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"Not Free"
Upgrades: Exhaust
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AfterMarket Exhaust |
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Upgrading to an aftermarket exhaust is typically one of the first upgrades
most riders will do, especially those who race. Almost all aftermarket exhaust
systems provide a noticeable increase in performance and provide a significant
weight savings over the stock exhaust. However, most are also quite expensive,
are generally louder than the stock system, and will require re-jetting the
carburetor as well. Most companies now make “quiet
core” inserts that reduce the noise output, however, the increase in performance
is diminished as well. Most aftermarket exhaust systems also include an option for
a USFS approved spark arrestor (see below).
There are numerous options when it comes the aftermarket
exhaust systems. Each system will have its own characteristics and will affect
the powerband of the bike in a unique way. Based on a review of the TT
archives, most TT members like the following systems for the 250F. For more
information on these systems, as well as others, search the TT archives and
visit the manufactures websites (see links section).
One of the limitations of a complete aftermarket exhaust is they typically
lack a header guard. Flatland Racing makes clamps that allow placing the OEM
header guard on aftermarket headers.
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Stock YZF Pipe on the WRF |
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Owners of the WRF also have another option. Since the
majority of YZ250F owners replace their stock exhaust with an aftermarket
system, there are a lot of stock YZF stock systems that are available for a
very reasonable price. Although they are not as good as an aftermarket exhaust,
the stock YZF system does provide an increase in performance and is lighter
than the stock WRF system (~3 lbs). Both the
TT for sale forums and
Ebay are
good sources for YZF stock systems. I picked mine up on Ebay for $50, complete
with header.
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The stock YZF system does not have a spark arrestor. Aftermarket options are available (see below). |
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The mounting hardware for the
stock YZF system is different from the WRF system. You will need a longer bolt
for the subframe mount, a rubber damper, a spacer, a large fender washer, and a
different slip joint (unless they came with your used system). The OEM part
numbers for the mounting hardware can be found in the Yamaha Part
Numbers section. These parts are also
available from Dr. D. |
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The WRF will need to be
re-jetted after installing the YZF pipe, especially if the other free mods have
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Here’s the YZ250F exhaust with a ProMoto Billet spark arrestor on my WR250F:
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2003 marks the time that
all off-road motorcycles used on California public lands must be equipped
with a muffler that emits no more than 96 decibels of audible sound. Many
companies have begun to make quiet inserts for OEM exhaust systems or new
"offroad" quiet exhaust systems that still offer a performance gain over
OEM systems. For sound testing procedures click here.
FMF
Big Gun
CRD |
Vortip for WRF
If you ride in public lands you may want a quieter exhaust.
One solution is to get a Vortip replacement baffle for the stock exhaust. The
Vortip replaces the OEM baffle. It increases exhaust flow
for stronger performance, yet maintains a low sound level by tuning the sound
waves downward. It apparently increases performance over 5hp at 8500rpm. It is
made from 304 stainless steel. It is effective, but most TT
riders think it actually robs some power from the bike. Also, it extends quite
a bit beyond the stock silencer. Apparently as of early 2003, the
Vortip will no longer be available.
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Thumper Racing WRF Insert
The original performance-endcap inserts. Thumper Racing offers its
turned-down inserts WRFs. This insert lowers the WR450F to 96dB. Price
$79.00.
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Baja Designs Baja Baffle for WRF
Baja Designs has created a simple and inexpensive solution to comply with the
new State Law by producing a baffle which easily surpasses the new state
regulation. In addition, the Baja Baffle will pass the even more strict
Michigan 94 dB requirements. The baffle is constructed of durable
stainless steel with a clean looking polished end cap. They have baffles
for all of the WRFs (250F, 400F, 426F and the 450F). The device simply
slides into the OEM muffler and is held securely in place by means of a
setscrew. Price: $99.95. www.bajadesigns.com.
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Yamaha OEM GYT-R Insert for WRF
This insert is quieter than the
stock YZF exhaust. It is louder that stock WRF exhaust with the baffle
installed, but not offensive and quieter than the stock WRF exhaust with
the baffle removed. It results in a much better throttle response
compared to stock WRF muffler with the baffle installed. The info sheet that
comes with the insert says: "NOTE: This muffler insert kit when properly
installed in the stock muffler conforms to United States Forest Service
noise regulations in effect as of January 1, 2003." Part number:
GYT-5TJ93-75-00.
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ProMotoBillet Silent Insert for YZF Endcap
PMB produces a removable silent insert for
use with their spark arrestor endcaps (see below), for $29.95,
that apparently reduces noise output by 5 db.
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ProMotoBillet WRF Insert
Throw away the stock baffle
that comes with your bike because it is simply too restrictive! Without
the baffle the bike is unreasonably loud! Here is the solution. The
silent insert simply replaces the stock baffle. Extensive back-pressure
testing was done to achieve maximum flow-rate and still be below the 96 db
law!
 
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The YZF stock exhaust does not have a spark arrestor. If you ride in public
lands most likely you will be required to have a US Forestry Service approved
spark arrestor on your bike. You will either need to get an aftermarket
silencer, buy an aftermarket spark arrestor to attach to your stock silencer, or
engineer a homemade spark arrestor. Whether option 3 is viable depends on how
the rangers in your area check your spark arrestor. In many areas the simply
apply the “stick” test. If the can not pass a stick through your silencer, you
pass. Others may want to see the USFS stamp of approval on the silencer endcap. The stock WRF
pipe does have a USFS approved spark arrestor. |
ProMotoBillet
PMB makes a replacement endcap for the YZF exhaust that includes a spark arrestor.
PMB also makes a removable silencer insert, for an additional $29.95,
that apparently reduces noise output by 5 db. Price $119.95.
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| Bills Motorcycles Plus
Bills makes a unit with tunable discs similar to some aftermarket exhausts like White Bros or FMF. You
can use Bill’s endplate or the one form the FMF MegaMax (supplied by Bill). The
FMF plate has the USFS approval stamp (Bill’s does not). Price $129.95. |
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Dr.D Spark Arrestor End-cap
Now you can be spark arrestor-legal on your YZ-F or CRF moto thumper. The $99
Dr. D end-cap replaces the stacker with a USFS-approved screen-type unit that
even allows you to tune the exhaust via different size tips. Price $99.99. |
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BBR
USDA Forest Service approved spark arrester installs into the production
muffler. This screen type spark arrester makes your stock pipe Forest Service
legal. The screen is easy to clean or replace. Includes drill bit and mounting
instructions. Manufactured from billet aluminum. Yamaha model is blue anodized.
Price $149.95. |
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Homemade
Here are a few links from the TT archives with some ideas of how to fashion a homemade
spark arrestor.
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