Help, I can't disassemble the chain to get the speedometer from a Honda C90

Hello everyone, my first theme, I am from Colombia and I have bought a Honda C90, it is the 3 motorcycle of this brand and displacement that I have, they are very good. I had to change the speedometer viewer but for this I had to disarm the complete chain and I have not been able to, the tachometer is still subject to the viewfinder for some screws but I cannot access them, I need a step step by step to disassemble the entire manubriu including Barola, the manual in this forum does not bring any information, only motor images, thanks for the help.