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


Main Jet Correction Chart

Step #1 - Assume Nothing!!! Check your carburetor(s) to verify the jetting installed in the carburetor(s).

Step #2 - Because air density varies with temperature and altitude changes, a main jet correction may be necessary. This chart was calculated at sea level with an air temperature of 60F.

Step #3 - Apply the multiplication factor shown to the main jet size recommended in the chart at the top of the page.

Step #4 - Your operating conditions will vary by the change of seasons. If your engine experiences performance difficulties, a review of your jetting may be necessary. Return to step #2.

Step #5 - Humidity is also a variable in determining air density. A high humidity means a lower air density of air to be consumed by combustion. Because we are generally not equipped with a way of easily reading the % of humidity present, this can be read in to this chart by adding altitude on high humidity days and subtracting altitude on in very dry climates.

Create you base line jetting for standard conditions.
If your base line tuning was at 86 degrees and a 1500' altitude with a 155 Main Jet
Calculate Base Line: 155 Main Jet / .97 = 160 Base Line Jet or specifically 159.8

To correct for local conditions of 100 degrees and 4500' altitude
Calculate Corrected Jetting: 160 Base Line Jet x .94 = 150 Main jet to use

Altitude - Feet 0' 1500' 3000' 4500' 6000'
-22F 1.04 1.03 1.01 1.00 0.98
-4F 1.03 1.02 1.00 0.99 0.97
14F 1.02 1.01 0.99 0.98 0.96
32F 1.01 1.00 0.98 0.97 0.95
50F 1.00 0.99 0.97 0.96 0.95
59F 1.00 0.99 0.97 0.96 0.94
68F 1.00 0.98 0.97 0.95 0.94
86F 0.99 0.97 0.96 0.94 0.93
104F 0.98 0.96 0.95 0.94 0.92
123F 0.97 0.96 0.94 0.93 0.92


Table of Contents
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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 -+-