I have read that one way to test for a too large of main jet is to accelerate under full throttle.....and once you reach a steady pull you can start to roll off the throttle.  If you feel the bike begin to pull harder just as you start to close the throttle - then the main jet is too big.

The reason that this happens is that when the throttle starts to close the mixture begins to lean out with a closing throttle.

Also a rich mixture makes the bike a bit sluggish.  When I am not sure I start going bigger on the main jet until it is obvious and you can hear the bike begin to bog down under full throttle....then I start dropping sizes until I can feel the bike hunt/surge at full throttle (which is too lean).  I then know the correct jet is between those two extremes.

I doubt that a rich main jet would result in a problem when you close the throttle.  The only sources of fuel with a closed throttle is the pilot circuit.  I would expect the pilot jet and the idle mixture screw to be the place to look.  You might also try raising the idle speed a tad.  (Is this issue better or worse when the bike is cold)?

You can eliminate all the scratchin your head by actually collecting some measurable data.  Put a camera on your speedo and record some acceleration pulls.  Then use a stopwatch to time the pulls.  Change your main jet and do some more pulls.  If it slows down, you are goin the wrong direction with the main jet.

This old post should be helpful.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1577664388/0#5

When I was adjusting my VM carb, I mounted an oxygen sensor and it showed me a lot of what I thought about carbs - was wrong.

I was surprised to learn that when you close the throttle - the intake vacuum does increase - but the mixture goes lean!  This happens because the slide drops and the tapered jet needle begins to close off the needle jet.  When the throttle is completely closed the needle is way down in the jet and has almost completely stopped any fuel from flowing.....even though the high intake vacuum is pulling a lot of air past the nearly closed slide.

The popping/banging/after fire when you are decelerating with a closed throttle (or close the throttle when shifting) creates a lean mixture, and it can become so lean the spark plug cannot ignite the mixture.  The fuel/air therefore goes through the engine and into the exhaust unburned - then either it gets hot enough to ignite in the exhaust or the engine does fire a time or two and the flame into the header ignites the unburned mixture in the exhaust.  You can easily reduce the amount of this noise by opening the throttle a tiny bit to allow more fuel/air to enter the cylinder....or not completely closing the throttle while shifting.  Once you get into this habit it becomes second nature when you are on your Savage.

The fuel/air mixture also goes lean when you are opening the throttle.  When the slide goes up - the intake vacuum goes down and less fuel is pulled out of the jets.  This is a very temporary condition and goes away very quickly once you stop moving the throttle.  This is why some carbs have accelerator pumps - it corrects this temporary lean situation when the throttle is opened.  If you "crack" the throttle open quickly - you really exaggerate the lean condition.  I can remember when I was in high school if I rode my friends Honda Sl100 - a quick throttle would result in a large "cough" as the engine stopped running....you had to open the throttle a bit slower than "instantly".

I looked to see where I saw that comment about rolling off the throttle and better running for an instant indicated a too large main jet - it may have been for a CV carb....not sure.