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


Setting Ignition Timing for an
Aftermarket Ignition Module

Timing LED.

Most performance ignition modules have a Timing LED. This can be used for static timing and as a diagnostic aid. The LED should light up when the ignition key is turned on. The timing LED will go off when the crankshaft is rotated past TDC. During cranking the LED will blink.


For most 1984 and later models, most aftermarket ignition system installation does not require resetting the ignition timing. For earlier models where a new trigger rotor or camshaft position sensor is installed, you must reset the timing.

The TDC and advance timing marks are located on the fly-wheel and can be observed via an inspection hole (refer to the shop manual for details). Refer to Figure 1 for typical timing marks. Early Style includes most 1980 and earlier models. Late Style includes most 1981-95 models. If the shop manual is not available, remove spark plugs, turn engine until front piston is at TDC on compression stroke and identify TDC mark on the flywheel. Refer to Figure 0 and find the diagram with a matching TDC mark. Use the corresponding advance mark shown in the diagram.


If the engine will not start or runs very rough, you can use the following static timing procedure. Remove spark plugs and turn engine until TDC mark appears in observation hole. Ground spark plugs with an alligator clip so you will not shock yourself.

Turn on ignition. Loosen the standoffs holding camshaft position sensor and rotate it clockwise until timing LED goes out. The point at which LED goes off is TDC. Timing is now set approximately at TDC, which is correct for cranking conditions.

Turn off ignition and reinstall spark plugs.


This timing procedure requires that a VOES switch be connected to the ignition module. For racing applications without a VOES switch, you must ground the VOES input (purple/white wire) while setting the timing. Connect a timing light to the front cylinder. Set the ignition module advance slope switch to midrange. Run the engine at 2,400 to 2,500 RPM. Rotate camshaft position sensor until advance timing mark is centered in the observation hole. Tighten the standoffs and verify that timing has not shifted. Timing will now correspond to the curves in Figures 5 or 6.


Determine the advance you want at 2,500 RPM. Use a dial-back timing light. Set the amount of advance you want, say 35 degrees, on the dial-back timing light. Connect the dial-back timing light to the front cylinder. If the VOES is used, disconnect the VOES input (purple/white wire) while setting the timing with this procedure. Set the ignition module advance slope switch for maximum advance. Run the engine at 2,500 RPM. Rotate camshaft position sensor until TDC timing mark is centered in the observation hole. You will now have the amount of advance you dialed into the timing light. Tighten the standoffs and verify that timing has not shifted. Some dial-back timing lights are not compatible with odd firing H-D V twin engines. Most Sears units are OK. Snap-On units may not function correctly.


Did the engine run properly before installation of the ignition module? If not, remove the ignition module, reinstall the OEM ignition or another known good unit and then find and correct the original problem.

Did the ignition module function correctly before the problem occurred? If the answer is yes, did you change anything that may have affected it? Try going back to the last setup that worked OK to help isolate the problem.

If the engine will not start, or runs rough or intermittently, use the following checklist steps:


Check that timing LED lights up when ignition key is first turned on. If not, check for +12 volts on white wire to COIL+.

Check that timing LED blinks while engine is cranked. If not, camshaft position sensor or ignition module may be defective.

If the timing LED blinks, but engine will not start, recheck all wire harness connections or replace coil(s).

NOTE: Applicable to single fire mode only. Most dial-back timing lights will not work correctly in dual fire mode.

NOTE: 1996 and later models (1995 and later for export models) have a timing mark at 20 BTDC for setting the timing with the O.E. ignition module. Do not use this mark for setting the timing with the ignition module. In most cases an additional mark will remain at 35 BTDC (see Figure 7). Use this mark to set the timing with a timing light as described below.

Check for low voltage from a faulty or marginal charging system and battery.


To crank the engine and check for spark, use a KD Tools test plug or H-D tool HD-26792.

These test plugs come with an alligator clip that must be attached to frame or engine ground. Use a length of spark plug wire to connect the test plug to the coil.


Field experience has shown that popping back through the carburetor, misfiring, and intermittent failure (especially after the engine gets hot) are usually not caused by electrical problems within the ignition module. Carburetor problems, fouled spark plugs, coil failure, and loose wire harness connections are the most common culprits.

Verify that spiral core or suppression type spark plug wires and resistor spark plugs are being used.


If the tach is inoperative after installation of the ignition in single fire mode, you may require a tach adapter. Most ignition module tach output is compatible with ground sensing tachs which includes most O.E. and aftermarket tachs. Some tachs require a high voltage trigger pulse. In this case, install a Crane tach adapter P/N 8-2050.

Damage to the ignition module circuitry may have occurred if 12 volts was applied to the tach wire at any time.

Figure 0
Timing Plug Location

Figure 1
Engine TIming Marks

Early Style includes most 1980 and earlier models
Late Style includes most 1981-95 models

Figure 2
OEM Advance Curve

Figure 3
Crane HI-4/HI-4E Advance Curve Race Mode


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 -+-