I have the twin Hitachi SU set up on an A14 with GX head. I recently cleaned out the carbs, and have been trying to tune them. I balanced them using the tube in the ear method which seemed to work fine, but setting the mixture was a different story.

I've read two methods for setting the twin SU mixture. One I read off a link from the 1200 wiki, and one that I read from the Haynes Weber/SU carb manual. The wiki link says to push the lifter pin in all the way quickly and listen to the rpms, but Haynes says to push it in only 1/32" after slack has been taken up. A lean carb will cause the engine to die, a rich carb will cause the rpm to rise and the a correct mixture will cause the rpms to rise slightly, then fall slightly. I'm not sure if it really makes a difference if you follow the wiki link method or the haynes manual method; I tried both.

Anyways, when I got the rpm to rise slightly and fall slightly when either of the lifter pins were pushed in, the engine idled poorly. One thing I remember about tuning carbs is that as you adjust the mixture and you approach correct, the rpms should rise. So this confused me. Do I trust the lifter pins or the rpms?