Breaker weight spring set. Extreme duty

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.

Fits: > 70-99 B.T.(excl. TC); 71-03 XL (NU). With mechanical advanced ignition