31629-78 Diamondfire Spark Plugs
Fits: Big Twin | Dyna | FX | FXR | Softai…
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Specifications
- Brand
- E3 Spark Plugs
- Part Number
- 757641
- OEM Reference
- 31629-78
- Pack Quantity
- Each
- Category
- Spark Plugs
- VAT Rate
- 20%
About This Product
Upgrade your ignition system with E3 DiamondFIRE spark plugs, designed to provide a more efficient burn for your Harley-Davidson. These plugs feature a unique open ground electrode that directs the flame kernel toward the piston more effectively than standard J-wire designs. This forward-projecting electrode brings the spark closer to the air-fuel mixture, while the edge-to-edge discharge initiates a faster, stronger combustion wave. They are a great performance upgrade for Big Twin, Dyna, FX, FXR, Softail, Sportster, and Touring models, serving as a high-tech replacement for OEM part number 31629-78. By improving the combustion process, these plugs help ensure your engine runs smoother and more efficiently across the entire powerband.
Fitment
33 modelsBig Twin | Dyna | FX | FXR | Softail | Sportster | Touring
Fxr 6 models
| Brand | Year | Model |
|---|---|---|
| Harley-Davidson | 1984 | DISC GLIDE FXRDG |
| Harley-Davidson | 1982–1985 | LOW RIDER FXRS |
| Harley-Davidson | 1985 | LOW RIDER CHROME FXRC |
| Harley-Davidson | 1985 | LOW RIDER SPORT EDITION FXRS-SP |
| Harley-Davidson | 1983–1985 | SPORT GLIDE FXRT |
| Harley-Davidson | 1982–1985 | SUPER GLIDE FXR |
Softail 8 models
| Brand | Year | Model |
|---|---|---|
| Harley-Davidson | 1981–1982 | BLACKLINE FXS |
| Harley-Davidson | 1983–1985 | BREAKOUT FXSB |
| Harley-Davidson | 1984–1985 | SOFTAIL STANDARD FXST |
| Harley-Davidson | 1981–1984 | SUPER GLIDE FXE |
| Harley-Davidson | 1981–1985 | SUPER GLIDE FXEF |
| Harley-Davidson | 1981–1982 | SUPER GLIDE FXB |
| Harley-Davidson | 1983 | SUPER GLIDE FXDG |
| Harley-Davidson | 1981–1985 | WIDE GLIDE FXWG |
Sportster 1 model
| Brand | Year | Model |
|---|---|---|
| Harley-Davidson | 1981–1985 | SPORTSTER XLS |
Touring 18 models
| Brand | Year | Model |
|---|---|---|
| Harley-Davidson | 1984 | Classic Tour Glide Classic (1984) Tour Glide Classic FLT Classic |
| Harley-Davidson | 1984 | Electra Glide (1984) Electra Glide FLHT |
| Harley-Davidson | 1983–1985 | ELECTRA GLIDE CLASSIC FLHTC |
| Harley-Davidson | 1985 | ELECTRA GLIDE CLASSIC SHRINE FLHTC SHRINE |
| Harley-Davidson | 1981–1982 | ELECTRA GLIDE CLASSIC WITH SIDECAR FLHC WITH SIDECAR |
| Harley-Davidson | 1983–1985 | ELECTRA GLIDE CLASSIC WITH SIDECAR FLHTC WITH SIDECAR |
| Harley-Davidson | 1984 | ELECTRA GLIDE SPECIAL WITH SIDECAR FLHX WITH SIDECAR |
| Harley-Davidson | 1981–1984 | ELECTRA GLIDE SPORT FLHS |
| Harley-Davidson | 1981–1984 | ELECTRA GLIDE STANDARD SHRINE FLH SHRINE |
| Harley-Davidson | 1981–1982 | HERITAGE FLH-HERITAGE |
| Harley-Davidson | 1981–1982 | Heritage Classic FLHC |
| Harley-Davidson | 1981–1985 | Street Glide® FLHX |
| Harley-Davidson | 1981–1983 | TOUR GLIDE FLT |
| Harley-Davidson | 1980–1985 | TOUR GLIDE CLASSIC FLTC |
| Harley-Davidson | 1984–1985 | TOUR GLIDE CLASSIC WITH SIDECAR FLTC WITH SIDECAR |
| Harley-Davidson | 1983 | TOUR GLIDE WITH SIDECAR FLT WITH SIDECAR |
| Harley-Davidson | 1983 | TOURING ELECTRA GLIDE STANDARD FLHT |
| Harley-Davidson | 1981–1985 | TOURING REVIVAL FLH |
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