Spark Plug - 14mm - BPR8EIX - NGK - Iridium
OEM: 6684 - NGK Iridium Spark Plug
Resistor plug for radio interference. Used with caps without resistors. The equivalent to the NGK BP8ES but with an Iridium plug with a 5k ohm resistor to reduce RFI.
If you need a hotter plug use the BPR7EIX
Adds a solid 2 HP to your 650
NGK Iridium Spark Plugs - Cheapest horsepower you can buy for your motorcycle!
While Dyno testing a problem bike (a Yamaha TX750) it was discovered using Iridium spark plugs caused the engine to gain 2 HP. Further Dyno testing on other stock and modified 650's showed the same results! The gain seems to be from improved combustion chamber flame front spread in the 650's old style combustion chamber. The same results were obtained on engines with points, factory TCI, and Boyer ignitions. We determined that the shape and position of the nose and electrode caused the gain and not any enhancement of spark. Smoothing of the dips in the power curve, increased acceleration, reduced fuel consumption and up to 4 times longer plug life can also be expected. Dyno testing performed by Heiden Tuning in Germany.
Fits the following:
Is Universal Part: No
OEM Number(s): N/A
- 1970 Yamaha XS650 XS1
- 1971 Yamaha XS650 XS1B
- 1972 Yamaha XS650 XS2
- 1976 Yamaha RD400 RD400C
- 1977 Yamaha RD400 RD400D
- 1978 Yamaha RD400 RD400E
- 1979 Yamaha RD400 RD400F