Sounds a bit lke this guys problem. Follow the link.
http://zongshenforum.com/forum/index.php?topic=186.0

PS Seeing your bike is actually a cruiser style , it may be worth re-entering this problem under the "Cruiser" heading in the forum. 

After looking through quite a few other threads, it seems to be a common issue that the CDI box needs to be replaced. Is it possible that the CDI box was damaged when the jumper cables were hooked up backwards? Does anyone know of a way to test the CDI box? Thanks

I think it would be more accurate to say that the CDI is easily damaged by connecting the power leads up the wrong way round. As it stands, the starter is working and the battery must still be OK and theres no spark. Unfortunately, CDI's are polarity sensitive so it was almost definitely damaged by the jumper leads being connected the wrong way round.
I think you've proved that so I'd be looking for a new CDI module.

PS And by the way....don't forget to hold in the clutch lever and lift the side stand before trying to start on this bike. That also prevents spark.

My guess is that the techy thinks you are going up too much with the jet sizes and has suggested u try raising the float level (did u write float bowl in error?) to get the mix a bit richer. If you fouled the plug up though you're already too big on the main jet (-if the floats level is now right-). Do you think you've got the floats right now? If so, you need to start the rejetting over again coz your floats were set too low prior to starting the rejet.
At this point it might be worth checking for small air leaks around the carby eg inlet and outlet clamps. Minor leaks may be causing extra air to be introduced into the system and leaning the mixture out. Can be checked by spraying a good layer of wd40 around the joints while the engine is running and listen out for any change in revs which would indicate a leak has been temporarily plugged by the wd40.   
Otherwise, keep going with the techs suggestions.

Just reading that comment re 4000rpm mark being the minimum revs to start charging sounds exactly the same as mine when the rectifier connector was unplugged. After i removed the seat one day i had somehow left the connector plug undone or partly unplugged. I then went for a quick drive and noticed my red charge light was on all the time at idle and didn't really go out until the engine revs were up -about 4000rpm. I knew this was way too high so i rechecked under the seat. Thats when i found the connector was unplugged.
In any case, even if u ride with headlight on, the charging light should go off at closer to 2000. Apart from when i had the fault, i've never seen the charge light come on above 2000rpm. Otherwise it sounds a lot like a fault in the charge cct.

There's a website i found that may be useful if you decide to test for faults in the charge cct. It's at this link: http://www.electrosport.com/

Too high a fuel level in the float chamber will cause rich mixture/flooding.

I just had a look at that 6sigma racing mod kit. Sounds like the way to go. They've got kits for just about every bike on the street there- but most importantly, one for the zong! If they live up to their claims they provide a complete carb kit with everything you need and after sales advice, phone help etc and full instructions with a money back guarantee. For $60 it may be better to order their kit rather than looking around for individual parts from a whole lot of different sources. I notice they ask you to provide details of the mods youve done so they can tailor the kit to your bike exactly. Definitely better than trial and error doing one thing at a time. Could save a lot of time.

As for running rich, this might work: Run the engine with some load , like uphill within the 1/2 to WOT range and watch for any hesitation or stumbling or bogging. When you find poor running, pull off the road and pull the spark plug out and check the plug for fouling on the center electrode. That insulator may be white if its running lean at that point. But if its rich it will be sooty or carbon fouled. Thats how i'd try to test for rich running. THe plug should tell you. By the way, dont forget to pull the plug before starting the test run. Make sure its nice and clean and gapped to 0.6-0.7mm or whatever your manual says.

Those other mods you mention like cutting the diaphragm spring and drilling holes in the slide etc,,--Ive not heard of those mod. Put it this way, sigma seem to know whats required for our carb and bikes taking into account the mods you've made, whereas the info about drilling holes in the slide etc is probably not a solution specifically for our Teikei CV carb. So i say go with the kit.

      

My bike is completely stock, so anything i say here is only guessing .

What makes u think the float bowl is emptying too quick? I can't see how the increased airflow you've created could alter the air/fuel ratio that much that you could drain the bowl. The needle and seat setup in the float bowl will easily compensate for the extra fuel you might be using after altering the needle clip height. If the fuel is too low then you may have a partly blocked fuel line or clogged screen in the fuel tank. Maybe check that.

If the carb is getting the fuel ok then what i think may be happening is as the engine comes rapidly off high revs, the mix goes briefly too lean, stalling the engine because the low speed carb circuit (pilot jet inside the float bowl) is too small for the increased air flow at low revs.  

I think you need to read the plug color, as you mentioned you were doing, to find out what the high speed circuit is doing (rich or lean or ok). Then the same for the low speed circuit. Drive at high revs for 5 mins, hit the kill switch and pull in the clutch. Pull over and check the plug. From your earlier post it sounds like the fuel is lean, popping and stuttering, You'd expect that after your K&N filter and new pipe. Then drive around for 5 mins at low speed, say less than 3000rpm and stop engine and check plug color.

Another quik test is :When the engine stalls after being warmed up fully does it restart better by pulling the choke on a bit? If so it sounds like it is lean at low speeds so the rejet of the pilot may be the way to go. Also, can you start the engine from dead cold without the choke? That could indicate the low speed circuit is too rich.

If you need to get new jets they should only cost a few dollars each, but where you  get them from I don't know.  May be best to check with a carb or bike shop there. Our bikes use TK (Teikei) carbs (type=MV30P-1J on mine) that are similar to the carb used on the Yamaha TW200 bikes - but they use a TK MV28 carb. So Yamaha dealers may be a source for parts. There is a US (Ohio?) website, http://www.endlessjourneycycles.net/  has a few posts about rejetting and general carby stuff. It may be worth ringing this guy for advice based on experience. Otherwise you may just spend a lot of cash and time and end up with a badly running bike.

Re the jet size, should be stamped on the jets, hopefully. May need a magnifying glass. I think someone put a post on this site about the jets but i can't find it.

I think that type of wear is typical of all discs. Mine is the same. Car is also the same wear pattern. So I wouldn't try to fix anything. Just watch for disc runout or fluid leaks. Mines done about 6000 mile and the disc is barely showing any wear. Pads are about quarter worn. No complaints about brakes.