I have been driving a new Fiddle III 4Tacter with Euro 4 for over 400 km now. It ran to Tacho 45, which according to Navi were real 44km/h. During the first 300 maintenance I had a 2mm steel throttle ring used instead of the original 3.6mm (comic dimension) plastic throttle ring. Now I have Tacho 50 and am completely satisfied with the speed, especially since I flow significantly better in the city traffic… For a little more passage 8mm weights were added instead of the original 5.9mm ?… The seller and also a mechanic explained to me… Now the previous full throttle was 45km/h without any problems or jerking. The now 50km/h are like that, which if someone holds me from behind and at the same moment let go again! This is the way in 1-2 seconds clock. Now I have to let go with the 50 with the gas, which I then again on 49, 48 … back fall, and then give again 1-2mm more gas, then either have a harmonious ride for a short time, until it starts again…with the jerking. Before I took back a bit at 45 the gas tap, about 2/3 to 3/4. but also had no jerking and thus a comfortable full gas attitude. Are you aware of the reasons and you can turn off the jerk at full gas mechanically or differently or I have to wow myself at it. My seller probably knows no solution except that I do not d he is the first in the Euro 4 models. Is there a sensor in there, which now grabs when a certain speed is exceeded.