1973 Ossa Explorer - issues with engine transplant

[konrad]

15 hours ago, Triad said:

...bike hard to start, then starts, works for a short period (1-5 minutes) and then starts bogging.

The hard starting may or may not be related to the bogging.

When I'm trying to find thermal problems with electrical components, I use a heat gun https://en.wikipedia.org/wiki/Heat_gun and/or freeze spray https://en.wikipedia.org/wiki/Freeze_spray  

Freeze spray is fairly expensive.  A lower-cost alternative is a compressed air duster (like for computer keyboards) turned upside down.

BTW, I must complement your English, it's very good!