Never experienced bucking downhill. I have a 4 speed and a Eddy carb.
So tomorrow I am going to do four tests.
1. Downhill with PCV, 2nd gear, 3200
2. Flat with PCV, 2nd gear, 3700
3. Downhill without PCV, 2nd gear, 3200
4. Flat without PCV, 2nd gear, 3700
I will report back my findings.