I have just rebuilt a honda gx200 generator new rings gaskets etc it will run wwithout the exhaust attached but as soon as i place the exhaust in position it stalls the engine even without screwing it

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Check gaskets / seals / piston rings as it sounds like oil contamination is fouling the plugs.

wait a while till you run it in
turbo boost should be low on a rebuilt motor at first

new rebuilt engines smoke till the carbon ring forms on the new head gasket

if not happy after a week check out the turbo

look at crank case breather pipe from rocker cover if that's all clear the engine has worn rings or cylinder or both

are your plugs fouling with oil? then you may have a valve or ring problem, if you are burning the plugs up your fuel is too lean. also, make sure your timing and all with distributer are good

Intake, combustion, exhaust system is supposed to be separate from lubrication system. You have a breakdown somewhere in that separation evidenced by gas smell in oil and oil coming through exhaust. Possibly head gasket or piston ring. Take it back to the folks who rebuilt it and ask them about it.

Double check the tolerances, a loose lock nut on a tappet can make noise. Some times a bad or missing exhaust o-ring can cause a ticking sound, make sure you remove the old exhaust gasket and install a new one.

Did you just have the motor rebuilt by a reputable shop? If so take it back and explain the problem and they should take care of it.
If not you are kinda on your own. What kinda tick? Could be leaking head gasket, base gasket, bad valve guides, incorrect bore, piston, rings. Incorrect ring gap, leaking exhaust gasket, out of time, etc, etc, etc, etc.

You know what they always say about the color of smoke... blue is oil, white is water and black is  i don't know lol.   Anyhow, if it was just recently rebuilt and you're getting blue smoke then oil is making it into your pistons OR you are burning off oil somewhere when it gets hot.  If you are seeing the smoke from the exhaust only, then think about piston rings, head gaskets, all the typical stuff that gets replaced on a rebuild.  It's near impossible to say exactly where to look so that's the best I can tell you.  I would lean more toward the piston rings.
Good Luck

Sounds like poor engine rebuilt work. The rings probably were not aligned properly. they need to be placed in their proper positions. The valves, guides, weak spings, etc. (Was your cylinder or head machined) Also you could have used incorrect rings-size. Keep looking online for manual guides