My 83 R80RT was worked on at a shop a couple years ago. As an experiment the mechanic lowered the metering needles to lean out the midrange. I think it is now too lean. I have to run with the choke for at least 2 miles on a warm day before it will run right. It feels like it is running out of gas at partial throttle. How difficult is it to raise the needles on the slide? My Clymer manual is not very clear and talks about loosening the manifolds and removing the fuel lines and choke and throttle cables before removing the top of the carb. These are Bing Constant velocity carbs. If I remove the screws holding the diaphram covers will the thing explode like a Jack-in-the-Box?