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


Cylinder Heads
installation, modifications and porting

Performance and Technical information on cylinder heads, valves, valve sizes, valve springs, port size, port shapes and compression ratios for Harley-Davidson motorcycles.

Cylinder Heads

hd_head_combustion_chamber00.jpg (16346 bytes)
This what a stock EVOLUTION combustion chamber looks like with stock sized valves. This head came off an 80 CID engine that produced 101 horsepower.

Contrary to popular myth, serious power can be made with stock Harley-Davidson heads without reshaping the combustion chambers, polishing the ports and combustion chamber, using a larger intake valves or making the ports larger. A good 'street or pocket' port  consists of improving the air flow around the valve seat and valve guide areas of the head. A good 5 angle valve job is performed, and the heads are ready to go on the bike. Heads reworked in this manner should see increased air flow over stock heads of 10-15%. That should be more than enough to create a 90 HP engine with the proper pistons, carburetor, camshaft, exhaust system and ignition system.

What goes into a good set of performance heads? All you need is the proper port shape, the proper valve sizes to allow good air flow, the right springs to keep the valves properly seated and the right compression ratio for the power you want.

Proper installation of the cylinder heads is critical to engine life and performance. Did you know there are two different ways to install the cylinder heads on a Harley-Davidson engine? Instruction are provided for both ways.

To learn more about cylinder heads, port design, valve sizes, compression rations, installing a new set of heads and more,  just click on the item in the menu you want to know about.

Cylinder Head Installation
Cylinder Head Bolt Torque Values
Compression Ratios
Cylinder Head Port Design
Cylinder Head Valve Sizes
Cylinder Head and Piston assembly
Rocker Box
Bolt Torque Values


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 -+-