Bogging on take off only
 

200cc Shineray (163FML). Recently deleted the cat, set the valves (exhaust was very loose), foam air cleaner (Double layer oil/dry). Much better midrange/top end. Take off is rough. Sputters and then picks up. Unsure of jet sizes (PZ27 Amazon special) Middle needle setting. Prior to adjusting the valves and cat delete, the plug was black. Too rich was my thought. No sputter prior to take off, but it was a $#@& to start. Much better now.

Suggestions for the sputtering/bogging?

1st, check your plug. If it's still black, clean it up or replace it. If it still sputters, 2nd thing to check is fuel mixture screw. It should be set between 1 1/2 -2 1/2 turns out. Adjust it half a turn at a time and check for sputtering. If you end up with it 3 or more turns out, you need a larger pilot jet. 3rd, check to see if pilot jet has some gunk in it; note sizes of jets, you may need next size up or down. 4th, check float height.

Sounds like too large of main jet to me put the stock one back in....
leave the needle jet alone ! leave it in the middle.... adjust the fuel/air screw
for fastest idle after you lower the idle to about 500~800 RPM.
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getting rid of the catalytic converter will just make it easier for the engine to breathe...
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typical symptoms for a flat spot just off idle is improper fuel air screw adjustment or someone has changed the jets !
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black plug means too much fuel or bad rings.... changing the main jet size will not make it go faster unless it can burn more fuel...
changing the main jet to a larger one and doing nothing else will usually result in a poorer running engine
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Bob....

It's not the main jet. ignore the previous post. Magician16 is on the right path. Low throttle bogging tends to be on the pilot jet side of things. Or a rich to lean/lean to rich transition between the pilot and needle.