Resistor Type Spark Plug NGK - BPR7ES NGK Spark Plug with 14mm thread. BPR7ES. OEM: 5534. Resistor plug for radio interference. Used with caps without resistors. The equivalent to the NGK BP7ES but with a 5k ohm resistor to reduce RFI. Fits: TX650,TX650A, XS650B-K (1973-84). Part #50-6507 $2.50 Ea.

Cheap Horsepower! XS Performance NGK Iridium Spark Plugs - Cheapest horsepower for your XS you can buy! BPR8EIX - Fits: 1970-72 650's - Adds a solid 2 HP to your 650 While Dyno testing a problem bike (a TX750) it was discovered that the customer supplied Iridium spark plugs caused the engine to gain 2 HP. Further Dyno testing on other stock and modified 650s showed the same results! The gain seems to be from an 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 by Heiden Tuning. See Next listing for 73-84 models Part #50-6742 $8.50 Ea.