31629-78 Diamondfire Spark Plugs
Fits: Big Twin | Dyna | FX | FXR | Softai…
incl. VAT
Chapter members save 15% · Sign in for member pricing
Estimated delivery: 3–15 working days
Authorised
Iron City Dealer
14-Day Returns
Easy & hassle-free
Secure Checkout
256-bit encryption
Free UK Delivery
On orders over £100
Specifications
- Brand
- E3 Spark Plugs
- Part Number
- 757641
- OEM Reference
- 31629-78
- Pack Quantity
- Each
- Category
- Spark Plugs
- VAT Rate
- 20%
About This Product
E3 DiamondFIRE spark plug. The open ground electrode projects forward into the combustion chamber to direct the flame kernel towards the piston. It uses edge-to-edge discharge instead of a standard J-wire. This replaces OEM 31629-78. It fits Big Twin, Dyna, FX, FXR, Softail, Sportster, and Touring models. Check plug reach and thread pitch against your heads before ordering.
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 | 1981–1982 | SUPER GLIDE FXB |
| Harley-Davidson | 1981–1985 | SUPER GLIDE FXEF |
| Harley-Davidson | 1981–1984 | SUPER GLIDE FXE |
| 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 |
Related Products
View all →
Harley-Davidson Accessories
Original Equipment Spark Plug
Harley-Davidson Accessories
Gold Spark Plugs
Harley-Davidson Accessories
Original Equipment Spark Plug
Harley-Davidson Accessories
Original Equipment Spark Plug
Harley-Davidson Accessories
Original Equipment Spark Plug
Zodiac (Genuine Zodiac Products)
CHROME SPARK PLUG COVERS
Accel
HP COPPER SPARK PLUGS
Accel
HP COPPER SPARK PLUGS
More from E3 Spark Plugs
View all →
Who are we? Leeds Harley-Davidson - Iron City Motorcycles
This product is fulfilled by Iron City Motorcycles, Leeds' authorised Harley-Davidson® dealer, serving the UK with a full range of Genuine Motorclothes®, dealer merchandise, and official Harley-Davidson parts & accessories — available for UK and international delivery.
From OEM Parts to retro lifestyle wear to aftermarket stockits we have what you need to keep you riding all year round.
Use our official OEM parts finder to browse our full Genuine Harley-Davidson® Parts and our associated approved aftermarket catalogues.