So... I changed the sprocket and yes, the acceleration is a bit worse than before but i must say, that I'm satisfied with the results the bike isn't yelling all the time and I think that even gear changing is smoother!
In the next few days I will get a new chain and a new rear sprocket and I will change those two as well...
But I have this question... I changed the front sprocket slowly, step by step, I photographed the situation before I did every step further and I fitted the new one the same way as I removed the old one(only backwards of course ).. and now the bike is making this strange but not too loud repetative sound..like some part of the bike is rubbing on another..the faster I drive, the higher the frequency of the sound is.. I checked the rear wheel and I think that it is quite aligned.. so my question is, is it possible that i made a mistake? or is this something else, because i really can't identify from where the sound is coming.
When i fitted the new sprocket and the bike was lifted from the floor i started the bike and revved it a bit there (to see if everything runs smoothly) and I heard no sounds there..
Any opinion would be welcome oh and also THANKS FOR ALL THE HELP THIS FAR