Spark plug gap?
Seasoned HDF Member
Joined: Apr 2011
Posts: 6,185
Likes: 2,134
From: W. Texas
WP
Club Member
Joined: Aug 2008
Posts: 22,857
Likes: 17,908
From: Lafayette, Louisiana
Not quite the whole story. It depends on how the engine is set up as well as load and environmental factors.
For example in cooler weather you can run a slightly larger gap for bit more crisp response and a fraction more power. In the summer, you can't do that and your gap needs to be slightly narrower to combat detonation.
That is just one over simplified example. Things like compression, ignition timing, air fuel ratio, weight of the bike with the rider, barometric pressure, and other factors come into play that are beyond the scope of this thread.
The factory spec is the best and safest bet for most conditions. Some gains may be attainable with a larger or smaller gap, but only when you are building bleeding edge performance and account for risk / longevity.
Long ago I was into all that stuff. Needless to say my Sportster I had at the time was a fairly brisk riding little bike.
For example in cooler weather you can run a slightly larger gap for bit more crisp response and a fraction more power. In the summer, you can't do that and your gap needs to be slightly narrower to combat detonation.
That is just one over simplified example. Things like compression, ignition timing, air fuel ratio, weight of the bike with the rider, barometric pressure, and other factors come into play that are beyond the scope of this thread.
The factory spec is the best and safest bet for most conditions. Some gains may be attainable with a larger or smaller gap, but only when you are building bleeding edge performance and account for risk / longevity.
Long ago I was into all that stuff. Needless to say my Sportster I had at the time was a fairly brisk riding little bike.
Trending Topics
Club Member
Joined: Feb 2007
Posts: 16,320
Likes: 306
From: Boynton Beach, FloriDuh
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
