Got my hands on my first enduro, 1973 CT175. Trying to use it as a true dual purpose bike, riding from my house to all sort of local trails and mountains. What i have quickly learned is its almost a death wish to be outside neighborhood streets on this thing if there is a hill or head wind. Climbed 1,000' on pavement over about 5 miles yesterday and the bike would not pull 5th gear at all, I was down to 4th at 7k rpm to try to maintain 45mph (55mph road, single lane each direction). No idea how others ride these bikes, but is 7k for a few miles on end acceptable? I am much more familiar with 4stroke dirtbikes, not road sections or 2 strokes.
Compression test shows 100-110 hot, WOT, starts and runs good, just doesnt seem to have the power for 5th unless its flat or downhill (hit 60mph coming back down). Would a milled head be worth it to try to overcome the 5th gear bog? would the extra heat not be worth it? last thing i want is to be sitting on the side of the road blown up. Bike currently is mostly stock, stock pipe but missing the spark arrestor (id like to find one) and a slip on foam air filter. Considering richening the needle 1 notch to see if power on hills feels any different. just picked up 2 new plugs yesterday to try to get a fresh plug read as the other one has a lot of carbon buildup from the getting it running phase. 

Burning out the crap in the exhaust pipe might help. Also KDI has the spark arrestor.

On my CT3 I had the cylinder milled down about 30 or 35 thousands so the piston was at zero deck height at TDC. This did give my CT3 a boost . Also, I do agree with goatboy56. Pull the spark arrestor and make sure it is not clogged up, that will definately limit the power