arrow race headers with Yoshimura TRS.
*PC3 with the supplied map and these mod got 123hp with 115nm of torque.
*Neville Lush Racing custom tune = 130hp with 125nm at the Tyre (Standard 98hp/108nm).
My youtube channel (clickhere)
Reardo- Posts : 2192
Join date : 2010-02-06
Age : 44
Location : BROKEN HILL -
Re: Understanding Exhaust
Saikhan Sat 19 Mar 2011, 11:35 am
Hey Reardo, I was on youtube last night and saw a video (sort of) of a Yoshi cf pipe being cut down. It was posted by a Reardo38. You in another lifetime??
Saikhan- Posts : 765
Join date : 2010-01-19
Age : 58
Location : Gladstone Qld.
Re: Understanding Exhaust
Reardo Sat 19 Mar 2011, 3:15 pm
This the thread on here.Saikhan wrote:Hey Reardo, I was on youtube last night and saw a video (sort of) of a Yoshi cf pipe being cut down. It was posted by a Reardo38. You in another lifetime??
6months ago mate. This is the link to my bandit video clips, on my Youtube channel.in another lifetime??
_________________
2007 Bandit 1250sa Silver
*Open airbox lid with K&N.
*Removed Secondaries.
*HealTech Gear Indicator w/tre "Advanced Timing Retard Eliminator is needed".
*Balanced TB's. My TPS was fine, but you should check yours.
*Arrow race headers with Yoshimura TRS.
*PC3 with the supplied map and these mod got 123hp with 115nm of torque.
*Neville Lush Racing custom tune = 130hp with 125nm at the Tyre (Standard 98hp/108nm).
My youtube channel (clickhere)
Reardo- Posts : 2192
Join date : 2010-02-06
Age : 44
Location : BROKEN HILL -
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