FMF Factory 4.1C User manual

Factory4.1C
TM
Installation
Thank you for purchasing the FMF Factory4.1CTM muffler for your Yamaha YZ/WR450F
. We have spent
countless hours of R & D and testing to insure you receive the highest quality product on the market today.
All FMF's products are developed using the most current technology available for design and manufacturing.
We use only the highest quality materials for function and durability. The Factory4.1CTM
muffler is constructed of
a carbon fiber canister with a titanium mandrel bent mid-pipe. Tru-Flo modular titanium endcaps are fitted to both
ends and we utilize advanced 3-stage sound absorption packing material.
The Factory4.1CTM
muffler is the lightest slip on muffler available and specifically engineered to broaden
your existing powerband to give you an all-around power increase. Bolt on FMF performance and FEEL THE
POWER!
Check out our website at www.fmfracing.com for more information.
Please read all instructions thoroughly before installation
. Failure to follow all installation instructions completely will void any
FMF warranty implied or otherwise. FMF Racing will not be held responsible for problems derived from improper installation and/or improper
usage. Before you begin installing this product, be sure you are wearing eye protection and gloves. You should have a complete
understanding of how to remove and replace your stock exhaust. Otherwise, you should have it installed by a professional mechanic. Keep all
OEM parts when removing your stock exhaust, as some parts may be necessary to install the FMF exhaust depending on your particular
application.
18033 S. Santa Fe Ave.
Rancho Dominguez, CA 90221-5514
PH: 310-631-4363 FX: 310-900-5699
www.fmfracing.com
[05-05 / #000634]
‘03-05 Yamaha YZ/WR450F
1. Make sure the engine is completely cool prior to installation and the vehicle is in a stable position.
2. Remove the right plastic side panel to gain access to the muffler.
3. Loosen the band clamp connecting the muffler to the header.
4. Remove the OEM bolt that attaches the mid-pipe to the subframe. Keep for later use.
5. While holding the muffler, loosen and remove the OEM muffler mounting bolt.
6. Gently slide the muffler rearward to release it from the header. Spray WD-40 into the muffler-header
junction if it is difficult to remove.
7. Using contact cleaner, clean the section of the header where the mid-pipe slips over then lightly coat
with a bead of High Temp Silicone for an improved seal.
PARTS SUPPLIED
(1) Factory4.1 Carbon Muffler
(1) Titanium Mid-pipe
(1) 8mm x 20mm Bolt
(2) 70mm Springs
(1) Stepped Aluminum Panel Spacer
TOOLS REQUIRED
8mm Wrench
10mm Wrench
12mm Wrench
Contact Cleaner
High Temp Silicone
WD-40®
Spring Puller Tool
REMOVAL
OEM = Original Equipment Manufacturer
PRE-INSTALLATION
Carbon mufflers are less durable than titanium or aluminum and are more easily damaged from a crash
as well as normal riding. Damage to the muffler will
result from improper maintenance. Replace
packing if there is indication of packing blow out as evidenced by discoloration of muffler canister (gray
carbon weave turning brown), increased exhaust sound level or change in performance. Always
replace packing material if water gets into the muffler. Warranty is limited on this product.
ATTENTION

INSTALLATION
POST-INSTALLATION
8. Slip the FMF mid-pipe over the header until it is fully seated. Wipe off any excess silicone.
9. Install the existing OEM bolt through the subframe into the mid-pipe. Do not fully tighten at this time.
10.
Lightly coat the slip fit section of the mid-pipe where the muffler connects with a bead of High Temp Silicone
for an improved seal.
11. With clean hands, gently slide the FMF muffler onto the mid-pipe. Wipe away any excess silicone.
12. Install the supplied 8mm x 20mm bolt. Do not fully tighten at this time.
13.
Install the two (2) supplied 70mm exhaust springs from the muffler to the mid-pipe using a spring puller
tool (one spring on top, one on bottom).
14. Make sure the header and muffler are in neutral positions and not binding. Slowly tighten all mounting
fasteners and clamps to OEM specified torque specs, starting from the front and working your way back.
15.
When re-installing the right plastic side panel, replace the aluminum insert at the bottom front mounting hole
with the supplied stepped spacer. This spaces the side panel out more for proper clearance.
16. Inspect the complete exhaust to make sure there is no contact with the frame, shock spring, engine,
body panels or any cables, hoses or wiring. The exhaust system should only be in contact with the
exhaust port and mounting points. Confirm all controls operate in accordance with the manufacturer’s
specifications.
17. We recommend using High Temp Silicone for an improved seal. Please follow instructions for the
Silicone and allow sufficient time to dry before starting the engine.
18. Before operating your vehicle, we recommend either stock jetting or installing our Power-Up jetting kit
for optimum performance. Our jetting recommendations are to be used as a guide only and were
developed based on operation at sea-level at 70 degree ambient air temperature. There are too many
variables outside of FMF’s control to give you an exact specification. If you’re not capable of tuning the
carburetor yourself, please find a mechanic in your area who is capable to take on this role. Refer to our
website for more jetting information.
19. Start the engine and bring it up to operating temperature. Check for exhaust leaks.
20. Let engine cool completely and re-torque all mounting hardware to the manufacturers specifications.
To clean your FMF muffler, allow to cool and use mild soap and water. Do not spray water onto a hot exhaust. Dry completely to minimize
streaking and uneven discoloration.
As stated, carbon mufflers require more frequent repacking and must be repacked immediately if there is indication of the packing material failing.
Symptoms of packing material beginning to fail are: discoloration of the carbon canister (gray carbon weave turning brown), increased sound
level or a change in performance. Riding in the higher RPM range as opposed to the low to mid RPM range causes excessive heat which
degrades packing material at an accelerated rate. Under these circumstances, the packing will need to be replaced sooner and more frequently
or the carbon canister will be damaged. Water will ruin the packing. Cover the exhaust outlet when washing your machine. Repack your muffler
if water enters the chamber. Use only FMF Racing’s Carbon Muffler Repacking Kit, part number 012331, and follow the installation instructions
provided for repacking the Factory 4.1 muffler. Warranty is void if other packing material is used. We also recommend cleaning the spark arrestor
screen (if equipped) gently using a wire brush after every 30 hours of use.
MAINTENANCE
Disclaimer
FMF Racing inspects all products prior to packaging and strives toward improving its products. Our guarantee is limited to the replacement of defective
products. This limited guarantee is in lieu of all other guarantees or warranties implied or expressed. Buyer assumes all risk for any and all damage caused to
himself, a third party and/or property by virtue of failure of this product. We make no warranty as to products distributed by FMF Racing, expressed or implied
from our suppliers or 3rd party vendors. This includes, without limitation, any warranties or merchantability and fitness for a particular purpose. All products are
offered and designed for use with standard machines. FMF Racing makes no claims as to the products effectiveness on modified machines. FMF
Racing is the
sole determiner of abuse, misuse, installation errors and modifications. We assume no liability for any errors in listings, specifications, part numbers, prices or
model applications. We reserve the right to change specifications, product descriptions, product quality, pricing and application at any time without notice and
without further obligation. By installing and/or using an FMF product, you hereby accept and understand these stated terms and conditions and have followed all
instructional steps.