Gasoline octane requirements

[Yager200i]

It seems the Kymco manual states, "Use unleaded gasoline with a research octane number of 91 or higher."
 
The Research Octane Number (RON) is not what we use in the US, we use the Anti-Knock Index (AKI). There is also the Motor Octane Number (MON), further confusing the issue.
 
http://en.wikipedia.org/wiki/Octane_rating
 
In order to translate between RON (which the Kymco manual uses) and AKI (which US gas stations use), we have to do some math.
 
MON is a more stringent octane test than RON, so the MON will generally be 8-10 points lower than the MON.
 
So, we let this website do the calculations:
http://www.wolframalpha.com/entities/calculators/anti-knock_index/ra/6k/ue/
 
We know Kymco wants a RON of 91 or higher, so we plug that into the RON input on that page. We'll assume MON is 10 points lower than RON for this first run, so MON is 81.

The result is an AKI of 86. So, Kymco says with a RON of 91 and a MON of 81, we can run 87 AKI octane gas just fine (in other words, the 87 octane number as it shows at US gas pumps).
 
Let's do another calculation with the MON set 8 points lower than the RON.
That gives an AKI of 87. So again, we should be just fine running 87 octane gas in the scooter, according to the Kymco manual.
 
So, it would appear that running 87 octane (AKI) gas should be just fine for these scooters.

[CapnJ]

I've been using Regular, 87 Octane since my 2nd tank with No problems. Seems to work well, no knocking no matter how hard I push it and I push it hard.

[ScooterWolf]

I was told to use Premium or higher. No problems so far.

-Wolfe

[Yager200i]

Things about gasoline and octane you might not know:
1) The octane level of a fuel defines how hard it is to ignite, and how fast it will burn. Keep in mind that as the fuel is burning in the cylinder and increasing pressure, the piston is moving down and effectively lowering pressure. The amount of work done on the piston during the combustion stroke is a product of these differences. So, it stands to reason that for high-RPM engines with high piston speeds, using the fastest burning (lowest octane) fuel that you can (without getting knock detonation) will increase the amount of usable power the engine produces. If the fuel burns so slowly that the resultant pressure rise is negated by the piston moving downward, then no effective work can be done on the piston (and there have been engines developed that have experienced this problem).

2) If you live at a higher elevation, you can safely use lower octane fuel than if you were at a lower elevation. This is because the further you get from sea level, the less air your engine takes in, which lowers your effective compression ratio. A lower compression ratio means that you can use a lower octane fuel without risk of detonation knock.

3) Gasoline with a lower octane actually has a higher energy density than gasoline with a higher octane. However, if you have a more sophisticated engine and use a higher-octane fuel, the engine control unit can advance the timing such that efficiency will be greater than when using a lower-octane fuel. Most ECU's run the engine at a point that is right before the advent of detonation knock, so by running a higher-octane fuel, the ECU can advance the timing more and increase efficiency. That said, if your compression ratio isn't sufficient to take full advantage of the higher octane fuel, you'll see no benefit from running a higher octane fuel.

(Does anyone know if our scooters utilize a knock sensor to adjust timing?)