Fuel economy issue

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Jan 24, 2011 | 06:17 PM

#41

xricer

Senior Member

Joined: Apr 2008

Posts: 162

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From: SW Ontario, Canada

I swear that on my tail section (subframe) there is a sticker that says 91 octane minimum, am I wrong? (02f4i)

Jan 25, 2011 | 06:54 AM

#42

RoadiJeff

Senior Member & Lord of The Man Cave

Joined: Dec 2009

Posts: 1,293

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From: St. Louis, MO

Quote:

Originally Posted by Xander F4i

i know that one time i had to get gas the station only had 92. (I also realize the owner's manual says it's designed for 87). so, i figured 92 shouldn't make any noticeable difference, but the bike seemed to run really rough on it, so I've been afraid to run 87.

Some years ago I did a study over several months while experimenting with different octanes in my old car. Although the owner's manual stated to use 87 octane I ran with 87, 91 and 93 for 3 tankfuls each. At the end of the study there was no noticeable difference in fuel economy between the 87 and 91. However, when I ran 93 octane my fuel economy dropped 2 mpg.

I've read that unless you've done engine mods to change the timing or compression ratio your engine runs best at whatever octane the engineers designed it to run on. I know there's sometimes the placebo effect when using higher octane. This was an automotive study but I suspect the same conclusions could be applied to internal combustion motorcycle engines.