[NMKawierider]

Then you have this industry standard for carbed vehicles but with the highlighted statement that EFI controlled vehicles with the same compression ratios use 5-7 points less. All I know is I can get 87,89 & 91 octane fuels here and all have ethanol..and per this chart with the deductions, this 10.3:1 EFI engine should use better then 90 and less then 93...so it gets the 91. I have tried 87 and I don't know if my altitude (5400-12,000) has anything to do with it but it doesn't run as well and..I think I hear it pinging...maybe just me though but it doesn't run as well for sure.

[brian smith]

one thing you need to take into consideration is the ethenol it is alcohol and when you use alcohol in a engine it run cooler than regular gas so less octane wont hurt because it is not burning as hot just something to consider and think about.

[MarAgt]

Well, lots of good info.  Thanks!

[doug80638]

NMKawierider:

That's really odd, since higher elevation usually results in lower compression ratios and thus, lower octane requirements. But if higher octane works better for you, then so be it.

There are so many more variables that go into determining octane requirements than just compression, especially in modern engines which can run well on 87 with compressions of 10.1. But I do like the idea of trying a higher octane fuel just to see if there is a difference in performance.

My only concern would be if higher octane fuel than recommended is eliminating pinging, that there could be carbon buildup that is helping to ignite the fuel prematurely or the valve settings are off.
 

[NMKawierider]

NMKawierider:

That's really odd, since higher elevation usually results in lower compression ratios and thus, lower octane requirements. But if higher octane works better for you, then so be it.

There are so many more variables that go into determining octane requirements than just compression, especially in modern engines which can run well on 87 with compressions of 10.1. But I do like the idea of trying a higher octane fuel just to see if there is a difference in performance.

My only concern would be if higher octane fuel than recommended is eliminating pinging, that there could be carbon buildup that is helping to ignite the fuel prematurely or the valve settings are off.

Here's another observation I have made here....and may be true at other elevations. Outside air temperature...and its effect on air density and possibly combustion temperature. I notice in the winter to get the same performance...and millage on my vehicles, I need to drop a grade of fuel to 89 or even 87 octane depending on how cold it is. The colder, the lower octane I need to use. Maybe that's just some common sense but it is noticeable.   

[REDRIDER]

You will make less power running higher than required octane as you are not getting a complete burn and the explosion is not as good as it could be. One reason i laugh when people go to the race track in thier daily driver and throw race fuel in the thing thinking its gonna make it faster, nope sorry.  If you have an engine running on the edge the ambient air temp may have a factor like nmk notices when hot you may need a little higher octane to keep from preignition then cold temps you could run lower,  though i don't know if it would be noticeable.  When you squeeze air it gets hot,  so if the air starts at 0 degrees it may not get close to combustion as quickly as air temp starting a 90 degrees.  If you know what to listen for with pinging then run whatever you want as long as you don't ping,  sounds like a metallic chatter noise.  If you ever hear it,  bump up to the next octane level

[MarAgt]

Well, the manual is perfectly unclear.  It just says #93.  Not RQ-93 or 93 octane.

From the service manual:

"Fuel type and Octane No. RQ-93 or higher unleaded gasoline"

RQ-93 is not 93 octane in the states. It's 87 octane here.


http://cfmoto-forum.com/general-discussion/why-so-little-hp/msg18790/#msg18790

Further, I asked this specific question of the service dept at the dealer weeks ago and was told that 87 octane was indeed correct, and that ethanol content is not an issue.

[NMKawierider]

Gota love translated documents ...I hear Canada is writing their own. Probably something the US should do as well.

[Sockman]

Gota love translated documents ...I hear Canada is writing their own. Probably something the US should do as well.

Great.  Hopefully they edit out all the "eh's".