89 or 93 octain?

So where I live in Tennessee. Most gas stations either have 89 or 93 octain. I think yamaha recommends 91. So question is two up or two down? Would it even make a deference? Maybe the 93 premium has better additives?

Go with 93. When the factory recommends a certain octane, use it or go to the next higher. The engine's compression ratio, ignition timing, thermodynamics, etc. all calculate into the fuel recommendation. If you use a lower octane, the fuel will burn at a faster rate & cause detonation which could damage the engine. The higher octane burns slower to reduce the chance of detonation. So in a nutshell, if you use 89, you risk having detonation. The problem gets worse as the ambient temps get hotter like in Summer.

A question that plagues all of us at some time. Especially when prices go higher and higher.

I've run 87 octane with no ill effects. Many others have too.

Is it safe?

How does your bike run on it?

Higher octane does not mean "better". In fact I've read some theories that you'll get more power from lower octane than higher octane due to a more complete burn in the combustion chamber.

The higher the octane the more difficult the gas-air mixture is to ignite.

All that being said....Yamaha recommends 91 so as the owner and operator it's up to you to decide what to put in it.

Sometimes you need gas and there's nothing but 87.

Would I run 87 all the time? No. Do I occasionally use something less than 91? Yes.

It's your call.

I've run regular, mid-grade and premium and, honestly, I can't pick out any differences between them. The bike runs the same regardless. Like someone else mentioned, I also run premium during hot weather just to be on the safe side.

There is an extensive thread on this somewhere - try searching.

But the bottom line came from a petroleum engineer who said as long as there is no "knocking" you're fine. If there is "knocking" you need a higher octane gas.

+1

a cousin of mine is a chemical engineer for a very large int'l oil company. He dumbed it down for me, and basically said that octane is added to regular gasoline by blending toluene. Essentially, he said that unless your engine is high-compression, then there's no need for high octane gas. He recommended using the lowest octane rating you can get without knocking in the engine. Otherwise, the oil companies are getting richer for no good reason. Rule of thumb: use what the manufacturer recommends (if available).

gatorfan wrote:

.

But the bottom line came from a petroleum engineer who said as long as there is no "knocking" you're fine. If there is "knocking" you need a higher octane gas.

MotoJunkie wrote:

+1

Rule of thumb: use what the manufacturer recommends (if available).

+2

Well ive always used 93. I would never go with regular unless I had to. With 89 being mid grade and 93 being the highest I didn't know if it made a difference going 2 up or 2 down.
I think Ill go with safe over sorry.
Thanks for all the imput guys.

Have you read how the manual suggests we shift? If you shifted like that and gave it enough gas to keep up with traffic, you probably would need 93 octane. I run it anyway though since it only costs me about a dollar a week extra.