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Tech Tips/ DIY

Installing The Accel Stealth Supercoil

Article & Photos By: Jeff Najar

Originally Published In The January 2016 Issue Of Cycle Source Magazine

 

CSM-JAN2016.pg74_Page_1_Image_0001ACCEL Ignition is known for performance and their fl y-yellow branding provides a visual acknowledgement that you are running upgraded performance parts on your motorcycle. Recently they decided to go in a new direction, a stealth direction. During the 75th Annual Sturgis Rally I ducked into the J&P Cycles store and got the 411 from Mike Golding, Accel Ignition Product Manager, on their new Stealth SuperCoil that takes a new high-tech direction. The SuperCoil utilizes automotive-based COP technology (coil-onplug) which eliminates the external coil and plug wires by mounting the coil directly to the spark plug. A motorcycle coil is an induction coil which transforms the battery’s low 12 volts to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. When it comes to energy, more is better. The ACCEL unit delivers up to 25 % more energy than the factory ignition and allows for a more complete burn of the mixture.

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Because of emission considerations, stock bikes tend to have lean spots during acceleration and you can feel a fat spot when accelerating with a steady throttle. The higher energy minimizes these dips and can even eliminate them because it can better burn the lean mixture. Enthusiasts have reported quicker starts and improved throttle response. Modifi ed engines, especially those with higher compression ratios respond well because the increased cylinder pressure requires more energy to burn the mixture. Camshaft swaps often suffer from poor air/fuel mixture, especially at lower rpms because of an increase in overlap. Again, higher energy helps to burn the less than ideal mixture. Eliminating the plug wires creates a cleaner look and greater appeal. Relocating the coil directly on top of the plug has another signifi cant benefi t; no more lost energy because of the spark plug wires. Spark plug wires break down over time, especially carbon core wires like the stock ones. Also, anything you can do to eliminate exposed wires is a bonus when working with a late model sportster, there’s just too much wiring.

A fi nned cast aluminum cover holds the coil in place and acts as a functional heat sink to pull heat away from the cylinder head. All wiring is hidden in the fi ns of the head for a clean and wireless appearance. The SuperCoil kit is available in a natural, all black or black fi nish with polished fi ns. For our application we went with the natural in order to play off the EMD side engine covers. However, later chose to fi nish them in the engine textured black paint to add to the stealth appearance to match the existing black on the cylinder heads. For the installation I rolled into Hank Thibodeau’s Widowmaker Custom Design & Repair shop in Rougemont, NC. It’s located on the outskirts of Durham, NC and requires 10 miles of unadulterated country road carving and has everything for your enjoyment, a lake, reduced radius blind suicide corners, country stores, farms and deer. Lots of deer. As you can see by the instructions listed below, installation is a snap.

Disassembly:

Remove the seat, sparkplugs, fuel tank and disconnect the negative battery cable from the battery. Unplug the stock ignition coil and wires and completely remove them from the bike.

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Apply a small amount of the supplied blue thread lock to the (8) set screws and loosely install (2) set screws into each of the (4) cast aluminum head stud mounts.

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Place the cast aluminum head stud mounts on top of the 4 exposed head studs and fasten the set screws securely using the provided 3/32” hex key wrench.

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Install one ignition coil assembly into the cast aluminum coil cover by matching up the tabs on the coil with the slots in the coil cover. Route the coil wires through the notch on the side of the coil cover. Repeat the process. Do not tighten coil mounting screws completely at this time.

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Install the front coil and cover assembly directly onto the front spark plug and head stud mounts. NOTE: We chose to route the coil wires below the rocker boxes for an even cleaner look.

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Apply a small amount of the supplied blue thread lock to the (4) socket head cap screws. Insert the socket head cap screws through the hole in the top of the coil cover, align with threaded hole in the top of the head stud mount and fasten securely using the supplied 5/32” hex key wrench. Repeat and cover assembly. Now tighten your coil mounting screws to your covers once covers are secured.

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Connect the 4-pin plug on the supplied coil extension harness to the coil connector on the bikes wiring harness. Route the coil extension harness along the backbone of the frame so that the two coil connectors (labeled front cyl/rear cyl) drop down between the cylinders behind the throttle body. Secure the coil extension harness to the backbone of the frame using the supplied cable ties.

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Connect the coil harness from the front cylinder to the connector on the coil extension harness labeled “Front cyl”. Connect the coil harness from the rear cylinder to the connector on the coil extension harness labeled “Rear cyl”. Installation of the ACCEL Stealth SuperCoils is now complete. Reconnect your negative battery cable, reinstall your tank and seat, and fi re up your sled. Hank had this to say about the install….I feel like this is a product that is way overdue. I am glad to see ACCEL stepping up to the plate. As a builder it is a forever struggle making that all important cleaner than clean look. With this set up it just does not get any better. The install is a breeze, it can be performed by the most novice of bike mechanics. Bang for the buck, one of the best bolt on power products available.

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