<div class="htmlview paragraph">A well balanced use of alternative fuels is an important objective for a sustainable development of individual transportation worldwide.</div> <div class="htmlview paragraph">Several countries have objectives to substitute a part of the energy of traffic by ethanol as the renewable energy source.</div> <div class="htmlview paragraph">Investigations of limited and unregulated emissions of two 2-S scooters with gasoline-ethanol blend fuels have been performed in the present work according to the measuring procedures, which were established in the previous research in the Swiss Scooter Network (since 2000).</div> <div class="htmlview paragraph">The investigated fuels contained ethanol (E), in the portion of 5, 10, 15 and 20% by volume.</div> <div class="htmlview paragraph">The investigated 2-S scooters represented a newer and an older 2-stroke technology with carburettor. The newer one was investigated with and without catalyst and the older one only in the original state without catalyst.</div> <div class="htmlview paragraph">Since there is a special concern about the particle emissions of the small engines, the particle mass and nanoparticle measurements were systematically performed.</div> <div class="htmlview paragraph">The nanoparticulate emissions were measured by means of SMPS (CPC) and NanoMet <span class="xref">*</span>).</div> <div class="htmlview paragraph">The most important results for application of ethanol blends on 2-S scooters are: <ul class="list disc"> <li class="list-item"> <div class="htmlview paragraph">addition of ethanol to the gasoline provokes a leaner tuning of the engine operation,</div></li> <li class="list-item"> <div class="htmlview paragraph">influence of the leaning effect by means of ethanol depends very much on the basic original tuning,</div></li> <li class="list-item"> <div class="htmlview paragraph">for the investigated newer 2-S scooter the irregularities of combustion and loss of power were remarkable, with higher ethanol content,</div></li> <li class="list-item"> <div class="htmlview paragraph">the richer basic tuning of the newer 2-S scooter enabled a satisfactory driveability with E10,</div></li> <li class="list-item"> <div class="htmlview paragraph">the older 2-S scooter with richer basic tuning was little influenced by ethanol blends: good performances and reduction of CO and of fuel consumption up to E20, no impact on (nano)particles emissions,</div></li> <li class="list-item"> <div class="htmlview paragraph">at the beginning of operation with ethanol blends some release of particles (residues) from the engine and exhaust system was observed (wash out effect),</div></li> <li class="list-item"> <div class="htmlview paragraph">with catalyst there is an efficient reduction of CO, HC, PM and NP, the higher share of ethanol can lower the exhaust temperature and due to that lower the catalytic converter efficiency.</div></li></ul></div> <div class="htmlview paragraph">The present investigations with ethanol did not concern the durability of parts exposed to the chemical influences of ethanol. Also the cold startability, particularly in extreme conditions was not addressed.</div>