Breaker weight spring set. Extreme duty

Stronger than stock. For a slower advance curve used to help solve detonation issues. Less breaker weight rattle during idling and improves idling stability. Note that stronger springs may require carburetor adjustment (richer). Note: 516300 is standard replacement 516301 is heavy duty 516598 is extreme duty. Mixing different spring strengths will give additional fine-tuning options.
70-99 B.T.(excl. TC) 71-03 XL (NU). With mechanical advanced ignition
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