Motorcycle Repair: ninja issues, air leaks, air intakes

Question
Hi, I have an '86 zx1000. I had to replace the engine with a similar age zx900 engine but was forced to use the 1000 carbs. It has a stage 3 jet kit on it, there are minor air leaks around throttle shafts and intake boots (carb spray mildly affects engine speed). After going through carbs several times, and doing everything in my skill level, I still have 2 problems. Here goes... To start engine you need to manually choke (hands over air intakes), or direct fuel. It will not even sputter with the choke engaged or throttle at any position. The choke linkage works correctly and the passages into the diaphragm areas are clear. Once manually started the engine works nearly perfect and still needs to warm up with the choke on (seems like choke works when the engine is running, just not for starting). The motor has run for years with this exact configuration and gave no warning for this starting issue (one week it started perfectly, and quickly on it's own, the next week it wouldn't and hasn't since. My other issue... If you rev the engine and then suddenly release the throttle,(around 8000 rpm's) it quickly goes down to around 4000 rpm's and then VERY slowly goes to idle. When I force it to idle (with the clutch, in gear) it stays at the idle fine. I don't have the money for new carbs and am not positive it's them anyway. I hope I made since of this to you and would very much appreciate any help to get my baby and I back on the street again. If I left anything out, please ask me @ amsecor@msn.com. Thank you very much in advance... Andrew... P.S I sync'd the carbs and they look perfect.

Answer
Hi Andrew,

Check cylinder compression and valve clearances. Both must be within service limits for the carburetors to work properly. If compression is out of spec, perform a leak-down test.

Remove spark plugs and describe their appearance to me. You may compare plugs to those on NGK's "Problem Plugs" link:
www.ngk.com/sparkplug411.asp

Seal (repair) all intake air leaks. The erratic idle may be caused by the air leaks and/or improper carb synchronization. The added inertia of the clutch and transmission will cause idle to return to normal more quickly. Do you remember what the Mercury or vacuum needle readings were when you checked synchronization?

Review the information files I sent to your email addy.

Get a service/repair manual (check Ebay).

Look into the above and advise. Let me know about the history of repairs and winter storage for this MC.

Respectfully,
Mark Shively