spark plug change interval
 

at 85000 miles, I noticed there was more vibes from the engine. I was puzzled as the fuel consumption & performance were the same.

Tried two different tankful of fuel with no change.

I thought it was my imagination but as a last resort, I had the plug changed (CR7). The one that came out looked very good so I looked like a waste of time but...

The engine has become smooth again (more like sewing machine than a tractor) and I am a happy boy.

How often do you guys change your spark plug. I also read some found CR8 (colder plug) make the engine run better. Any ideas as to why??

spark plug change
 

How often do you guys change your spark plug. I also read some found CR8 (colder plug) make the engine run better. Any ideas as to why??[/QUOTE]

I had a similar improvement when I changed to an iridium spark plug after about 4000 miles.

I got the best improvement from a CR8EIX Iridium plug. The standard plug, CR7 and its Iridium equivalent (CR7EIX) both made the bike feel lumpy, and I originally thought it was a problem with fake NGK plugs.

I think it may have to do with the power commander / stage 3 making the engine hotter? So a higher rated plug is required for me?

Not sure of the exact combustion science, but it works for me.

It'll only cost you a few quid to try it out.