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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


Sportster Detonation

Performance and Technical information on ignition for
Harley-Davidson Sportster motorcycles.

Solving Detonation on Sportster Engines

Detonation in Sportster engines is a very common complaint. From stock 883 through extensively modified 1200's, the Sportster engine is prone to detonation. Can the problem be eliminated or minimized?

The detonation problem with Sportster engines seems to stem from an improper advance curve. In Buzz Buzzelli's book on Sportster Performance, he describes the problem in detail. It seems that the Sportster engine runs best when full advance is reached at 3200 RPMs. The advance curve in various HD ignition modules gives full advance around 2500 RPMs. This leaves about 700 RPMs where the engine could be over advanced, leading to mild detonation. The recommended ignition settings and advance curve for Stock, Stage I and II engines (883 and 1200) is:

Initial advance 10-12 degrees
22-25 degrees advance at 2000 RPMs
28-30 degrees (full) advance at 3200 RPMs (recommend 28)

Not even the Screamin' Eagle ignition modules completely meet these requirements. The only ignitions that are able meet this criteria are some of the new programmable ignition systems like the V-Thunder. It must be noted that the programmable ignitions require a computer in order to modify the advance curve to meet Sportster requirements

Although the Screamin' Eagle ignition module does not exactly meet the advance requirements as recommended in Buzzelli's book, he does indicate that the SE Racing Module for Sportster and the early Sportster module (part number 32410-87) are acceptable in most engines.

Stock timing specifications for Sportster Evolution engines

The 883 engine is set for 35 degrees of total advance.
The 1200 engine is set for 28 degrees of total advance.


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 -+-