Higher octane fuel from the petrol station won't really affect you too much.
It could just be a bad set of gas from the station.
Should try refilling it back up again.
Higher Octane fuel, if you're wonder, contains anti-knock properties. This property stops the engine detonating.
The reason why companies say it makes more power, or better on fuel, doesn't reside on the fuel alone.
It resides in the ability to utilise the higher anti-knock properties.
For you, on a stock DTR, what would this mean? Nothing. It means absolutely nothing. It doesn't mean more power in any way shape or form.
If you were in a modern EFI car. It means that the ECU could advance the ignition slightly to utilise the higher knock qualities of the fuel.
But since our bikes are carb, and I presume you're fairly stock tune, then no, it means nothing.
Me on the other hand, I run higher compression, more agressive advance ignition, higher combustion temperatures. All of those encourage detonation. Thus, higher octane fuel is a must.
There really is a lot to fueling, this was just a quick dump of information. Read Graham Bell's Two Stroke Performance Tuning if you want more information.
