I've been struggling with my SU's for a couple weeks now. I just can't seem to get the mixture right - the motor feels weak under load unless I set the carbs so rich that I can smell strong fuel-ey fumes.
Even though I'm 99% sure that I've got the dreaded throttle shaft leak, I thought I'd replace the PCV valve and eliminate a potential vacuum leak in the crankcase ventilation system.
I was able to pick up a replacement PCV valve at my local auto supply (Fram FV237) and 18" of 5/16" vacuum hose for about $4 total. While I was at it, flushed plenty of gunk out of the flame trap with some carb cleaner.
Well, I've still got carb troubles, but for under $5, I've got a PCV circuit that'll hopefully last me another 500,000 miles.