FMF Fatty Pipe
After a short-lived experiment with a heavy, bottom-end-boosting Gnarly pipe on
my 2003 KX250, I wanted to preserve the super-light feel of the front end.
Instead of mounting a heavy Moose steel guard around the stock pipe, I bought
an inventory of cheap stock pipes from eBay from motocross guys who wanted
shiny pipes instead of black ones. Once or twice a year I'd bang the crap out of
a pipe, pull it off the bike, throw it in the trash and bolt on a $50 replacement.
This continued with the 2004 KX250 for about half the 2006 season. After
moving out of St. Louis, for some reason the dents came more often and with
much greater force in Illinois than Missouri. I was going through pipes like a
Nicole Richie supply of Exlax. A year earlier I'd found an FMF Fatty pipe on eBay
for about $70 delivered to my door, which by mid-2006 was the last spare pipe
in my inventory. I installed it just before a Wedron, Illinois hare scramble and
used it the rest of the year.
The difference between the Fatty and the stock KX250 pipe was small but
noticeable: a little more throttle response; a bit more "pep" in the engine.
Power-wise, I couldn't tell much difference. My version of the Fatty was the
"Factory" model, which was just like the regular version except it didn't have a
shiny nickel plating. It appears FMF skipped the nickel plating process to give
the pipe a rough appearance like those found on factory motocross racers. It's
marketing genius: motocross racers hand over an extra $20 or so and get a
pipe that would seem to cost less to manufacture. The downside is that it
always looked rusty. But hey, I'm an off-roader. The only places my bike shines
are where I've applied fresh duct tape.
The Fatty pipe was also a replacement for the stock Akrapovic pipe on my 2009
KTM 250XC. The stock pipe is fine performance-wise, but it was made to be
very light weight and less than ideal for the rigors of off-road racing. Even with a
carbon fiber pipe guard, the mounts cracked and the small end of the pipe
eventually got pushed in. The Fatty pipe is a good substitute for strength
(although not it in the same category as the Gnarly); performance is no different
than the stock pipe. If I could do it over again, I'd ditch the stock pipe before I
ever rode the bike, sell it on eBay and recoup some of the cost of the FMF pipe
(which I would be buying at some point anyway).
FMF Gnarly Pipe
In the late 1990's, FMF developed a new pipe specific to off-road 2-stroke
motorcycles which promised to deliver more low-end power. The Gnarly was
designed to offer more "grunt" at lower RPM's and provide resistance to dents,
which for you younger folks who've never owned a 2-stroke dirt bike, is
something that happens pretty often when there's a big fat piece of metal pipe
hanging low out the front side of the engine. I was really not interested in
repairing or replacing pipes on a regular basis, so I ordered up a Gnarly for my
1999 KTM 300EXC when its stock pipe expired. In an effort to avoid any
possibility of dents on my expensive new pipe, I added a Moose Racing steel
pipe guard.
The Gnarly/Moose combo proved to be virtually indestructible. It also proved to
be extremely heavy. I never did a weight comparison, but I would guess I added
a solid 5 pounds or more. This combo worked so well on the '99 EXC that I did
the same for my 2002 KTM 300MXC, with similar results. I was having such
good luck with the Gnarly, I figured what the heck, I'll put one on my 2003 KX250.
That's where the Gnarly lost its luster. While the pipe did add some low-end
power to the KX, it took away more than I wanted from the top end. The KTM
300s, in contrast, were so tuned for low-end power (at the expense of top-end
response) that the Gnarly didn't make much difference in power delivery. The
KX250's, on the other hand, were screamers who demanded to be ridden in the
upper-RPM ranges. Loss of top-end power was more of sacrifice than I was
willing to make. Thus, the Gnarly went to a new eBay home after only a couple
rides.
With the advent of carbon fiber pipe guards, I began using Fatty pipes when the
stock pipes on my various motorcycles wore out. The carbon fiber guards do a
great job in protecting pipes and add very little weight. The need for pipe
strength has lessened, and so did my love affair with the Gnarly.
FMF Turbine Core
The FMF Turbine Core is a silencer/spark arrestor that is legal for use in
enduros and government-owned riding areas. It's a few inches shorter than the
elongated silencers from the early-2000's KTM's but slightly longer than the
stock silencer on a KX250. Sound levels are comparable to stock silencers,
with the exhaust note on the KX just a bit softer. Back in the EXC/MXC days of
KTM, the stock silencers were notorious for dripping black oily spooge, and the
FMF Turbine Core helped clean that up somewhat. Some dripping remained,
but the whole exhaust system became more free-flowing. Instead of spooge
dripping onto the brake caliper and pads, it blew out the back end and sprayed
my jersey with tiny black dots. Quality is typical FMF, which means it's top-notch
and installation was simple. The Turbine Core uses all of the stock mounting,
which means you have to pull off the rubber bushings on the stock unit. I used
a Turbine Core on my first two KTM's in conjunction with various FMF pipes. For
the 2007 Leadbelt Enduro, I installed a Turbine Core on the 2004 KX250 to
meet spark arrestor requirements. It worked just fine, so I left it on for the rest of
the years I owned that bike.
The only issue I ever had with a Turbine Core was at the July 2001 Tebbetts,
Missouri hare scramble. On that day I was riding my 1999 KTM 300EXC and the
stinger tube broke off from the silencer body. I called the FMF warranty
department and they agreed to replace it free of charge, even though it was
about 8 months past its warranty. Apparently the KTM's had enough flex in the
pipe/silencer joint that several FMF silencers had broken on the KTM's.
Probably didn't help that my sub-frame had a slight tweak (thanks to Belleville in
'99) that caused the mounts to be off slightly, requiring a bit of persuasion to get
the silencer mounted. Over time, that was probably what caused the weakness
that broke the thing. The new Turbine Core appeared to have a thicker weld
where the stinger tube met the silencer body.
I bought a slightly used Turbine Core for my 2003 KX250 and never used it until
the AMA's National Enduro Series went to a closed-course, rally-style format in
2007 that required no timekeeping. Without the need for an odometer, I brought
the 2004 KX250 to the Leadbelt Enduro and bolted on the Turbine Core. It
passed the sound test and didn't affect power delivery at any noticeable level.
One of the downsides to the Turbine Core is that if you want to fully
disassemble it down to the end cap, rivets must be drilled out and replaced
with some other type of fastener (unless you have the tools to re-rivet the end
cap). About the only thing I've found that works halfway decent is very
large-diameter sheet metal screws. The challenge is finding a "fat" enough
screw to match the diameter of the internal clips that hold the insides of the end
cap against the outer shell. The next challenge is keeping the screws from
falling out. The best I could do is #14 sheet metal screws, 3/4" long. This does
require drilling to make the original rivet holes a little larger. The only way I've
found to effectively keep the screws in place is dipping them in JB Weld and
screwing them in (they'll still come out the next time you need to disassemble
the end cap).
Moose Racing Steel Pipe Guard
One word: STRONG! Six more words: Pain in the ass to install! But well worth
the effort because it's never suffered any damage whatsoever. Thick
construction makes it difficult to shape around the pipe, but a large rubber
mallet and a lot of pounding will eventually get it mounted properly (a vice helps;
also, I used a floor jack stand to aid in the pounding/shaping). The guard is
relatively light, not too expensive and will probably never break. Good stuff.
E-Line Carbon Fiber Pipe Guard
When I bolted on a new FMF Fatty pipe for my '04 KX250, I decided it was time to
step up and give it some real protection. To preserve the light feel of the KX's
front end, I wanted to go light, so I shelled out some serious dough and picked
up an E-Line pipe guard. These are not cheap - about $140 - but they are
simple to install and very lightweight. The only downside besides price is they
do scuff easily. However, for me, the word "scuff" is completely neutral as it
applies to my dirt bikes. This is the guard to have. I'm now using one on my
KTM 250XC.
After a short-lived experiment with a heavy, bottom-end-boosting Gnarly pipe on
my 2003 KX250, I wanted to preserve the super-light feel of the front end.
Instead of mounting a heavy Moose steel guard around the stock pipe, I bought
an inventory of cheap stock pipes from eBay from motocross guys who wanted
shiny pipes instead of black ones. Once or twice a year I'd bang the crap out of
a pipe, pull it off the bike, throw it in the trash and bolt on a $50 replacement.
This continued with the 2004 KX250 for about half the 2006 season. After
moving out of St. Louis, for some reason the dents came more often and with
much greater force in Illinois than Missouri. I was going through pipes like a
Nicole Richie supply of Exlax. A year earlier I'd found an FMF Fatty pipe on eBay
for about $70 delivered to my door, which by mid-2006 was the last spare pipe
in my inventory. I installed it just before a Wedron, Illinois hare scramble and
used it the rest of the year.
The difference between the Fatty and the stock KX250 pipe was small but
noticeable: a little more throttle response; a bit more "pep" in the engine.
Power-wise, I couldn't tell much difference. My version of the Fatty was the
"Factory" model, which was just like the regular version except it didn't have a
shiny nickel plating. It appears FMF skipped the nickel plating process to give
the pipe a rough appearance like those found on factory motocross racers. It's
marketing genius: motocross racers hand over an extra $20 or so and get a
pipe that would seem to cost less to manufacture. The downside is that it
always looked rusty. But hey, I'm an off-roader. The only places my bike shines
are where I've applied fresh duct tape.
The Fatty pipe was also a replacement for the stock Akrapovic pipe on my 2009
KTM 250XC. The stock pipe is fine performance-wise, but it was made to be
very light weight and less than ideal for the rigors of off-road racing. Even with a
carbon fiber pipe guard, the mounts cracked and the small end of the pipe
eventually got pushed in. The Fatty pipe is a good substitute for strength
(although not it in the same category as the Gnarly); performance is no different
than the stock pipe. If I could do it over again, I'd ditch the stock pipe before I
ever rode the bike, sell it on eBay and recoup some of the cost of the FMF pipe
(which I would be buying at some point anyway).
FMF Gnarly Pipe
In the late 1990's, FMF developed a new pipe specific to off-road 2-stroke
motorcycles which promised to deliver more low-end power. The Gnarly was
designed to offer more "grunt" at lower RPM's and provide resistance to dents,
which for you younger folks who've never owned a 2-stroke dirt bike, is
something that happens pretty often when there's a big fat piece of metal pipe
hanging low out the front side of the engine. I was really not interested in
repairing or replacing pipes on a regular basis, so I ordered up a Gnarly for my
1999 KTM 300EXC when its stock pipe expired. In an effort to avoid any
possibility of dents on my expensive new pipe, I added a Moose Racing steel
pipe guard.
The Gnarly/Moose combo proved to be virtually indestructible. It also proved to
be extremely heavy. I never did a weight comparison, but I would guess I added
a solid 5 pounds or more. This combo worked so well on the '99 EXC that I did
the same for my 2002 KTM 300MXC, with similar results. I was having such
good luck with the Gnarly, I figured what the heck, I'll put one on my 2003 KX250.
That's where the Gnarly lost its luster. While the pipe did add some low-end
power to the KX, it took away more than I wanted from the top end. The KTM
300s, in contrast, were so tuned for low-end power (at the expense of top-end
response) that the Gnarly didn't make much difference in power delivery. The
KX250's, on the other hand, were screamers who demanded to be ridden in the
upper-RPM ranges. Loss of top-end power was more of sacrifice than I was
willing to make. Thus, the Gnarly went to a new eBay home after only a couple
rides.
With the advent of carbon fiber pipe guards, I began using Fatty pipes when the
stock pipes on my various motorcycles wore out. The carbon fiber guards do a
great job in protecting pipes and add very little weight. The need for pipe
strength has lessened, and so did my love affair with the Gnarly.
FMF Turbine Core
The FMF Turbine Core is a silencer/spark arrestor that is legal for use in
enduros and government-owned riding areas. It's a few inches shorter than the
elongated silencers from the early-2000's KTM's but slightly longer than the
stock silencer on a KX250. Sound levels are comparable to stock silencers,
with the exhaust note on the KX just a bit softer. Back in the EXC/MXC days of
KTM, the stock silencers were notorious for dripping black oily spooge, and the
FMF Turbine Core helped clean that up somewhat. Some dripping remained,
but the whole exhaust system became more free-flowing. Instead of spooge
dripping onto the brake caliper and pads, it blew out the back end and sprayed
my jersey with tiny black dots. Quality is typical FMF, which means it's top-notch
and installation was simple. The Turbine Core uses all of the stock mounting,
which means you have to pull off the rubber bushings on the stock unit. I used
a Turbine Core on my first two KTM's in conjunction with various FMF pipes. For
the 2007 Leadbelt Enduro, I installed a Turbine Core on the 2004 KX250 to
meet spark arrestor requirements. It worked just fine, so I left it on for the rest of
the years I owned that bike.
The only issue I ever had with a Turbine Core was at the July 2001 Tebbetts,
Missouri hare scramble. On that day I was riding my 1999 KTM 300EXC and the
stinger tube broke off from the silencer body. I called the FMF warranty
department and they agreed to replace it free of charge, even though it was
about 8 months past its warranty. Apparently the KTM's had enough flex in the
pipe/silencer joint that several FMF silencers had broken on the KTM's.
Probably didn't help that my sub-frame had a slight tweak (thanks to Belleville in
'99) that caused the mounts to be off slightly, requiring a bit of persuasion to get
the silencer mounted. Over time, that was probably what caused the weakness
that broke the thing. The new Turbine Core appeared to have a thicker weld
where the stinger tube met the silencer body.
I bought a slightly used Turbine Core for my 2003 KX250 and never used it until
the AMA's National Enduro Series went to a closed-course, rally-style format in
2007 that required no timekeeping. Without the need for an odometer, I brought
the 2004 KX250 to the Leadbelt Enduro and bolted on the Turbine Core. It
passed the sound test and didn't affect power delivery at any noticeable level.
One of the downsides to the Turbine Core is that if you want to fully
disassemble it down to the end cap, rivets must be drilled out and replaced
with some other type of fastener (unless you have the tools to re-rivet the end
cap). About the only thing I've found that works halfway decent is very
large-diameter sheet metal screws. The challenge is finding a "fat" enough
screw to match the diameter of the internal clips that hold the insides of the end
cap against the outer shell. The next challenge is keeping the screws from
falling out. The best I could do is #14 sheet metal screws, 3/4" long. This does
require drilling to make the original rivet holes a little larger. The only way I've
found to effectively keep the screws in place is dipping them in JB Weld and
screwing them in (they'll still come out the next time you need to disassemble
the end cap).
Moose Racing Steel Pipe Guard
One word: STRONG! Six more words: Pain in the ass to install! But well worth
the effort because it's never suffered any damage whatsoever. Thick
construction makes it difficult to shape around the pipe, but a large rubber
mallet and a lot of pounding will eventually get it mounted properly (a vice helps;
also, I used a floor jack stand to aid in the pounding/shaping). The guard is
relatively light, not too expensive and will probably never break. Good stuff.
E-Line Carbon Fiber Pipe Guard
When I bolted on a new FMF Fatty pipe for my '04 KX250, I decided it was time to
step up and give it some real protection. To preserve the light feel of the KX's
front end, I wanted to go light, so I shelled out some serious dough and picked
up an E-Line pipe guard. These are not cheap - about $140 - but they are
simple to install and very lightweight. The only downside besides price is they
do scuff easily. However, for me, the word "scuff" is completely neutral as it
applies to my dirt bikes. This is the guard to have. I'm now using one on my
KTM 250XC.
Click on pictures to
see larger image
see larger image
| After 2 years, the KX250 pipe guard was pretty well done. The hole is where the front wheel kicked up trail junk. But it did a fine job of protecting the pipe. |
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