Response to the last 3 posts...
Thanks.
Long and short... I don't know but I like to learn.
Igofar identified that my plugs were wrong, I believe because of the lack of collar.
Perhaps they are genuine NGK, perhaps they are knock offs. According to the chart Igofar posted, they don't seem like knock offs. I don't know and likely never will.
Iridium versus standard... In the multitudes of readings I've done on the subject, there is a consistent description of a "more powerful spark" leading to "greater explosion propagation" (or descriptions similar to this). Since I am not a hydrocarbon or air atom inside the combustion chamber, I cannot confirm or deny any of this, but have to gather information from people more knowledgeable and experienced than I on the matter.
Continuing, it seems consistently stated that iridium plugs can give an easier start up, smoother idle, and quicker power transition when throttling up. Some claim (but I have not seen any comparisons) that fuel economy can improve. If indeed the spark is better quality which leads to more powerful explosion and more complete combustion, then it logically follows that fuel economy will be improved.
When we replaced the spark plugs in my Toyota Venza, I got an immediate MEASUREABLE (not psychological) improvement in fuel economy compared to the previous standard plugs. From 15.9 l/100km to 14.7 l/100km. The gas savings paid for the plugs and cost of installation in a year. Was this because the old plugs were on their last legs, or because the iridium truly are better, or a bit of both...?? None of you, nor I, will be able to truly compare.
But, what I can do pretty easily, is run my motorbike with different plugs - same route same speed - and measure my fuel economy. I am also a lad gifted (and cursed) with extremely acute senses. So while I'm aware that one needs to be careful for psychological expectations leading to noticing "performance improvements" which aren't truly there, I should be able to notice differences in idle and throttle-on response if there are any to be noticed.
I'm actually pretty excited to try the bike with different sets of plugs (hopefully no counterfeit plugs) to measure and "listen" with my acute senses to see if indeed there are any differences, or no differences. Of course, I will be glad to share my results with all of my st1300 riding brethren on this forum.
And for my Shadow brother, Andrew, here's a repost of an interesting link about spark plugs that I posted earlier in this thread.
And here's another interesting and informative article I read today.
God bless you all!! No matter whether you ride with a collar, or not, rubber side down!!
Cheers!