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Fat Boy 4 Complete Exhaust System - 2004-2005 Honda TRX 450R

INSTALLATION INSTRUCTIONS DUNCAN RACING INTERNATIONAL, INC.


FAT BOY 4 COMPLETE EXHAUST SYSTEM

MODEL; 2004-05 Honda TRX 450


1. Remove stock exhaust system; retain (2) header nuts and the bottom muffler bolt. The Top muffler bolt will be replaced with the enclosed 8x60mm bolt.

2. It is strongly recommended using new exhaust gasket to ensure an excellent seal at the head pipe. These gaskets are an original Honda part # 18291-MEB-670 and can be purchased at any Honda dealership. For maximum performance and reliability it is very important that this gasket is in good condition when your Fat Boy 4 is installed.

3. Install header in exhaust port and hand tighten.

4. Once the header is installed, you are now ready to install the tail pipe/muffler
assembly. The tail section is secured to the Fat Boy 4 muffler at the factory before shipping. If these (4) 6mm stainless button head allen screws are ever loosened or removed they must be reinstalled with some form of medium strength thread lock (recommended Loctite 242 Blue).
Before sliding tail section onto header it is recommended to apply a thin coat of hi-temp silicone to the inside of the tail section (female side) approximately covering about ½” of the initial part of the tail pipe. This will keep exhaust from leaking at the slip-fit joint and make removing pipe in future easier.

5. Before installing tail pipe/muffler assembly bolts, replace top 8mm muffler mount bolt with the enclosed 8x60 bolt, use stock oem nut. Then install stock oem nut and bolt on lower muffler mount.

6. Now that your complete exhaust system is in place, survey the overall fit
before final tightening. (make sure there is minimum 3/16” clearance between clutch cover and pipe as header turns behind frame)
To secure, tighten the (2) muffler bolts first, secondly tighten the (2) header nuts (in a even pattern).

7. Optional but recommended water hose protection. Enclosed is piece of rubber
hose and (2) zip ties. It is recommended to secure extra rubber piece over stock water pump return hose below Fat Boy 4 header pipe and above engines water pump. Attach with zip ties. Make sure zips ties are not over tightened, which could restrict coolant line flow. Make sure zip ties do not touch exhaust header.

8. Re-Jetting the carburetor is mandatory.
In normal riding conditions, using a stock engine, DR recommends using a
K & N Filter with an outerwear. With Air Box lid removed.
For temperatures 60° to 90° the following carburetor settings are recommended:
#180 to a #185 main jet will be required.
#50 or #52 Pilot Jet (setting will vary depending on conditions)
Stock needle. Clip on needle must be moved down 1 position to the 4th position.

*If air lid and or foam type air filter is used a leaner main jet setting will be required. It is recommended to call the DRI tech line (619) 258-6308 for additional help if required.

9. After running machine with your new system for approximately 10 minutes,
you should check that all nuts and bolts are tight. Pay special attention to
The (2) head pipe nuts. As exhaust gaskets warm up head pipe nuts
must be re-tightened. These nuts should be checked 3 or 4 times in the first
hour or so of riding.

*DRI has included at no charge the necessary jets for the above jetting changes with an extra main jet each way

The above specs should be an excellent starting point for most installations.
Jetting should be checked after install.

Be careful not to run machine to lean-engine damage may result. To rich power will be lost.

Jetting Notes:
Colder temperature requires richer settings.
Higher elevations cause engine to be low on compression and generally require leaner settings.
Air box lid on requires leaner settings than with lid off.

For Questions or Technical assistance, contact;

DUNCAN RACING INTERNATIONAL, INC
10734 Kenney Street Suite A
Santee, California 92071
USA

Phone (619) 258-6306
FAX (619) 258-6309


DRI also carries a complete line of World Championship winning performance items for your Honda TRX 450.

Complete Engine kits, Big Bore kits, Pistons, Cams, Porting, Carburetor Kits
Plus, Front Bumpers, Roll Design Suspension, Crown Series Brake lines, Elka Shocks.

For more info check out our website. www.duncanracing.com

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