I’m looking for some advice on fuel choice for my 1992 Honda CBR600F2. My bike was originally designed for 87 octane, but I’ve made several modifications and am wondering if it’s worth switching to 93 octane.



Here are the current mods on my bike

Jet Kit: 42 pilot jets and 145 main jets

(Carbs were synced and air to fuel ratio adjusted as well)

K&N HA-6091 Air Filter

Vance & Hines 4-into-1 Exhaust

Aluminum Radiator for improved cooling



I’ve been using 87 octane and getting around 34 mpg with a mix of hard riding and varied conditions. However, I’m considering switching to 93 octane and have noticed it might slightly lower my mpg to around 32.



1. Given the modifications, would you recommend using 93 octane for better performance or is 87 octane still adequate?

2. Has anyone experienced significant performance improvements or differences in fuel efficiency when switching to 93 octane with similar mods?



Thanks in advance for your insights!

 

Mine is a 1993 F2 in the UK, I have always been advised that the octane does not matter but the ethanol content does and to always use E5 rather than E10 fuel (which, coincidentally, is the higher octane).

 

The bike is designed to run on 87. Upping the octane will just empty your wallet.
However, @Ed Harris stated, go for the lowest ethanol rating as possible. I'm fortunate in that I live in an area where ethanol free gas is available. It's expensive but worth it in some cases.

 

@hamlin6 even with the upgrades I should still run 87?

 

I don't think so. But the best way to know for sure is to run through a few tanks of fuel with each octane and record the metrics for which you are concerned. An ultimate way is to reserve time on a dyno and let them measure everything. They can empirically answer the questions for you.