Fitments
70-99 Big Twin (Excl. TC); 71-03 XL Sportster (NU). With mechanical advanced ignition
Part Description
Breaker weight spring set. Heavy Duty
Stronger than stock. For a slower advance curve, used to help solve detonation (pinging) issues with compression engines or poor fuel. Also less breaker weight rattle during idling and improves idling stability. Note that stronger springs may require carburetor adjustment (richer). OEM replacement reference 32605-70 (which has standard strength springs). Note: 516300 is standard replacement, 516301 is heavy duty, 516598 is extreme duty. Mixing different spring strengths will give additional fine-tuning options.
