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Which is better over all for the longevity of your bike? And go. 91 octane is the only option I have here near my town in Indiana to go ethanol free.
 

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Which is better over all for the longevity of your bike? And go. 91 octane is the only option I have here near my town in Indiana to go ethanol free.
91 octane ethanol free won't hurt anything, it's just wasting money. You'll be good with 87 and using Sta-bil when the bike will not be ridden for a month or two. 10% Ethanol can be handled by the CBR fine, it's just storage that could become an issue.
 

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here [sydney aust] using RON [research octane number]
measurements, base petrol - 91RON [about 87 AKI or PON]
price cycle around 120c - 140c litre, currently around 140c litre,,

additive package in base petrol = 95RON [about 91AKI/PON]
costs extra 17c litre, currently around 157c litre..
another additive package = 98RON [about 94AKI/PON]
for another 7c litre,, thus base petrol + 24c litre extra..

as this is a global forum and petrol octane ratings change
measurement systems thus numbers in europe, usa, aust etc,
context is lost using a number without its measurement index,
such as RON AKI/PON etc..

for our compression ratio [10.7:1] burn rate of fuel/air mix
in combustion chamber suits faster burning 91RON or 87AKI/PON..
higher compression ratio engines designed for slow burning fuels..
in a high cr engine or super/turbocharged engine, fast burning fuel
burns before tdc thus causing pressure against upward stroke of piston
[wastes potential power plus potential knock or pre-ignition damage]..

but in our 10.7:1 cr engine fast burn rate of compressed fuel/air
works best for less compressed fuel/air, for efficient burn..

without doubt, pre-ignition is bad even catastrophic for engines..
thus high comp engines require slow burning high octane fuels..
but unless you are experiencing knock for some reason,
there is no need to use slow burning high octane fuels..

many have used straight base petrol for many thousands of miles
in long life lower combustion engines with good engine life..
so unless you specifically want to spend 17 or 24c more per litre
for an additive package that makes your petrol slower burning
there is no reason to buy/use high octane fuel in these bikes..

from point of view of performance or engine life..
 

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Which is better over all for the longevity of your bike? And go. 91 octane is the only option I have here near my town in Indiana to go ethanol free.
I use 90 PON* non-ethanol gas in all my small engine powered equipment... everything starts and runs better on non-ethanol gas, and without the concern for potential fuel system problems associated with ethanol blended fuel.

Here's another thread on the topic: http://www.cbr250.net/forum/cbr250-performance/58802-non-ethanol-gasoline-availability.html

* I live at 7500 ft. above sea level, so our pump octane numbers are typically 1 point less than what you find at lower altitudes (closer to sea level)




91 octane ethanol free won't hurt anything, it's just wasting money. You'll be good with 87 and using Sta-bil when the bike will not be ridden for a month or two. 10% Ethanol can be handled by the CBR fine, it's just storage that could become an issue.
While 3 or 4 points higher octane isn't going be detrimental to an engine that only requires 87 PON as a minimum octane, I don't see it as a waste of money using the slightly higher octane gas if it's non-ethanol, 100% gas. In other words, I'm not buying it for the higher octane, but rather for the fact that it is non-ethanol, 100% gasoline.

Also worth noting is that Honda isn't saying don't use a higher octane gas, rather what they are saying is that 87 PON is the minimum octane for this engine.

Now if you were talking about using something like 100 octane VP race gas in a stock CBR250R, the answer would be of course, that would be a complete waste of money (to the tune of about $15-20/gallon for race gas) as the engine compression ratio doesn't require anything close to that kind of octane number.
 

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Below is the last of Dave Searle's comments in the current (Nov) issue of Motorcycle Consumer News. The possible combustion drawback is worth noting.

 
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If you switched to 91 octane for 2 full tanks worth is that enough to cause a black soot build up?
91 isn't going to give you any problems. With the CBR it's a good idea to run a strong fuel system cleaner once per season anyway. It cleans the fuel system, injector, intake valves, and combustion chamber of deposits. I use Chevron Techron Concentrate at 1oz per gal every year in the 2nd tank after running the storage gas.

Something like 93 octane and above may cause more soot.

Another good thing to do with the CBR, IMO, is to run it up to redline wide-open on occasion. Make sure the oil is up to the proper level (it doesn't hold much...) and the engine is fully warm (full temp on the graph for 10 min or more) - then let 'er rip. You are helping to move out carbon deposits that build-up from low RPM running and lugging (if you ride at the low end of the rev range consistently).

Not everyone has issues with build-up from just tooling along, but some do. In general, every engine likes to be opened-up and run at WOT on occasion.
 

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If you switched to 91 octane for 2 full tanks worth is that enough to cause a black soot build up?
I doubt it very much. I actually ran 91 and 93 in my new CBR for a month or two before I looked things over and decided 87 was the way to go. (owner's manual, and this forum)! Non-ethanol gas is preferred by many. I use both depending on where I am, when traveling it sometimes is too much hassle to find. The owner's manual shows to use (PON) 86 or higher octane and shows Ethanol 10%, MTBE 15% and Methanol 5% can be used in the CBR. Anyone heard of MTBE or Methanol at the local gas station? :)
 

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I doubt it very much. I actually ran 91 and 93 in my new CBR for a month or two before I looked things over and decided 87 was the way to go. (owner's manual, and this forum)! Non-ethanol gas is preferred by many. I use both depending on where I am, when traveling it sometimes is too much hassle to find. The owner's manual shows to use (PON) 86 or higher octane and shows Ethanol 10%, MTBE 15% and Methanol 5% can be used in the CBR. Anyone heard of MTBE or Methanol at the local gas station? :)
MTBE was used for a while as an "oxygenator" in gas for a while to reduce emissions until ill effects were discovered, so it was replaced with ethanol. I remember hearing about it when I lived in the Chicago area back in the early 2000s.

I've never seen methanol added to gas.
 

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Back in the 1990's MTBE was in use many parts of the Rocky Mountain West. I lived in Minnesota at the time and I recall making snowmobiling trips out to Colorado in late winter/early spring, and noticing the exhaust from vehicles had a peculiar, rather noxious smell. It was very noticeable when driving through the Denver area, and I remember thinking at the time that those vehicle emissions can't be good.

I must have a fairly sensitive sense of smell when it comes to fuel... I can discern the difference between an engine burning an E10 blend, and one that is running on 100% gasoline.
 

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dave searles comment on 87pon/low compression
and clean ignition does not apply to our 10.7:1 cr..
owner manual specifies; "Your motorcycle is designed
to use research octane number (RON) 91 or higher."

while most modern road motorcycles have 10:1 to 12:1 cr,
royal enfield bullet '500' single for eg, has 8.5:1 cr
 

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As shisoshin points out, the key words in the CBR250R Owner's Manual regarding minimum recommended fuel octane are "or higher".
 

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Seems that an aspect of this E10 vs. Non-ethanol gas debate which is often overlooked, is frequency of use.

As Honda states in the O/M, the fuel system is designed & manufactured using materials to tolerate E10. I'd tend to think that this is also based on a bike that is being operated on a regular basis. In other words, if your 250R is a daily rider and you're going through the better part of a tank of fuel every week, you're probably less likely to have issues as a result of using E10 during the riding season.

In my case, none of my bikes (or any of the other small engine equipment I own) are used on a regular or daily basis, so for me using only non-ethanol gasoline year round is a no brainer.
 

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Gas with ethanol can experience what is called "phase separation" (PetroClear - Understanding the Dangers of Phase Separation in Ethanol Blends).

Basically holding excessive amounts of water and breaking down into 2 layers. That can happen at any time during production, transportation, or storage.

That means you can get "bad" gas right at the station and it will not last as long as gas without ethanol.
 

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storage tanks have different level meters at bottom
for measuring levels of ethanol blend fuels, in inches,
to measure the fuel level, above the water level..

ie, beyond pr etc, industry recognises that water
will/does get into storage tanks..

before you start pumping into your, tank..
 
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