Home Forums 2-Cycle Racing Old KT-100 – Use VP MS98L or 93 pump gas?

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    • #33252
      Robert DeGroff

      I have an older KT-100. I’ve had some confusion on what gas is best for this engine. Some say 93 octane pump gas from a gas station actually runs better in this engine. True? Which is best for  carb tuning? engine life?

      Next question is Motul 2T kart oil? What ratio?

      Not looking to be competitive, just weekend warrior fun. Thanks!

      KT-100 / 2001 Margay Brava 2k frame

    • #33273
      Finch Guenther

      Some may disagree but I would say the Vp would be a better choice. It’ll be much more consistent then pump gas and the lead is good for the bearings. As far as oil I would use a castor based oil for an air cooled engine mix at 8oz per gallon.

      Finch Guenther

      #51 CRG KPV

    • #33325
      brian downing

      Castor is “old school”

      In this day and age castor has no benefit over high quality, 100% synthetic oil.

      Especially for a weekend warrior. Synthetic has little to no carbon buildup, less carbon cleaning. Castor is a vegetable oil, and left sitting on a shelf too long will go rancid, just like any other vegetable oil, while synthetic is fine sitting for years.

      Motul 800 2T is great stuff.

      For weekend warrior stuff, track days and practice, I see many people using pump fuel.
      Why waste the money, but make sure you don’t have any detonation or it’ll cost you later.

      The VP is inexpensive insurance; no ethanol, and the lead does lubricate, so if you can afford it and have easy access to it, why not spend a  little extra?



    • #33416
      Walt Gifford

      If you have a Can exhaust 93 pump gas is ok. If you have a pipe you better keep it pretty rich on 93 octane. A pipe likes Sunoco purple or VP C-12, VP MS98L is ok too. The problem with race gas is it goes south pretty quick so, you have to get it in 5 gal cans and decant to one gal cans to keep the air gap down. If you’re getting it from a large track tank, good luck.

      Blendzall 460P Green Label Castor is still the best oil you can use in any kart engine but it’s more work to use it. Red Line Two Stroke Racing Oil is one of the top synthetics and it’s what I recommend.


      FAA certified jet engine and aircraft technician,
      Nicholson Speedway class champion 2001,
      Yamaha KT100 Service Center,
      41 years karting experience

    • #33436
      Robert DeGroff

      Thank you ALL for the advice! Much appreciated!

    • #33528
      Steve O’Hara


      If you are running a KT100 with the IKF/WKA required minimum 11cc in the combustion chamber and you are not worried about passing a tech inspection at a race then the best choice of gas is the lowest octane pump gas at your local service station.

      Generally speaking, octane ratings are an indication of a fuel’s resistance to detonation and you’ll find that the higher octane blends need to be run very lean to perform well. If you ignore the conventional wisdom and try running the low octane gas you’ll discover that the engine will run clean and produce excellent power with a richer mixture that results in lower engine temps and longer component life. You’ll also discover that the engine is not as sensitive to the mixture settings and will run good under different weather conditions and with different drivers without as much attention to the needle settings.

      It’s important to understand that the compression ratio mandated by the IKF/WKA rules is extremely low so there is virtually no chance of detonation unless the engine is run much too lean. Accordingly, there is no need for the expensive race gas with high octane ratings to protect the engine from detonation.

      The KT100 is not a thoroughbred racing engine, it is an industrial engine adapted to karting with the emphasis on cheap, reliable and simple to run. It does need or benefit from expensive gas blends.

      As for the oil… any of the oils mentioned above will work fine but I still prefer the castor based oils. I recommend Burris castor at 16 to 1. It is a very clean running castor and produces very little “carbon” buildup in the engines.

      Steve O’Hara

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