Warner
Member
I sell a lot of the China import scooters/mopeds with a 49.5cc engine. The owners manuals claim that 90 octane gasoline is the minimum requirement. They all have the Honda GY6 clone engines with no timing adjustment. I started experimenting with fuel types/octane ratings and found the following to be true.
All of the brands we sell say not to use ethanol enhanced fuels. 87 octane fuel runs terrible; 92-93 octane fuel makes them run worse than that! 89 octane fuel with "no ethanol" seems to be the happy medium. 90 octane leaded fuel works the very best. It's available at most farm cooperatives here in the midwest. It's red in color; and actually smells like gasoline.
A product called "Marvel's Mystery Oil" can be used as an additive to any gasoline to provide excellent upper cylinder lubrication.
Brett
One thing to remember about recommended octane levels coming from other countries is that they have different rating systems. Japan and Europe use a system called RON or Research Octane Number to determine the octane rating of their gasoline, while stateside we use a system called AKI or Anti-Knock Index to determine gasoline's octane rating... Interestingly, to further complicate things it would seem that our own AKI system is actually derived from the average of the RON system and another more complicated system referred to as MON or Motor Octane Number... So, to recap our methodologies for measuring gasoline's octane rating are different, but share some common elements...
So, with the commonality of RON in mind a good rule of thumb is as follows, multiply the foreign RON Octane rating by 0.95 and you will have the US AKI equivalent.
( RON Octane Rating x 0.95 = AKI Octane Rating )
90 RON Octane x 0.95 = 85.5 AKI Octane (US measure)
98 RON Octane x 0.95 = 93.1 AKI Octane (US measure)
100 RON Octane x 0.95 = 95 AKI Octane (US measure)
So, as you can see the 93 or 94 octane fuel we are all paying an arm and a leg for is actually quite comparable to the higher octane fuels found in Europe and Japan. I suspect that the recommended 90 Octane rating that you are getting from the Chinese motors is based off of the RON Octane rating and would equate to AKI (or US method) Octane rating of only 85.5
Warner
PS - What compression ratio do those Chinese engines run at?
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