02 cr134 big bore jetting problem

Is it rich or lean now?

Bogs and pings come from being to lean. Are you using race gas? Most big bores are set up for race gas. I would put in a bigger main for sure to get rid of the pinging.

How does it feel power wise with the bigger main?
With The low end bog and pinging you might be lean across the whole range.
Again what kind of gas are you using?
Did you by this bike from someone? Or did you modify it? If you bought it modded it might be worth your time to talk to the former owner and see what he used for gas\ oil, and what he used for jetting.

You will just have to spend some time expermenting with your jetting. I spent a lot of time jetting on my 144. To start try lowering the clip on your needle. Just make one change at a time. I wish I could be more helpful. Have you asked Eric what he would recomend?

My sons -01 cr has a Eric Gorr 133 cylinder ported for low/mid and is set up for pump gas....I know the jet sizes for 01 and 02 are not the same , but here is what we have done:
Main jet: 400 (standard 380) Its still a little rich , will probably end up with a 380 or a 390.
Needle : stock , lowered 1 clip.
Slow jet : 37.5 , standard is a 45 , will probably be replaced by a 35 , its still a little rich.
The bike is ridden at sea level , and is completely stock otherwise. The weather is really tricky here at the moment , lots of rain ,and the temperature changes very much from day to day, and the tracks are heavy to ride , stressing the engine. A bit too lean , and the engine will seize.Our jetting is therefore a bit on the rich side , just to be safe...
Our jetting with the standard cylinder was 360/380 main , needle lower by 1 clip , slow jet 40. With the 133 it runs really well , pulling 1 tooth less on the rear without problems.