Accel Single/Dual Fire Ignition Module
Description
ACCEL Ignition Model 35496 is intended for use with Harley-Davidson Evolution type motorcycle engines. The Model 35496 replaces the original equipment (OE) electronic ignition system on 1978-99 models. The unit mounts in the gear case cover and uses the standard H-D® timing rotor. It can also be used on earlier models with breaker points and mechanical advance.
The Model 35496 offers adjustable advance, adjustable RPM limit settings in 100 RPM increments, and switch selectable single or dual fire modes. Single fire mode improves starting, reduces the occurrence of backfiring at low RPM, and improves power at high RPM. A red status LED flashes when the engine reaches top dead center (TDC) and allows easy static timing. The status LED also provides diagnostic information. A green VOES LED illuminates when the VOES (vacuum switch) input is active.
Avoiding Heat Related Failures
Heat kills electronics. The Model 35496 uses electronic devices rated for operation at 105 deg C (221 deg F), the highest rating available. The unit can tolerate somewhat higher temperatures, but exposure to temperatures above 125 deg C (257 deg F) will greatly reduce life expectancy. We sometimes see problematic applications where several module failures have occurred. The failure mode is a classic thermal intermittent where the module stops firing one cylinder when it gets hot. We have found that these problematic applications share one or more of the following characteristics:
- VOES switch removed or non-functional. All street driven engines require vacuum advance. Without vacuum advance at idle and part throttle, thermodynamic efficiency is reduced and engine temperatures increase significantly.
- Improper carburetor jetting resulting in lean air/fuel ratio (AFR). A lean AFR will cause the engine to run very hot. All performance engine modifications necessitate carburetor rejetting. Carburetors are never correctly jetted out-of-the-box. The only practical means of correctly jetting a carburetor is to test the motorcycle on a chassis dyno equipped with an exhaust gas sniffer.
- Lack of an oil cooler on a 95 CID or larger engine.
- Exhaust pipe without heat shield in close proximity to the nose cone. If any of the above applies to your application, the Model 35496 may be exposed to excessive temperatures resulting in reduced life expectancy. Use an infrared thermometer to check the module temperature.
