How to Raise the Rev Limiter on My Harley Davidsonby Don Davis
Although the parameter is commonly called the rev limiter, it is more accurately called the rpm limit, and it is a function of the electronic ignition. A stock Harley-Davidson has a limit of 5,500 revolutions per minute. Usually, on a Big Twin, about the time you hit 60 or 65 miles per hour in second gear, the engine will begin to sputter and miss. Crusty old bikers who remember mechanical points will mutter about "hitting the rev limiter," but there is no rev limiter. You change the rpm limit by installing an electronic ignition with a programmable rpm limit. Crane makes ignitions with rev limits that can be set as high as 9,900 rpm.
Remove Old Ignition
Remove the seat by loosening the Allen or Phillips screw in the fender tab on the back of the seat with an Allen wrench or a Phillips screwdriver.
Disconnect the negative battery terminal from the negative battery post with an open-end wrench.
Disconnect the spark plug wires from the coil. Remove the two remaining wires, positive and negative, from the front of the coil with a small open-end wrench.
Disconnect the plug -- called the VOES connector -- that attaches the wiring harness of the vacuum operated electrical switch to the front wiring harness.
Drill out the two rivets on the "points cover" on the lower right side of the motorcycle with an electric drill. Remove the points cover.
Loosen the two flat-head screws inside the points cover. Remove the inner cover and gasket.
Disconnect the sensor plate cable plug with needle-nose pliers. Pull the sensor plate cable through the hole at the bottom of the timing cover.
Draw a line from the V-notch on the sensor plate to the ignition housing, using a grease pencil.
Remove the two sensor plate screws and washers with a flat-head screwdriver. Remove the sensor plate.
Install New Ignition
Install a Crane Hi-4 ignition or the equivalent in place of the sensor plate. Push the new ignition cable through the hole at the bottom of the timing cover.
Align the V-notch on the Crane HI-4 ignition with the grease pencil mark on the ignition housing. Loosely attach the new ignition with the original sensor plate screws and the lock washers included with the ignition.
Route the new ignition wiring harness along the frame rails to the coil. Secure the new harness to the frame with cable ties.
Connect the black (positive) and white (negative) coil wires from the new ignition wiring harness to the positive and negative terminals on the coil, using a small open-end wrench. Reconnect the negative battery cable to the negative battery post with an open-end wrench.
Replace the seat and fasten the seat tab to the rear fender with a Phillips screwdriver or an Allen wrench. Attach the green wire in the new ignition wiring harness to the VOES connector.
Set the "mode select" dial on the new ignition to "6." Set the two rpm limiter switches to the desired setting. Set the "advance slope" dial to "6."
Set the two rpm selector dials to the desired rpm limit, divided by 100. For example, you would achieve an rpm limit of 5,500 by setting both dials to "5." For an rpm limit of 6,800, you would set the first dial to "6" and the second dial to "8."
Static Timing New Ignition
Put the Harley in the top gear. Raise it on a motorcycle jack until the rear wheel is off the ground.
Remove the front spark plug with a spark plug socket and a socket wrench. Peer into the spark plug hole.
Rotate the rear wheel and the engine until the front cylinder is at the top of its stroke. Do not move the rear wheel.
Remove the timing hole plug in the crankcase with a hex socket and socket wrench. Screw a timing view plug into the same hole in the crankcase.
Confirm that a double line, which is the top dead center timing mark, is visible in the timing view plug.
Turn on the ignition. Confirm that the LED on the new electronic ignition is illuminated.
Rotate the new ignition module by hand until the LED goes out. Tighten the sensor plate screws with a flat-head screwdriver.
Turn off the ignition. Reinstall the front spark plug.
Lower the motorcycle jack and remove. Remove the timing view plug and reinstall the timing hole plug with a hex socket and a socket wrench.
Reattach the points cover with the gasket included with the ignition kit. Secure the points cover to the ignition housing with the two self-threading screws included with the ignition, using a screwdriver.
Things You'll Need
- Programmable electronic ignition kit
- Allen wrenches
- Open-end wrenches
- Electric drill
- Drill bits
- Needle-nose pliers
- Grease pencil
- Cable ties
- Motorcycle jack
- Spark plug socket
- Socket wrench
- Hex sockets
- Timing view plug
Don Davis has been a professional writer since 1977. He has had numerous writing jobs, including writing news and features for the "Metrowest Daily News" and "Los Angeles Herald-Examiner." Davis has a Bachelor of Arts in English and history from Indiana State University.