Conversion of DT 125 to DT 175.
Year 1977
So I finally got the cylinder and head from ebay.
Can you please advise me what all needs to be changed during the rebuild?
I know there are other parts.
1. Piston pin bearing.
2. Chip 160
3. Another needle?
4. Freewheeling chip?

I have a cylinder from an AG 175 in the exhaust channel there is a small hole from the cylinder to this channel.
Is it because of reduced performance?
Furthermore, the head does not fit the cylinder, what type of head should I look for?

Thank you Daniel

You need a DT or CT175 head. Be careful not to get a head with 6 boltholes, they are for later motors.

Cylinder And head

Small hole in exhaust channel is just to make starting easier on the old Ag's.
Nothing to do with performance, well, reduce it if anything.

Images of a "77 parts are a bit difficult to pin down & goes from "76 to "78 wherever i look.
But if yours has the big base & not using the long studs then it'll need the 6 stud head.
If i'm understanding the story!!.