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Discussion Starter #1
Owners manual suggests 87 minimum (never seen less than 87 at a station anyway). Seller said that he was told 91 is what he should use at all times.

Rumor has it that the higher octanes can cause build up in the engine if not required, I'm no expert, not sure if there's any truth there, or if it applies in my case.

Should I go with 87? Or bump up to 89/91? If 87 is what they suggest at a minimum, I might as well go with 87, eh?
 

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2007 Yamaha Road Star Silverado 1700
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The lowest you can find. The 500 is not a high performance, high compression ratio engine and doesn't need high octane fuel.
 

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87

If the manual says 87, I think I would use 87. In fact everything I own runs on 87.
A study of flame travel in the combustion chamber, would reveal more info on the choice of octane, and cam timing, and ignition timing, and cooling systems, and a bunch of stuff.

But if it runs fine on 87, you can skip the research.

Unkle Crusty*
 

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Ace Tuner
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An easy way to tell, keep a watch on the spark plugs.
If you see pink or reddish colors on the insulator, too hot in the combustion chamber and probably insufficient octane.
(Assuming a properly tuned/maintained stock motor that has NOT been left idling for long periods of time).

91 octane will not cause any problems. The previous owner was most likely told to run 91 as if to error on the side of caution..........
You would hope the owners manual would be right about fuel requirements. You should be safe with 87.

I use Premium fuel, but I'm overly cautious when it comes to my machine.
 

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Mine calls for 87 but i usually run Shell Silver (89) mainly because it is only (up to) 5% ethanol. But this time of year when it be sitting more than riding i switch to Shell 91 due to no ethanol.
 

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Inrun 87 in my Vulcan 500 (same engine, tuned differently). I tried higher octanes, but saw no difference in performance ( actually got worse gas milage on 91). I think you would just be wasting money on the premium fuels on this bike.
 

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Discussion Starter #7
Thanks for the replies everyone. I see no reason to use higher than 87, unless the spark plugs show signs mentioned by the user above.

Thanks for the replies.
 
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