Hard to explain, which Problems my bike makes, i will try as good as i can. After total restauration i think my bike should run better than it does now. I run out of ideas and to be honest, i don´t know what is normal or not on this old DT´s as i never rode one before. Bought my 75`as a wreck and spend 1.5 years, trying to bring it back to like-new condition. First start-up after new Piston and cylinder bore (+1mm, Woessner) was fine, but acceleration at about 4000rpm was spluttering. Turning throttle on full, running over 4500 was ok. Terrible vibrations i had also between 4000 and 4500 , below and above almost none. I lowered the carb needle and sputtering was less. Finally i am now in top ring of the needle, means leanest in medium throtte position. Spark plug looks good, brown color. The vibrations at 4000 were really painful, i changed the crankshaft to an overhauled with new bearings and connecting rod. Vibrations now are less, but still there at 4000 - 4500 revs. What really surprised me, the motor doesn´t run more than 6000 revs. Even not in lower gears. Max speed is 100Km/h, more, it doesn´t go with stock sprockets. Carb is restored but keeping old needle, piston, jets.. as they looked good and had the right numbers on it. Float level is adjusted fine, as well as the points, which are exactly 3.2mm ahead. Exhaust is burned-out and clean. Air filter is stock and oiled carefully with a bit of oil. That is now the situation for 800Km and i have no more ideas. Is it possible to eliminate the exhaust as a possible reason by running the bike only with expansion Exhaust, without spark arrestor ? Other ideas are really appreciated,

First thought on lack of top end is exhaust but i see you've done that. Just be very sure the spark arrestor deep down in the tail muffler is clean as carbon lumps from the main exhaust get caught in there & trapped. With Vibration my first & main thought is engine mount bolts not tight enough. Or the exhaust is bolted tight steel to steel without rubber isolating mounts. Left side crank bearing loose on the shaft can vibrate but never happens on those bigger motors. Would be obvious if you grabbed the flywheel for up & down. Swinging Arm excessive side play can let engine vibration be felt to a point, but only sitting still & revving it.
I must say the bike looks very nice.

Thanky you for your comments.
Exhaust is mounted in rubber. Motor mounts are tight and crank bearings are the 2nd new set, meanwhile.
Maybe it´s the flywheel itsself, which is not balanced right.
I will check the spark arrestor and maybe ride around the block without it .
Best regards, Guido