Iridium plugs yay or nay

[V_i_c_i]

I don´t like iridium plugs in our bikes. They are not better and do not have a longer life in our bikes. Just are more expensive.
Last week, I had 14 at my service. Running as a tractor. I clean fuel filters, did throttle boddies synchro and still run not perfect. Change iridium plugs that had 10 thousand kilometers for standard NGK CR8EK with 21 thousand kilometers (from my bike) and suddenly the engine run perfectly. Iridium plugs don´t like rich running and our bikes run very rich most of the time.