Yeh it sounds weird, but do you think maybe you're expecting too much from the bike? At 80mph youre running it at its max designed speed. Over a couple of hours with that many revs and air cooling youre really thrashing the engine. It simply isnt designed for that sort of speed. Maybe the valves are burnt. I'd be looking for a bike with bigger engine with water cooling and maybe 6 speed box. I don't think the zong is quite up to that sort of punishment!!   I can see why you might be having problems now.

Sounds like a seized piston. I'd get it checked straight away as you will come unstuck with this one. You'll probably need a complete rear caliper and from the smell of it sounds like you've cooked the brake fluid. I wouldn't be riding it like that.

It's a good mod if u really need it but i'm still not convinced that this is anecessary mod. I would first be checking that the oil level is correct in the sump .If you really find that much oil in the airbox then you'd be continually topping your oil up in the sump  as the oil level would be below the Low mark on the sightglass window.  When the bike is leaning on the side stand you can't see any  oil in the sightglass window. If you can then you've overfilled it. You have to pull the bike up dead vertical to get a proper level reading.

I was reading a few other forums that mention  other problems that can result from too much oil in the sump  such as frothing of the oil and  premature gasket failures. 

So it may be worth checking your oil level first before doing any mods to the breather.

soccer_playa1579 did you sort this problem yet? Let's know what the issue was or if you need more help on it - just in case someone else has same prob.

It's not something simple like the stand has to be up to start the bike?  Your problem sounds consistent with that possibility. ie When you crank with starter, the stand is down and prevents ignition but when you push start, the stand is up and lets it fire up. The stand on this bike has to be in raised position in order to start the bike!! 

It sounds like you crank the engine but the engine won't start. Do you use the choke? Mine won't start without it. I pull it half way out then it starts first go. Then push it back in after a minute or two. This only applies to the first cold start. Once warmed up it doesn't need choke to restart. Even in summer it just cranks away without starting without the choke.

If your battery is not in good condition or getting a bit old (maybe a few years) you will quickly flatten the battery during cranking.  i don't think it's the cdi or else you wouldn't be able to push start it.  The engine simply can't run without the cdi as it provides the spark. If your battery is getting flat over night though, or not holding charge, you will be able to push start it as you apparently can, but it won't start the next day with the electric starter button (or perhaps even if you stop the engine and try to restart it.).
 
Does the generator charge light stay on after you push start it? If so the generator may not be charging the battery and therefore you will have a flat battery. In any case if the generator light comes on while you are riding then it suggests a fault in the charging system. eg battery/ generator/ wiring to either. Also, if you are cranking but don't see spark it could be that the cdi isn't getting the right volts/current . Put a multimeter across the battery terms with IGNITION OFF, you should see 12.5 to about 13 volts. If it's any less than 12v the battery is probably not charging properly or not holding charge. My guess is that the cdi needs about 12v minimum to generate sufficient spark to start the engine.  And don't charge your batt with a car charger as you will likely fry the bike battery. If you already did use a car batt charger, you may have damaged the bike batt.

Ok no probs Robbie, If it's the manual/book with a black and white cover showing a chequered flag that comes with the bike and is called "maintenance manual" then I have already seen that one. I also have a small book that is to be found under the bike seat.  Unless you have something additional, then I think  I  already have these. Cheers.

By the way, the other issue here is that the Zong is quite easy to work on yourself. Not too many special tools or complicated mechanical setups. If you work on the bike yourself this may well be a deciding factor. Some of the other bike names look like you need to be at least an average mechanic to work on them or else send them into a workshop for maintenance.