I have a Drz 125 2008 model. - 4 stroke

My mates have 2 strokes and faster bikes than me so i have to give it a flogging to keep up with them.

When i really rev it a lot and give it full throttle for to long the bike seems to cut out!

Its seems like its not getting enough fuel so the power is really low,
Iv been told the jetting is to small and to buy a ttr one and replace it but i want to know for sure before i do anything.

i have a bad history of dirty fuel but iv cleaned out the carbi and tank and it still
did the same.

what could be the problem and how can i fix it?

Try making it richer with mixture screw.

it is a 4 stroke and what is mixture screw, what will it do?

if you want more overall power, get yourself over to www.procycle.us and purchace a 150cc big bore kit, you can also buy a 26mm carb kit pre-jetted for big bore kits. also you get extra jets for tuning. all in all your looking at about £400. good luck and happy riding