Get XiED(tm)! Performance Parts

Don't let the Harley heat monster ruin your riding.
Reduce  Engine Surging
Improve Throttle Response
Reduce Engine Ping


HD 2007/2008 Engines

High Heat on 2007/08 HD engines

HD 2007/08 Performance Recommendations

Cool your exhaust temperature with the Wide Band O2 upgrade for 2007/08 HD

Harley Camshaft Specification Tables

HD Twin Cam Engine Builds
TC 128 HP 95 CID
TC 100HP Street Engine

The basics of Fuel Injection explained

Rammer Performance Air Cleaners
TC Performance Heads 100+HP

Pro Tuning on a Shade Tree Budget


Fuel Supply Modifications

The following modifications should be made to your fuel supply  whether you modify your CV carburetor or if you change the carburetor to an aftermarket.

Fuel Supply:

In order to improve fuel flow to your carburetor, you may want to drill out the gas cap. Turn over the gas cap and look at the bottom. The plastic molding SHOULD have 4 spokes but some of the bad ones had 8 spokes...8 spoke gas caps need to be replaced with a 4 spoke gas cap then the modifications can be made. The one with 4 spokes has four pads or flat spots about 1/8 inch in diameter spaced around the outside of the inner molding ring. Using a 1/16 inch bit or smaller, drill a hole in the center of each of these pads clean though to the airspace below. Do not get too enthusiastic and punch a dent or hole in the top of your gas cap. The result will be better gas tank venting now that you are using more fuel and probably riding harder and faster. There is currently some controversy about this subject so please read the Denish book for more information.

Fuel petcock:

Due to EPA regulations the stock fuel petcock on late model Harley-Davidson's has very restrictive fuel flow. There are several alternatives, but Pingel is far and away the best on the market. Excellent flow and very high quality construction with a good feel to its movement. The vacuum actuated fuel petcock on the later bikes seem to be very problematic in restricting fuel flow for bikes making over 80 horsepower. Replace this petcock with a Pingle if you are serious about performance.


These modifications are for off-road use only and are not approved by the EPA or DOT or Bill Clinton. Some people ride on the road with these modifications, but I would not know who that would be ;-) Also, the authors nor their descendants nor their ancestors are responsible for any damages due to following these instructions. If you follow them correctly and do not screw up you will not have any trouble anyhow, but there it is.


Table of Contents
Search the site 
Nightrider COPYRIGHT

Ask us a Question

Modification, Installation, Maintenance and Tuning Index  will help you find most of the information you want on one page.

How to get Professional Tuning Results at home
Testing the Innovate Motorsport LM-1 portable air fuel meter

Profession Tuning on a Shade Tree Budget

Veypor VR2 Data Logger and Instrument Panel
Video Installation and Demo
Purchase VR2

Engine Performance
How to Build a
TC96 2007 Engines
TC88 70HP Stage1  
TC95 128HP Stage 3
TC95 100HP Street
TC96 2007 Stage 1/2
EVO 64 HP Stage 1
EVO 74 HP Stage 2
EVO 82 HP Stage 3
EVO 95 HP Stage 3
883 to 1200 Upgrade
Shovelhead Modifications

New EFI for EVO and TC

Performance Gallery
Horsepower Gallery
Evolution 80
Twin Cam 88/95
Evolution Unlimited
Sportster Unlimited
Drag Strip Gallery
Land Speed Racing Gallery
CV Carburetor
Modifying the CV carb
Tuning a CV carb
Selecting a cam
Install a TC 88/95 cam
Install a Big Twin cam
Install Sportster cams

Camshaft Specifications
Twin Cam

Exhaust Systems
EVO Exhaust Testing
TC Exhaust Testing
Khrome Werks AR100 test
Making Drag Pipes Work

Shop Manual
Carburetor Troubleshooting
Finding Manifold Leaks
Cylinder Heads
Pistons and Cylinders
Belt Drive
Shop Manual Appendix
$20 Bike Lift
Plug Wires
Spark Plugs
Engine Tuning
Nitrous Oxide
Motor Oil
Stutter Box
General Information
WEB Links
Buy Books and Manuals
Performance Calculations
Estimate Horsepower
Estimate 1/4 Mile Time
Estimate Top Speed

Engine Displacement
Exhaust Length
Gear Ratios
Air Density

The Nightrider Diaries
The ramblings of a genius a, a madman and something in between.

Where is Sifton Cams?

Autocom Active-7 tested

Harley-Davidson EFI
-EFI basics explained
-EFI modifications explained

183 HP, 2 carbs, 2680cc

Copyright 1997-2006  Stephen Mullen, Oldsmar, FL -+-