A few things that worry me
 

Hey guys, I just recently finished putting the SHawk back together in streetfighter form. I had to replace my engine , so I bought a 1700 mile engine from a guy. Now the things that are bugging me may just be paranoia(think I spelled that right), but it seems to feel like it lurches a bit at speed, and the engine braking feels way more than I remembered. Now I am not running a fairing and I did go up 2 teeth on the rear sprocket. Also I have been off the bike for about a year and a half, not by choice. Its not so much that it feels like when it lurches that it will pull the bike from under me, its just enough to notice, maybe its just the wind resistence. Maybe the same with the engine braking but I don't know forsure. I was thinking maybe clutches since the motor has set for almost 2 years, what do ya'll think.

Two teeth in the rear is a pretty big gearing change. That could be part of it.
With only 1700 miles the clutch should be fine.
Was it stored with clean oil in it? I'd change the oil again (I'm sure you changed it once) to flush the stinky old oil out of it, then ride the piss out of it!

I changed the oil and filter before I ran it, with a k &n oil filter and royal purple oil. I drove it to austin and back before I had to replace the engine with the +2 rear sprocket, noticeable change, but like i said it has been awhile. I quess the 46 rear I have may as well stay in the box. I may go back to stock gearing then.

Slightly out of sync carbs are a likely cause. Got a mercury gauge?

Lean jetting will do it too. Also, do you still have the rubber snorkel on the airbox? Removing that has known to cause surging.

I recently had my '98 engine fixed after the CCTs fouled. I have the APE CCT's. Since i got my bike back from the shop, it has the same surging you are talking abt. I tried to sync the carbs, but it hasnt worked. Were you able to fix it?

Josh

Don't put away that sprocket, i've been running a 15-45 tooth for a year and a half and i love it. Around town the bike is happy instead of alway's wanting to switch gears. Oh ya and nasty wheelies to.

Royal Purple isn't energy conserving?

has been known to cause surging or prevent?

Cause. The airbox is tuned, anything you do deviating from stock inside of it affects the carbs' operating