Two strokes don't and never did need lead in the fuel. In fact, the lead was a common cause of plug fouling.
Octane rating is different. And so is the addition of ethanol. Use gas without ethanol if you can find it.
One counter-intuitive piece of advice from Mercury Marine (and I've heard the same from Ford Engineers) is the use of "mid grade" gasoline is actually better than using the "high octane" stuff!
In the US the pump octane is the average of the research (RON) and motor (MON) octane ratings. The MON rating conditions used to rate the fuel are closer to "real life" conditions that cause knocking and pinging... So you want the highest "MON" rating you can get! The problem with high grade gasoline is that it's cheaper to mix in oxygenates, butane, ethane, etc which really give the RON a boost but can hurt and don't help the MON. But since the average of the two ratings is used, they do it anyway and end up with a higher advertised octane number on the pump but a fuel that performs worse in "real life" than a lower "average" octane fuel with a higher MON component.
P.S. Avgas uses yet another set of conditions to rate the octane... 100LL is roughly equivalent to "regular" auto gas when tested using the MON protocols.
One other thing to put in the back of your mind. The new fuels with ethanol will gum up jets and eat away rubber parts in your carb if it is left in too long, by that I mean it may be only good for a couple of weeks.
I made a mistake and forgot to drain my carb and fuel tank on my modern KTM that I last rode a couple of months ago. I had to pull the whole rear of the bike off last night to clean the carb. All the jets were plugged solid. I have been only putting enough fuel in my Enduro's for what I am going to ride them and drain after use. This time I forgot.
Extremely good point! Another thing on the older bikes with real aluminum carbs is that the ethanol can attack the aluminum and when you open it up it will be filled with corrosion... later models used zinc alloy (Zamak) and are not as susceptible.
On a nice old classic that might not get ridden too much it might be worth investing in some of the non-ethanol fuels that are available from VP and others for small engines with aluminum carbs and older rubber... cheaper than all out racing fuel and comes in 5 gallon cans either already premixed or as straight gas.
www.vp-sef.com/
or maybe this:
www.vpracingfuels.com/vintage
You might contact VP or another fuel supplier for expert recommendations.
Probably not practical or needed for a daily driver... but depending on how you use the bike it might be well worth the cost of better fuel rather than spending money later on repairs?
Contributors to this Article: MarkT & Scootern29
