Motorcycle Repair: fuel pressure reg...1982 honda cbf, fuel pressure regulator, cb900f

Question
I've a 1982 cb900f that's had it's carbs gone through recently, ran perfectly for months, and now acts/feels as if it
is overfuelling badly. i was told there is some sort of fuel pressure regulator that's near/part of the petcock that's the likely culprit. my manuals seem to be missing the appropriate pages. Any thoughts ? jury rigging is allowed. i'm just trying to keep an old lady on the road.
Thanks for your response and expertise

Answer
Hi, The only fuel pressure change that will ever happen on your bike is due to the level of fuel in the gas tank.  There may be a vacuum shutoff on the carbs, although I have not seen that on the 900F; it could have been rigged in there by a previous owner.  If your bike is running super rich, then I usually suspect one of the floats set to the wrong height, or needles being in the wrong position; but if it ran OK for a while then the problem becomes more tricky.  Has the bike been run regularly?  If so perhaps there is a blockage in one of the needle valves.  If not then suspect some old fuel is perhaps jamming things up.  Are all cylinders running rich?  Get a thermometer at home depot that allows you to get a reading off surfaces, and verify the exhaust header temp to ensure all cylinders are running equally hot.  If you don't have a thermometer like that, and don't want to buy one, a quick test can be done with some water in a spray bottle and do the 'sizzle test' after the bike has been run for a while.  Each pipe should sizzle the same.  If one is much cooler, perhaps an igniter is failing or a plug or plug lead...  Let me know.