After reading the rest of your comments, sounds like the previous owner before you had some idle issues and made a decision to plug that idle jet to compensate for their problem to try and lean out the idle. The other carbs would take care of the fuel mixture during idle. But that isn't how things are fixed. You find the problem and fix it according to the shop manual and don't circumvent any part like that. If you don't own a specific manufacture, Horse Power, and year shop manual, I highly recommend buying one. It covers every little thing concerning only your engine and doesn't try to cover every engine made. So a lot better step by step explanations of everything. Also buy the proper size replacement jet(s) and also see what other jets in all the carbs could have been changed as well. At this point you really don't know what somebody else was doing with those carbs. Then after getting everything back to a known standard, then you can work towards any problems that show up. But you have to have a known setup and baseline to work from... JMHO!
