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Discussion Starter · #1 · (Edited)
I've watched a number of videos on odysee.com, (an alternative to youtube, just as rumble.com is) that have been posted by Scott Kerekes, who is known as SCOOTER TRAMP SCOTTY.
His present engine is basically, a stock Evo at 80 cubic inches.
He makes a point of saying it's a low compression engine that runs on regular grade gasoline.
If we leave present era SPORTSTERS out of this thread for simplicity, (I understand SPORTSTERS are EVOLUTION engines to this day) when did the Big Twin engines transition to higher compression that call for higher grade gasoline?
Thanks for the info!
 

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My '07 96 inch runs fine on 87. Wouldn't say it runs great, but for a couple hundred miles I really couldn't see any difference from the 89 or higher that I usually put in it.
 

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Knuckleheads
 

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Discussion Starter · #4 ·
I appreciate the info on the '07 with 96 cubes! As to the "Knuckleheads", Thanks.
[I should have been more clear that I was asking about later Evos and Twin Cams.]
 

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Sportsters, while being Evo engines (or at least, used to be), the Sportster Evo is different than a big twin Evo.

Stock big twin Evo could run on 87 (specified in the manual), Sportster could not. Anything older than that could run 87 when stock. Maybe the early 88" twin cams could? Not sure.

But big twin Evo owner's manual definitely says designed to run on 87 octane. This is just considering what the owner's manual specifies, not what's best. Sportsters have specification of minimum 91 octane (at least up to 2003).
 
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Count your blessings if you had a 96 that ran on 87. My 11 Ultra had a 96 and I got stuck out west in a little burg that didn't have 92 oct. anywhere in the area. Had to settle for 89 which was THEIR premium grade. Engine clattered all the way to the coast (except when running downhill) where I found some real premium and the clattering stopped.
 
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