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The stock coils are prone to leaking so much spark that some riders have observed large arcing from their coils to the frame or tank on a dark night. Yikes! As a result, many owners have wrapped their coils with electrician's tape--an adequate, if un-elegant, solution.
Idiot Disclaimer: Do not run your engine in an enclosed space to achieve darkness. Do not touch coils or sparkplug wires while the engine is running.
I wrapped my coils with electrical tape several years ago, and it did seem to help smooth the idle a bit. But then I read that many owners were tracing various engine difficulties--especially plug fouling and carbon build-up--to sparkplug wire issues. It was discovered that the stock wires have excessively high electrical resistance. In fact, owners that modified their stock plug wires reported easier starting, smoother idle, and less carbon build-up. The stock sparkplug wires are built right into the coils, so you can't replace the the wires without also replacing the coils. When Nemesis Racing announced their introduction of high performance coils and plug wires, I decided it was time to replace mine. There are two, primary, options for aftermarket coils for the Road Star:
- Dynatech, (Dyna Performance Electronics, Glendora, CA)
- Nemesis Racing, (Nemesis Racing, firstname.lastname@example.org, Australia, or email@example.com in North America.)
I opted for the Nemesis ones, as I have had excellent results with their other products, and, though I am not an electrical guru, I knew that matching component specs was important. Here's what Joel (Odo) Parker (Road Star Clinic author, and professional Yamaha mechanic) has to say:
"Our coils are rated at 1.53 ~ 2.07 ohm resistance, (99 to 03's), so, getting that rating right in there with how our systems work, is essential. The Dyna coils for our R*'s are 2.2 ohms, (A little too high). The Nemesis coils are 1.5 ohms, ('JUUUSSSTTT' right. :-)). More spark for the system.”