Aghh youre embarrassing me now
so this may be harder to find than the last issue, I would stick with the carb, David you said you cleaned it and obviousy from the outcome not near well enough. The carb would be my first port of call again, a total strip including removal of the needle jet (emulsion tube) here is a dirty one from a DT175. If yours is this type take care when tapping it out of its seat. I use a pin punch of the correct size and re fitting it if I remember right it only goes in one way (locating peg?..cant remember for sure but watch out for one.
The chamber that fits into has a small hole into the bottom of the carb bore (engine side) seen on this picture
All jets and also the float valve need to be removed and I recommend at the very least inspecting them closely...I use a magnifying glass...
Buy an aerosol carb cleaner and spray it everywhere and compressed air supply is also useful if you have the means.
Only when your carb is cleaned 'as new' can you eliminate it from your power issue and move on from there.
Can you not redline the bike in 2nd 3rd 4th? or close to it?
Oh and about that compression test you did earlier using your neighbours finger...Not Really