Many people modify their Harley-Davidson engines—and find the results disappointing. What they might not know—and what this book teaches—is that emphasizing horsepower over torque, the usual approach, makes for a difficult ride. Author Bill Rook has spent decades perfecting the art of building torque-monster V-twin Harley engines. Here he brings that experience to bear, guiding motorcycle enthusiasts through the modifications that make a bike not just fast but comfortable to ride. With clear, step-by-step instructions, his book shows readers how to get high performance out of their Harleys—and enjoy them, too.
Many people emphasize horsepower over torque when modifying their Harley-Davidson engines, making for a difficult ride. Here the author guides motorcycle enthusiasts through the modifications that will make their ride both fast and comfortable.
Table of contents
Introduction
Chapter 1: Power Theory 101
The Internal Combustion Engine
Torque and Horsepower
Torque
Horsepower
More Torque
Consider this Extreme Example of Torque
Horsepower and the Facts of Life
The V-Rod and Torque
Before We Get Started, There are Two Important Things to Consider
Peak Volumetric Efficiency
TC-88 Compression and Cylinder Head Information
Squish Bands or Quench Area
Aluminum Head Squish Bands
Squish Bands for Iron Cylinders and Heads
Compression Ratios
Checking Compression with a Leakdown Tester
Ignition Advance
Ignition Trivia
Maximum Twisting Force
Average Piston Speed
Pistons
Stock Rod-to-Stroke Ratios
Crankcase Breathers
Head Porting
Is Bigger Really Better?
Approximate Maximum Intake Flow Values with Stock Unmodified Heads
Stock Head Flow Numbers
What Oil Should I Run in My Harley?
Synthetic Oil Recommendations
Synthetic Oil and Gaskets
Got Cold Oil?
Warm-Up Procedures
Example of Proper Warm-Up Procedures in the Real World
Oil Changes
Snake Oil
What Kind of Harley to Modify?
Things to Consider about Modifications
Choosing a Bike to Modify
Considering a Used Modified Bike?
Performance Motor Kits—Go Fast in a Box
Kit Suggestions
Picking a Kit
It’s All in the Tuning
Kit Summary
Chapter 2: Tuning Intake and Exhaust Tuning
Tuning the Length of Your Intake System to the Induction Tract Pulse
Induction Track Pulse Formula
Exhaust Tract Tuning
Rules on Exhaust Systems
Exhaust Pipe Bluing and Anti-Reversion (AR) Pipes
Tuning Headers
Exhaust-Gas Port Velocity
Exhaust Pipe Insulating
Pulse Waves
Let’s Review What We’ve Learned
Chapter 3: About Camshafts . . .
The Most Important Question to Ask Yourself about Cams Is . . .
Here Are My 26 General Cam Rules to Avoid Screwing Up
Cam Lobe Height
Cam Valve Lift
Valve Lift Limitations
Intake Valve Openings
Advanced or Retarded Cam Timing
Cam Overlap
Lobe Separation Angle (LSA)
Changing Cams
Gear Drive Twin-Cam Cams
Lifter Noise Tip
Other Twin Cam Upgrades
Other Twin Cam Considerations
Twin Cams Short Pushrod Tubes
Chapter 4: Mixing Air and Fuel
Overview
Jetting for Altitude
Effects of Barometric Pressure
Changes in Air Temperature
Air/Fuel Ratios and Brake-Specific Fuel Consumption (BSFC)
Air/Fuel Ratio Meter
Tuning with an Air/Fuel Ratio Meter
Personal Experience
Sensor Warning
Electronic Fuel Injection (EFI)
How Does EFI Work?
Open-Loop System
Closed-Loop System
The New Delphi EFI
So What Can I Expect?
What Are the Experts Doing with This?
What About the Stock EFI and Big Motors?
EFI and Exhaust Systems
Power Commander
To Sum Up EFI
Nitrous Oxide—It’s No Laughing Matter
About Nitrous Oxide . . .
Supercharger and Turbocharger
Ram Air Induction
Carburetor Jet Air Bleeds
And Now, a Bit More Detail . . .
Emulsion Tubes
Power Tubes
S&S Super E and G and Other Butterfly-Style Carburetors Tuning Notes
S&S Super E Jetting—My Recommendations
S&S Intermediate Jet
S&S Main Jet
S&S Adjustable Air Bleed
Jet Conversion Formula
ThunderJets (T-Jets)
Carburetor Flow Rates
To Sum Things Up on Size
Stock 40-Millimeter Keihin Constant-Velocity Carburetor
My Personal-Usage Recommendations for the Keihin 40-Millimeter Carb
Stock Jettings
Keihin Idle Mixture Screw
Keihin Jetting Recommendations
CV Diagnostic Tips
More Diagnostic Tips
Stock Harley Air Cleaners
Jet Kits for CV Carbs
More Keihin CV Jetting Notes and Tips
The CV Jet Needle Problem
CV Jet Needle Fix
Gas Mileage
A Closing Thought on Tuning
A Closing Thought on Jetting
Let’s Discuss Where I’m Going with This…
Air/Fuel Ratio Graphs
Okay, Let’s Go from Not Bad to Flat-Out Ugly
Mystery Fuel Curve Solved
Chapter 5: Gearing
The Stock Gearing Problem
A Note from Jerry Branch
Stock Dyna Gearing, Model Year 2000
How to Determine Your Gear Ratio
Lesson Learned—Automatic Primary Chain Adjusters
When the Rubber Meets the Asphalt
Clutch Tip
Tip on Buying Parts from Harley
Stock Shocks
Tire Tip
Adjusting Rear Drive Belts
Remember the Old Chain Rule?
Chapter 6: Dynamometers
Why You Need Them
Absorption Dynos
Inertia Dynos
Avoiding Dyno Disasters
Dyno Testing
Tricks They Might Use to Manipulate the Numbers
The Throttle Trick
The Gear Trick
Playing God with the Weather Trick
Before Dyno Testing
Things to Do at the Dyno
Things to Check at the Time of the Run
Summary
Chapter 7: Compression 101
Squeezing Air and Fuel Together
Mechanical Compression
Corrected Compression
Static Compression
Effective Compression
What is Camshaft Percentage?
Cranking Compression
Dynamic Compression
Leakdown Tester
Compression Review
As a Side Note
Compression, Cams, and Reversion
Intake Reversion Defined
Reversion Pros and Cons for Heavy and Light Bikes
Computer-Based Simulator Programs
Airflow Requirements
Chapter 8: Do It Yourself at Home Head Fix
Low-Budget Motor Recipes for 883 Sportster and the Twin Cam 88
Stock Head Restrictions
Hemis and Hemispherical-Shaped Combustion Chambers
The Hemi’s Problems
Head Considerations
Low-Budget Home Head Modification 101
Required Tools
Here’s How to Do It
Here's a Valve Performance Tip: Back Cutting the Valve Face
A Quick Note on Inspecting Parts
Chapter 9: Low-Tech, Bare-Bones 883 Sportster Fix
Quick and Cheap
The Parts List
Top-End Parts Breakdown
That's Everything You Need for the 883 Conversion
Cam Considerations
Dyno Power Results
Sportster Compression Ratios
Things to Check on All Motors
Gaskets: To Glue or Not to Glue?
Sealing Head Gaskets
Loctite—the Binding Blood
Loctite Tips
Torque Wrenches—A Must
Chapter 10: Twin Cam Motor Recipe
My Personal Perspective on the New Twin Cam Motors
Fast-Forward to 1999
Motor Recipe: Low-Tech, Bare-Bones Twin Cam 88 Fix
Let’s See What We Have to Work with—the Good and the Bad
Stage I
Parts List
Stage II
Parts list
Stage III
Cam Tip Time
Parts List
Cam Bearings Tip
Two Twin-Cam Cams Analyzed
Stage III Conclusion
Stage IV: the Final Frontier
Twin Cam Head Considerations
Required Airflow
Carburetors
Carburetor Rules
Twin-Cam Cams Compared
Combustion Chamber Volumes
Proper Motor Design Steps
Twin Cams Oil Pump Failures
Twin Cam Ignition Modules
Twin Cam Dyno Test Information
Twin Cam Head Flow Information
Chapter 11: Magnetos: Magic or Madness, and a Bunch of Other Stuff
Introduction
Electricity
Current
Voltage
Amperage
Electrical Workload
Workload Example
Direct Current (DC)
DC Trivia
Alternating Current (AC)
Diode
Conductor and Conductance
Capacitance, Capacitors, and Condensers
Resistance
Inductance
Magnetos: Theory of Operation
The Magneto’s Magic
Coils Illustrated
Peak Magnetic Flux
Important Note on Magneto Coils
Points
Condensers
Testing Condensers
Magneto Magnets
Fairbanks Morse Parts and Servicing
Other Contacts for Parts
Testing Double Secondary Coils
Notes on Magneto Parts
Stock H-D Coils
Coil Specifications
Stock H-D Condenser
Morris Condenser
Factory Racing Condenser
Fairbanks Morse Condenser Chart
Troubleshooting Tips
Ignition Systems and Radio Frequency Energy
Spark Plug Wires
Leakage and Spiral-Core Wires
Spiral-Core Wire Review
Troubleshooting Plug Wires
Spark Plugs
Timing
Temperature
Adjustable Magneto Advance
Duel-Plug Heads
Intake Manifold Leaks
I've Checked Everything, but Something is Still Not Right
Single-Fire Magnetos
How Reliable is this Module? How Long Will it Last?
It Sounds Like Magic, so How Does it Work?
Make Your Own Single-Fire Module
Here’s How You Connect It
Running Dual Modules
Here's What It Will Look Like
A Few Last Words on Magnetos
Magneto parts
Chapter 12: Tools
Specialty Tools
Torque Wrench Direction Reverser
Using Extensions on Torque Wrenches
Cylinder Head Wrench
Homemade Leakdown Tester
Here’s How I Made It
Keihin Carburetor Idle Mixture Tool
Soldering Tool
Clutch Locking Tool
Primary Locking Tool
Clutch Spring Compression Tool
Transmission Mainshaft Tool
Compensating Sprocket Nut Wrench
Primary Cover Plug Tools
Other Useful Tools
Allen and Torx Sockets
Universal Joint Socket Fix
Rear-Wheel Alignment Tool
Intake Manifold Tool
Syringes
Indexing Washers
Spark Plug Cleaner
Twin Cam Oil Filter Wrench
Closing the Toobox … a Thought
Appendix
Magneto Parts Breakdown
Removing Magneto Key Locks
Illustrated Racing Magneto