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  • FMF Gnarly Pipe 021053

    FMF Gnarly Pipe 021053

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $300.95
  • FMF Fatty Pipe 023055

    FMF Fatty Pipe 023055

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $300.95
  • FMF Fatty Pipe 025119 FMF Fatty Pipe 025119

    FMF Fatty Pipe 025119

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $300.95
  • FMF Gnarly Pipe 025131 FMF Gnarly Pipe 025131

    FMF Gnarly Pipe 025131

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $330.95
  • FMF Factory Fatty Pipe 025133 FMF Factory Fatty Pipe 025133

    FMF Factory Fatty Pipe 025133

    Factory Fatty Pipe The Factory Fatty is reminiscent of the “works” or cone pipe once used by Factory Teams and it shares many of the same characteristics with its craftsmanship and material quality, Broadens and smooths out the power curve while boosting...
    $330.95
  • FMF Gnarly Pipe 025143

    FMF Gnarly Pipe 025143

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $330.95
  • FMF Fatty Pipe 024023 FMF Fatty Pipe 024023

    FMF Fatty Pipe 024023

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $290.95
  • FMF Fatty Pipe 025263

    FMF Fatty Pipe 025263

    Fatty Pipe With well over 35 years of racing experience behind it, the Fatty Gold Series pipe delivers race proven performance, The Fatty broadens and smooths out the power curve while boosting gains throughout the entire power band, more low-end, more...
    $330.95
  • FMF Gnarly Pipe 025152

    FMF Gnarly Pipe 025152

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $300.95
  • FMF Fatty Pipe 025151

    FMF Fatty Pipe 025151

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $290.95
  • FMF Fatty Pipe 021058

    FMF Fatty Pipe 021058

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $380.95
  • FMF Gnarly Pipe 025156

    FMF Gnarly Pipe 025156

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $330.95
  • FMF Fatty Pipe 025182

    FMF Fatty Pipe 025182

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $300.95
  • FMF Gnarly Pipe 025203

    FMF Gnarly Pipe 025203

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $300.95
  • FMF Factory Fatty Rev Pipe 022064

    FMF Factory Fatty Rev Pipe 022064

    Factory Fatty Rev Pipe Pipe focuses its power delivery in the middle and upper RPM of the power band, If you're running out of power up top, want more time between shifts and do a lot of deep berm or sand riding, the FMF Rev is your pipe of choice, FMF...
    $300.95
  • FMF Factory Fatty Pipe 025219

    FMF Factory Fatty Pipe 025219

    Factory Fatty Pipe The Factory Fatty is reminiscent of the “works” or cone pipe once used by Factory Teams and it shares many of the same characteristics with its craftsmanship and material quality, Broadens and smooths out the power curve while boosting...
    $300.95
  • FMF Gnarly Pipe 020082

    FMF Gnarly Pipe 020082

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $350.95
  • FMF Gnarly Pipe 020083

    FMF Gnarly Pipe 020083

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $330.95
  • FMF Fatty Pipe 020107

    FMF Fatty Pipe 020107

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $310.95
  • FMF Fatty Pipe 020150

    FMF Fatty Pipe 020150

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $310.95
  • FMF Fatty Pipe 020375

    FMF Fatty Pipe 020375

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $300.95
  • FMF Fatty Pipe 020378

    FMF Fatty Pipe 020378

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $330.95
  • FMF Fatty Pipe 020390

    FMF Fatty Pipe 020390

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $330.95
  • FMF Gnarly Pipe 021007

    FMF Gnarly Pipe 021007

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $325.95
  • FMF Fatty Pipe 022000

    FMF Fatty Pipe 022000

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $300.95
  • FMF Fatty Pipe 022006

    FMF Fatty Pipe 022006

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $330.95
  • FMF Gnarly Pipe 022007

    FMF Gnarly Pipe 022007

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $330.95
  • FMF Fatty Pipe - KFX/LT80 023037

    FMF Fatty Pipe - KFX/LT80 023037

    Fatty Pipe - KFX/LT80 FMF's Fatty Gold Series pipe broadens the powerband and provides a healthy power increase everywhere, Improved throttle response, a linear powerband and enhanced over-rev all add up to a pipe that everyone will benefit from, If...
    $300.95
  • FMF Fatty Pipe - '85-'86 ATC250R 020006

    FMF Fatty Pipe - '85-'86 ATC250R 020006

    Fatty Pipe - '85-'86 ATC250R FMF's Fatty Gold Series pipe broadens the powerband and provides a healthy power increase everywhere, Improved throttle response, a linear powerband and enhanced over-rev all add up to a pipe that everyone will benefit from,...
    $330.95
  • FMF Fatty Pipe - '87-'89 TRX250R 020014

    FMF Fatty Pipe - '87-'89 TRX250R 020014

    Fatty Pipe - '87-'89 TRX250R FMF's Fatty Gold Series pipe broadens the powerband and provides a healthy power increase everywhere, Improved throttle response, a linear powerband and enhanced over-rev all add up to a pipe that everyone will benefit from,...
    $380.95
  • FMF Fatty Pipe 020015

    FMF Fatty Pipe 020015

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $310.95
  • FMF Fatty Pipe 020020

    FMF Fatty Pipe 020020

    Fatty Pipe Computer designed and dyno tested to make power gains where each machine needs them the most, Tru-Flo stamping process ensures a perfect fit and optimum performance, Constructed of strong 19-gauge steel with a nickel-plated finish
    $330.95
  • FMF Gnarly Pipe 020024

    FMF Gnarly Pipe 020024

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $380.95
  • FMF Gnarly Pipe 020026

    FMF Gnarly Pipe 020026

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $380.95
  • FMF Gnarly Pipe 020038

    FMF Gnarly Pipe 020038

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $380.95
  • FMF Factory Fatty Pipe - KX85/100 022062

    FMF Factory Fatty Pipe - KX85/100 022062

    Factory Fatty Pipe - KX85/100 The Factory Fatty is reminiscent of the “works” or cone pipe once used by Factory Teams and it shares many of the same characteristics with its craftsmanship and material quality, Broadens and smooths out the power curve...
    $300.95
  • FMF Factory Fatty Pipe 025183

    FMF Factory Fatty Pipe 025183

    Factory Fatty Pipe The Factory Fatty is reminiscent of the “works” or cone pipe once used by Factory Teams and it shares many of the same characteristics with its craftsmanship and material quality, Broadens and smooths out the power curve while boosting...
    $300.95
  • FMF Factory Fatty Pipe - 65SX/TC65 025198

    FMF Factory Fatty Pipe - 65SX/TC65 025198

    Factory Fatty Pipe - 65SX/TC65 The Factory Fatty is reminiscent of the “works” or cone pipe once used by Factory Teams and it shares many of the same characteristics with its craftsmanship and material quality, Broadens and smooths out the power curve...
    $290.95
  • FMF Factory Fatty Pipe 025222

    FMF Factory Fatty Pipe 025222

    Factory Fatty Pipe The Factory Fatty is reminiscent of the “works” or cone pipe once used by Factory Teams and it shares many of the same characteristics with its craftsmanship and material quality, Broadens and smooths out the power curve while boosting...
    $300.95
  • FMF Factory Fatty Big Bore Exhaust 025224

    FMF Factory Fatty Big Bore Exhaust 025224

    Factory Fatty Big Bore Exhaust Based on the successful exhaust pipe used by pro riders, 19-gauge steel used on the header portion for optimum strength and durability; 20-gauge steel on body and rear section for increased weight savings, Seams are hand...
    $300.95
  • FMF Gnarly Exhaust - Sherco 025265

    FMF Gnarly Exhaust - Sherco 025265

    Gnarly Exhaust - Sherco The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh...
    $330.95
  • FMF Gnarly Exhaust - Beta 025269

    FMF Gnarly Exhaust - Beta 025269

    Gnarly Exhaust - Beta The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh...
    $330.95
  • FMF Gnarly™ Exhaust Pipe 025280 FMF Gnarly™ Exhaust Pipe 025280

    FMF Gnarly™ Exhaust Pipe 025280

    Gnarly™ Exhaust Pipe Power gains are focused toward bottom and mid, with a goal of increased tractability, Excellent off-road pipe and good for tighter tracks, Built with tough 18-gauge steel, O-rings Included
    $330.95
  • FMF Factory Fatty Pipe 025271

    FMF Factory Fatty Pipe 025271

    Factory Fatty Pipe The Factory Fatty is reminiscent of the “works” or cone pipe once used by Factory Teams and it shares many of the same characteristics with its craftsmanship and material quality, Broadens and smooths out the power curve while boosting...
    $330.95
  • FMF Gnarly Pipe 025087

    FMF Gnarly Pipe 025087

    Gnarly Pipe The FMF Gnarly pipe focuses on increasing the lower RPM horsepower and torque to get you out of the toughest terrain, When looking to add 4-stroke tractor like torque to your 2-stroke and you need a pipe to withstand the harsh elements, this...
    $330.95

2-Stroke Expansion Chambers

2-Stroke Expansion Chambers & Pipes

On a two-stroke engine, the exhaust pipe is not just a tube that routes exhaust gases away from the engine. It is an active performance component that uses the acoustic properties of exhaust pulses to improve cylinder scavenging, push fresh charge back into the combustion chamber, and generate power gains that no other single modification can deliver on a two-stroke machine. The expansion chamber pipe is tuned specifically for an RPM range, and selecting the right pipe for your engine and your riding style is one of the most impactful performance decisions a two-stroke rider makes. Get it right and the bike pulls stronger, revs more freely, and delivers power in exactly the range where you need it most. Get it wrong and you have spent money on a pipe that fights your riding style instead of complementing it.

Two-stroke expansion chambers have been refined over decades of motocross and enduro racing into some of the most precisely engineered performance components in all of powersports. The geometry of each section of the pipe, from the header diameter and taper angles through the belly and convergent cone to the stinger dimensions, is calculated to produce specific acoustic characteristics that interact with your engine's port timing at specific RPM ranges. A pipe tuned for a broad, usable powerband that pulls strong from the low-mid range through the top is a very different riding experience than a pipe tuned for a narrow, aggressive hit that builds power explosively in the upper RPM range. Understanding what each pipe is tuned for before you buy is the key to getting the result you are looking for. Mad Lads Moto stocks two-stroke expansion chambers for motocross, enduro, trail, and off-road applications across all major makes and models. Here is what we carry:

  • Motocross Pipes - High-performance expansion chambers tuned for the wide-open, high-RPM demands of motocross racing where peak power and top-end pull are the primary performance targets across both 125cc and 250cc two-stroke classes.
  • Enduro & Trail Pipes - Expansion chambers tuned for broader powerbands that deliver strong low-to-mid range torque for the technical, variable-speed demands of enduro and trail riding where tractable power across a wide RPM range matters more than peak horsepower at the top.
  • Silencers & Canisters - Two-stroke silencers and canisters that work in conjunction with the expansion chamber pipe to control backpressure, manage exhaust note, and in some cases fine-tune power delivery at the top of the RPM range.
  • Pipe Guards & Protectors - Expansion chamber guards and pipe protectors that shield the pipe from rock strikes, boot contact, and the trail debris that dents and damages two-stroke pipes in off-road environments where protecting the tuned geometry of the pipe is essential to preserving performance.
  • Pipe Springs & Hardware - Replacement pipe springs, clamps, and mounting hardware for two-stroke exhaust installations and for maintaining secure connections on existing pipe setups.

Pipe guards deserve serious consideration for any two-stroke rider who takes their machine off-road. The tuned geometry of a two-stroke expansion chamber is precisely calculated, and a dent in the wrong location changes the acoustic properties of the pipe in ways that affect power delivery across the entire RPM range. A dented expansion chamber does not just look bad. It can rob the engine of power, change where the powerband comes on, and in severe cases cause the engine to run lean from altered scavenging efficiency. A quality pipe guard that absorbs the rock strikes and boot contact that off-road riding inevitably delivers protects an investment that is significantly more expensive to replace than the guard itself. We stock two-stroke expansion chambers and accessories for Honda, Yamaha, Kawasaki, Suzuki, KTM, Husqvarna, Beta, GasGas, and more. Use our year, make, and model fitment tool to find pipes confirmed to fit your specific machine before you order.

How does a two-stroke expansion chamber work?

A two-stroke expansion chamber works by using the acoustic properties of exhaust gas pulses to improve cylinder scavenging and boost power output beyond what a simple straight pipe could achieve. When the exhaust port opens, a positive pressure wave travels down the header section of the pipe. As it reaches the diverging cone where the pipe begins to expand, part of that wave reflects back toward the cylinder as a negative pressure wave that helps draw exhaust gases out of the cylinder. As the positive wave continues to the convergent cone where the pipe narrows toward the stinger, it reflects again as a positive pressure wave that travels back toward the cylinder. When the pipe dimensions are tuned correctly, this returning positive wave arrives at the exhaust port just as the piston is closing it during the transfer phase, ramming fresh charge back into the cylinder and significantly increasing the amount of fresh mixture trapped for combustion. The RPM range at which this effect is strongest is determined by the length and dimensions of each pipe section, which is why pipe selection affects not just peak power but where in the RPM range power comes on.

Will a two-stroke expansion chamber require rejetting my carburetor?

Yes, in most cases. A performance expansion chamber changes the scavenging efficiency and breathing characteristics of the engine in ways that affect the optimal fuel and air mixture. Running a performance pipe on a two-stroke without retuning the carburetor typically results in a lean condition at the RPM range where the pipe is most effective, which reduces power gains from the pipe and in severe cases can cause piston damage from running hot and lean at peak power. Most performance pipe manufacturers provide jetting recommendations for their specific pipes on common engine applications, and starting with those recommendations before fine-tuning for your altitude and temperature is the correct approach. A fresh plug inspection after the first hard run with the new pipe confirms whether your jetting is in the correct range before committing to more riding on the new setup.

Does a dent in my two-stroke expansion chamber affect performance?

Yes, and more significantly than most riders expect. The tuned geometry of a two-stroke expansion chamber is precisely calculated to produce specific acoustic characteristics at specific RPM ranges. A dent changes the internal volume and cross-sectional area of the pipe at that location, altering the acoustic properties of the affected section and changing how the reflected pressure waves interact with the engine's exhaust port timing. Small dents in less critical areas like the belly section may have minimal effect on power delivery. Dents in the divergent or convergent cone sections where the pipe's tuning effect is most sensitive can meaningfully shift where the powerband comes on, reduce peak power, and change the character of the power delivery in ways that are immediately noticeable to an experienced rider. A severely dented pipe should be replaced rather than ridden on if performance is a priority, and installing a pipe guard before the next ride protects the replacement from suffering the same fate.
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