2.11. Spark Plugs

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The offical spark plugs for your XS

Model Plug Alternative
XS2,TX650, TX650A NGK B8ES
XS650 1975-early 1978 NGK BP7ES Champion N7Y
XS650E late 1978 cont. NGK BP7ES Champion N7Y

--herbs 20:30, 22 Jun 2005 (CEST)


Spark Plug threads

Don't torque the plugs back in tight when the case is still hot. It might strip the threads alot easier... at least that's what my mechanic told me about spark plugs in the car.

Or screw the plugs in by hand first. Let them heat in place ten to fifteen minutes to reach the same temperature as the cylinder head. Only after that tighten them into the right torque.


Choosing the Spark Plugs

I ride a XS Special '79. The last plugs what I use for a long time now are Champion N7YCC. The N7Y is the type (standard type) and 'CC' means Copper Core (between isolator and middle electrode is some copper inside, says its equalizing temperature or so). These plugs work really good, they are old, I cleaned them very often and it still starts good and dont miss a beat.

Sometimes I had bad luck with NGK (BP7ES for our bikes).

One time I had bought BPR7ES , but the 'R' means a resistor inside. Yamaha has its original spark plug boot with a resistor as well and two of them make the spark weaker. I removed this resistor from the plug boot and so having the original Yami plug boot like a 'normal' one (you can disassemble them).

I also had NGKs failing without any sign of warning before - just dies immediatly.

But I heard also negative things about Champions..

One thing I really care about is not to drop the plug or through them careless into the toolbox. They can get tiny cracks and play stupid tricks on you like failing when getting hotter and other confusing things what you dont expect that it is a faulty plug.

--herbs 07:03, 23 Jun 2005 (CEST)


NGK plugs explained

B7ES Basic spark plug

BR7ES Basic spark plug with resistor (R)

BP7ES with projected electrode, said to cope better with various engine temperature

BPR7ES projected electrode with resistor

BPR7EIX projected electrode, resistor, iridium electrode

The 'B' is the thread size (diameter) of 14 Millimeters. The recommended torque for an aluminum head is is 25-30 Nm (metric) or 18-21.6 lbs/ft for US wrenches.

The 'E' after the number is the thread reach of 19 Millimeters. The 'S' stays for the Firing End Construction, in this case 'copper core center electrode.

Spark plugs with 'R' can make trouble, especially in combination with a resistor spark plug boot.

In the catalogue of NGK Europe, issued 2006, I can still find the recommended BP7ES, the order number is 2412.

--herbs 23:29, 21 June 2007 (CEST)


Spark Plug Gaps

Model Plug Gap
XS1 & XS1B 0.024-0.028
XS2,TX650, TX650A 0.024-0.028
XS650 B 0.020-0.024
XS650 C,D,E,F,G,H 0.024-0.028


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