Yup rebuild the carb. A worn float valve is likely causing this. Especially when you ride it’s probably jiggling open and flooding the carb causing a rich condition. Your carb is ready for a rebuild those seals will be very brittle
I just rebuilt the carb on my ‘93 and it was a great experience—read the carb sticky. Be very careful removing the fuel tank!! You will forget to about that rear fender attachment EVERY TIME. Put a big old piece of blue painters tape on that fender tip.
If you don’t want to do it here’s some info. I also just had the carb on my work ‘98 trx300 rebuilt by the Honda shop. Replaced the starter valve, primer assembly too. They charged my $275. I zeroed the throttle, set the pilot jet to 2 full turns out, installed it and BAM. Fired right up ran great—set the idle andddd DONE