It would appear that there is a much discussed debate across the internet and across scooter nuts on which the little bugger requires in fuel, being that the scooters are of Chinese Origin and the USA vs. Others Octane rating is different.
My scoot says on the front below the seat, to use 90 or higher octane rating fuel. It also shows to be made by Jonway.
It would appear to me that, as I am a USA based rider, it is designed for only one kind of fuel. PREMIUM.
Whether you are in the UK or the USA or India, there are typically[as far as I know] 3-4 selections on most commercial pumps, and vary from store to store. Here in North Carolina, we have 87, 89, and 93.
Well upon a little research the lower the rating in the USA, the more Ethanol is used. Now I've heard it reported that a study of 1k gas stations were selling low grade fuel out of PREMIUM only selections.
Disregarding the false sales by the seller, the scooter is, as we know, of low compression. So, we know that there's not a whole lot of struggle for the engine to do a complete cycle, and it needs to be that way due to the size of the engine, especially the 50cc's.
Well, as far as I know, the higher the grade of fuel, the bigger the explosion. The lower the grade, the less UMPH per spark. Let's not get too technical here, because I'm trying to approach this simply.
Basically, with the lower compression, and not much of any power, and we know that a 2 or 4 stroke engine has only one piston, it needs as much BANG per RPM. I conjecture that if you use low grade fuel, you not only run the risk of getting poor fuel quality, but you will also have a harder time accelerating.
We know that through various parts replacing for performance, many of the stock obstacles can be overcome. But I don't have a lot of money to just start putting into buying new parts for my scoot.
if you have a better combustion, you will have a quicker rev, Imagine the engine could rev unlimited[as some CDI boxes allow] but without the engine getting too hot, lacking cool oil, or simply blowing up and warping. With this scenario we could jack the scooter up on it's jack-stand and start it up, then rev it wide open. Given let's say it wouldn't vibrate and move, you could allow and listen to it rev up. Well even if that were possible once it hits a certain RPM range, it will have a harder time continually going up in RPM's. Not that it's not capable, but that for the fuel/air mix, and the time it takes to go up, down, up, combust, up, down, up, combust, etc.
So, with a higher grade of fuel, you will get a slightly different BOOM in the block. Thus, resulting in a slightly faster push/pull on the engine to allow the new fuel/air in, and the exhaust out. So, we're not talking going from 40mph top-out to 55mph top out because you changed your fuel grade, but we are talking about better acceleration, and better gas mileage, as you won't need as much fuel to air mix to have the same BOOM.
I'm not sure what the real difference in grade is from USA to Europe, but I can tell you that 90 or higher octane, is high grade fuel, it is NOT low grade. If you want the longer life of your scoot, buy premium. If you are just a cheap skate that doesn't care if you're safe on the road, or can go up a hill in time to see the sun set, do what you will.
BUT, if you do care about your ride, as I do mine, buy the best.
Anyways, just my two cents.
EDIT: Also, my stock Carb doesn't have a low speed fuel/air mix screw, to make it lean/rich by turning the screw. Not sure if it's just wrong or what, but I do know that all my symptoms lately have been pointing to running lean. I put 87 grade in it before I found out it needs PREMIUM, so I've been having issues with acceleration and a constant, steady speed until my revs are high.
I know it's not much, but maybe it will help everyone out.
P.S. These things don't come with a 12 gallon tank, so buying PREMIUM is really reasonable. If you are just pinching your pennies so hard you can't afford it, having a little less of the right fuel, is better than more of the wrong fuel.
Why would you buy McDonalds double cheeseburger, 10 of them, if you could have 2 filet Mignon. I don't need a bunch of cheap-o sarcasm on why you have been using low grade and it's fine, etc. If you use cheap, go ahead. Ruin the darn thing. Just don't expect NOT to have to replace fuel parts after a year or less of running it daily.