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Zündkerzen #2: Modelle 1909-1926

Zündkerzen #2: Modelle 1909-1926

  • fits all models 1909-1926
  • thread: 7/8”-18
  • thread length: 5/8 ”
  • wrench size: 15/16 ”
  • connection thread: M4
  • OEM labelling: 2
  • replaces OEM 37-09
  • USA

Spark Plug Heat Ranges

Harley spark plug heat ranges are marked by numbers, from 2 to 12. No. 2 is the hottest plug, no. 6 would then be a relatively cool plug. The coolest plug used by Harley-Davidson is marked 10R12A. Double numbers characterize multi-range plugs.

With older motors, it was not uncommon, that you achieved an optimum with plugs of two different heat ranges. Unlike the well known prejudice implied, you had to choose cooler plugs for the front and hotter plugs for the rear cylinder. On later Harley engine designs, heat distribution is balanced to such an extent that you should not have to rely on those tricks anymore.
Item №
Version
net price*
unit
Availability in warehouse Germany
Zündkerzen #2: Modelle 1909-1926
12-002
manuf. labelling: W14
$28.71
each
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* The price includes German VAT (19% or reduced rate of 7% for Books).