XJ900rk Spark Plug discrepancy

I looked through 4 different sources regarding the spark plugs specifically for the 1983 xj900rk and here's what I found:

Yamaha Owners Manual
NGK BP8ES

Haynes
NGK BPR8ES

Yamaha Service Manual
NGK BPR8ES

XJ4Ever
BP8ES

So who's right? Two for resistive and two for non-resistive plugs. XJ4Ever says that for the xj900rk model there should be a total of 5k ohms resistance between the plug wire, plug caps, and spark plugs. I couldn't locate that specific information in the other three manuals.

 

He's right, 5kohms max, so have resistor caps or resistor plugs - not both.
I don't think the xj is especially sensitive to plug types though, provided they are in the right heat range. Be careful of Chinese copies.....

 

In Canada Bpr8es
USA bp8es

 

So, I originally had resistant plugs AND caps for a total of 10k ohm resistance which is how I purchased my xj900 off the original owner. I decided to go with the non-resistant plugs as an experiment to see if there was any difference. The answer is an absolute YES! For one the bike starts RIGHT UP! Before when I hit the ignition the bike would turn over for a solid second or two before firing. It also had a lot of trouble starting when warm. Both of those issues have disappeared. Engine feels smoother and has a "crisp" response to opening up the throttle especially at higher speeds. Before, it seemed there was an ever so slight hesitation before the bike would accelerate. Next test is to see if it improved my mpg. We shall see.

 

Those wondering if my mpg has improved and the answer is a resounding YES! After a combination of canyon, city, and freeway riding I got 43mpg! The best I ever got before was 39 and I usually averaged somewhere between 35-37. I really think these numbers will improve with better tires. I'm running cheap Shinkos at the moment plus I invested in some Dynatek coils. In any case, from my experience the correct plugs and caps do make a difference.