Best fuel option for X125T-WC

The manual specifies “Use leaded or unleaded Premium gasoline 95 octane”. Previous owner said they used VP C12 gas. Looks like C12 is a leaded 112 octane fuel, which seems like overkill. Also, I do have kids with me, and so if it works OK perhaps I’d prefer unleaded. Should I look for VP C10 instead, which is a 100 octane unleaded fuel?

I’m still calling around, but here are the options I’ve found somewhat near Seattle:

  • Ethanol-free 92 pump gas – is it acceptable to mix in a quality octane booster to get to 95?
  • Trick 100 octane, unleaded, 10% ethanol
  • Trick 110 or 114, leaded, 0% ethanol
  • Sunoco 100 unleaded, not sure about ethanol content

Otherwise, is there a particular VP or Sunoco formulation that’s recommended? I think there are some dealers nearby but are closed at the moment.

Where are you located? I know most of us run ks110. If you call IMUSA they will tell you only c12

Seattle area, so SIMA is an option though far away and probably still recovering from the flooding. I’m not in a rush, but prefer something that doesn’t take a tank of gas to pickup.

No problems with leaded gas around my kids? I guess even if I don’t run it, others will, so maybe it doesn’t matter? But any drawbacks of running C10 instead?

What is KS110?

If you can find it, VP C9 is your best best. It’s 95 MON, unleaded and ethanol free. It is a relatively new product that replaced VP MS93. A lot of series will be switching over to it for 2022.

You have my attention. Which series?

Rotax has already switched to it as of last year, at least for the East series, and I’m told another, bigger series is switching as well. I don’t want to say which one, as it’s not official yet. As we all know, SKUSA went with Aspen, as C9 isn’t high enough in octane for the shifters (Aspen is 98 vs 95 for C9). The trend will be toward phasing out leaded fuel, which as someone who handles leaded fuel 7 days a week, I am happy about.

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I was curious about the Aspen and C9 so I looked up the spec sheet and both are RON of 98 or so. The Aspen Sport actually says 98, the C9 spec is 98.5. This is purely for informative basis, as I didn’t know either. Europe does use much lower octane than the US racing wise so the shifters certainly can run on the “lower” octane than we’re used to running here.

This article claims VP C10 is used in karting: link. I couldn’t find anything about C9, other than VP’s page saying it’s an “economical” alternative to C10 – but they cost the same and are equally hard to find.

This article claims SKUSA is switching to Aspen Sport, which is 96 octane (R+M/2) unleaded ethanol-free: link. As far as I can tell, it isn’t sold anywhere retail.

To confirm, is running ethanol-free 92 pump gas a bad idea (with or without an octane booster)?

The biggest difference between dedicated race fuel and pump gas is consistency. On a four-stroke its not as big a deal, but on a 2 stroke you may be chasing carb settings more between batches. If VP C10 is available and allowed by your club, I would likely go that route. Always check your club rules. Many have a spec fuel that they check in tech.

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Quoted for emphasis… Race fuel is about consistency across batches first above anything else. Low octane racing fuels are a thing as well.


So, are the “race fuels” out of the pump considered consistent enough? e.g. the “Trick 100” or “Sunoco 100” I mentioned? They cost $8-10/gal so it’s not cheap, but more convenient to fill and relatively nearby. Or does it really need to come straight from a pail/drum?

KS110 comes in a barrel. Readily available from roger. And will be much more consistent than any pump. Especially in the colder months.

Like so many things in life the answer is, it depends. In theory race gas from a pump should be just as consistent as from a can or barrel. Unfortunately variance comes from the environment. Like Lindsay mentioned, temperature, humidity and barometric pressure all have an effect on the fuel being stored. Tanks at pump stations are not sealed like a barrel or can is, so if the supply is not being turned over in a timely manner then it is subject to greater variation.

If the station you are buying from is selling a good amount, it will likely be fine. If they only sell a little here and there, I would avoid it.

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