Some of the bigger names like Mobil, Exxon, Shell add in some detergents to make it more marketable to those who don't need it. But otherwise no there isn't. And actually some detergents will foul plugs faster then need be. The best thing to do is use the octane the factory recommends and to use a total fuel system cleaner with each oil change. Much cheaper and better in the long run.

Here is something I learned while in a mechanics class: On modern engines with sophisticated engine management systems, the engine
can operate efficiently on fuels of a wider range of octane rating, but there
remains an optimum octane for the engine under specific driving conditions.
Older cars without such systems are more restricted in their choice of fuel,
as the engine can not automatically adjust to accommodate lower octane fuel.
Because knock is so destructive, owners of older cars must use fuel that will
not knock under the most demanding conditions they encounter, and must
continue to use that fuel, even if they only occasionally require the octane.

If you are already using the proper octane fuel, you will not obtain more
power from higher octane fuels. The engine will be already operating at
optimum settings, and a higher octane should have no effect on the management
system. Your driveability and fuel economy will remain the same. The higher
octane fuel costs more, so you are just throwing money away. If you are
already using a fuel with an octane rating slightly below the optimum, then
using a higher octane fuel will cause the engine management system to move to
the optimum settings, possibly resulting in both increased power and improved
fuel economy. You may be able to change octanes between seasons ( reduce
octane in winter ) to obtain the most cost-effective fuel without loss of
driveability.

No, the best thing to do is scan for KR. If you're getting no KR with 87, then going to 89 is a waste. If you have KR with 87, and you go to 89 and get no KR, then going to 91+ is a waste. You can't go with what the factory recommends unless your car is the way it came from the factory. Modded cars need to be scanned to tell what you need. My .02

Hercman,

I did a search and found out that the difference between RON and the (R+M)/2 is 1.0454 to 1 (RON to R+M/2). So your bike requires 91 * 0.9565 = 87.04 R+M/2 gasoline. So regular 87 should be just fine for your bike. Hope this helps. Here is the link that I got the information from:

http://www.asmaracing.com/TracksideSupport.html

Thanks Caesar.

As for 99GT2dr,

Not everyone has access to scan for KR and not everyone has a modded car. I was giving general advice that applies to most vehicles.

i've got a scanner coming in about a week or so hopefully.... im eager to check out the knock retard!!!!!!!!