The book recommends the use of NGK 9EH-9 plug in the '99 model F4. I have converted this to track bike and am keen to know what would be the best range of plug to use for this purpose?
The 9EH-9 plug is designed for long durability, so I am not sure how it will work out on the track!

Any suggestions?

 

Perhaps the F4 forum would know more then the F4i forum but I'd stick with the oem plug. Never heard about it being designed for longevity considering they are replaced every 16,000 miles. Thats a really, really short spark plug life.