Changing the rear sprocket.
 

Due to the change of the cylinder to a larger one, the gears have become very short for this reason I decided to change the gear to JT R473-40t I am very pleased, because now I have a measured speed of 91 km at 6000 Rpm in 5th gear, that is about ten kilometers faster the gear ratio change is 10% according to the gear calculator https://sprocketcalculator.com/ I am going to buy another 37T gear and check, I hope that the bike will burn a little less now, because it has long gears and I noticed that the ride is completely different and calmer.I forgot to add that I need to shorten the chain.