Does the leaded gas cause a carbon buildup greater than what you would normally get?
Yes and No. On a well built/maintained two stroke motor that is properly jetted with a good quality premix at a ratio of 40:1 or 50:1..... you might tell that the leaded has a little more carbon build-up. BUT, on 90% of the 2S bikes out there there is so much left over products of combustion that you can't tell the difference in buildup. Cheap premix at 24:1 ratio, leaking crank seals letting oil into cylinder, over oiled air filter leakage, and not tearing down the cylinder to scrape out a seasons worth of carbon build-up causes more issues with buildup.
Are there downsides to switching back and forth, such as if I want to try it, or if I simply want to use it when I can?
You can easily switch back and forth when needed, just make sure you keep the premix ratio correct. But, once you try some race gas... even at 50/50, you will have a tough time going back to 91 unleaded. Your bike will just not be as snappy.
Do you recommend only using pump leaded, or would an additive be fine?
True lead additives do help raise and stabilize octane in unleaded fuels. BUT, in high performance motors like a KX 2S, the unleaded pump gas just is not engineered with the high energy chracteristics in the fuel from the start. SO, you may take the 91 unleaded to 95 octane with an overdose of additive,
but the fuels designed energy level will still be less powerful than VP C12 mixed 50/50 with 91 unleaded. Most true lead additives can be multi dosed to increase octane but usually only by 2 pts per dose.
I had posted some questions before about jetting, because I was/am getting some surging. Do you think that running higher octane and leaded gas will help smooth that out?
Yes and No.... What bike and year do yo have? Whens the last time it has been rebuilt? Top end and Bottom end with new gaskets, crank bearings and seals? Is it jetted right on? Any air leaks at the reed block or intake boot? Surges at idle or when you let of the gas rapidly after full or 3/4 throttle? So many variables to take into account. Funny, but these motors are very simple and yet can be very difiicult to fine tune. Eveything affects everything when it comes to motor performance.
Sly
