Motorcycle Repair: 83 gs550es low rpm troubles, pilot jet, carb settings

Question
We can get the bike to idle properly but after trying to engage the clutch in 1st there is no power. It won't grab until about 3k or 3.5k. before then it bogs bad and sounds like it is sucking air or getting no gas but then comes to life once in the higher range. It'll run through all 6 gears great as long as the rpm's dont drop below 3.5k.  The bike came with 3 other sets of carbs and various parts. It had been messed with extensively. It has k&n filters and a 4 into one exhaust. It ran much better than it did after changing out the 4 pilot jets for the stock ones. It has one pilot jet screw on one of the carbs that is pretty stripped and wont budge up or down beyond 2 turns. Could that be the sole cause of this low rpm trouble? Do you know what the stock setting is for these screws (are they air or fuel adjusters). Also sometimes after coming to a stop the tach will sit at 3k until I engage the clutch then it will drop to proper idle but no power still.. Also, when we removed the carbs the needles in the slides were lacking these little platic circular spaces that sat atop of the extra set of needles the came with the bike. Once those were on it no longer had a sticking problem (the rpms) when revved up in nuetral. What is the highest the rpms should go when fully choked? I could ramble about all the various things but it would probably be better if i knew what you needed to know to more accurately diagnose these issues. Thanks a lot, Eric

Answer
You need to get everything back to stock as a starting point. The use of the K&N and the 4-1 exhaust will complicate this as the carb settings are very sensitive to intake restriction and back pressure. I would start by putting together a set of the carbs which look the cleanest and least damaged, identify all the stock parts and try to get a set of stock carbs on the bike. You may want to look into rebuild kits which will come with the correct jets. I can't tell you the correct position of the needle so you may need to find someone with this bike as get this information (the forums on www.thegsresources.com are down, but when they come back you can post there).

It sounds like you are lean on the idle jet. This could be due to too much air (the K&N?) or not enough back pressure. It also sounds like you are not able to properly fine tune the idle mixture due to blocked or stripped mixture control (its a combined air/fuel screw).

Once you get your rack of carbs setup, you can work on adjusting mixture and sync to get the idle and midrange fixed.