your main jet only effects 3/4 to full throttle, not the rpm jumps at start-up/idle, unless you were holding wide open trying to rev it, (i hope not on a fresh motor ?)
the lack of revving prolly has more to do with the float heigth, pilot circut/airscrew, needle clip setting, an airleak, or a tors problem if still connected ?
look in the carb section at the stickies at the top for the threads on each of those subjects
I am waiting on leak down tester so that will be known once that gets here... Even if i wanted to rev it wide open it wouldnt go there anyway...
On a separate note.. the clutch will dont disengage... The shop I have been buying parts from says that if the adjustments are right, you just need to launch it into gear and it should break free...
I did the adjustments twice, once when I first put it together and a second time when I bought new clutch plates and I followed exactly what it says in Clymer's manual... And I watched a youtube video that was posted on here jlsparky7 is the user name on youtube... When i had it apart i moved the clutch spring with pliers and you could see the clutch open and close... I have read on here that people soak there plates for 24 hours? I only soaked them for a few minutes.. The manual i have only says 'lubricate each clutch plate w/ transmission fluid).