[kim]

Bottom end power can somewhat be correct with an enlarged valve cover. Available from LTR.

If it stalls to easyly is your idle set too low ?

Also hows the jetting ?, if your at the bottom end is not right you will loose power.
The LTR jetting kit has been succesful with a number people here on this forum.
Might be worth a try, from memory its about USD35.
Do a search for jetting here and you will be amused for hours..... Lots of very good info tho.

Off course, as you say, your gearing might be too high. Hard to say without knowing your riding style and speed.

Btw I use an Rekluse auto clutch and absolute love it and would recommenced it to anyone who want to listen. Occasionally they come up for sale (preloved ) on this forum.