Unscrew the cartridge - they're user replaceable so that should be easy. Bring the printout of the TSA website with the regulations and store it with the cartridge. Maybe improvise an extra cap to make sure it can't get pierced. Hope for the best.
Worst case they'll confiscate the cartridge but not the vest. Replacing these cartridges is cheap. I don't know what kind of vest you have and what size cartridge it uses, but if it's not too big you can try marine stores for replacements. Marine life vests seem to use cartridges up to 60 grams depending on the life vest size.
www.tsa.gov
Dunno if your motorcycle vest classifies as a life vest.
Some useful tips here: Traveling with your Life Jacket? TSA Guidelines - US Sailing
Worst case they'll confiscate the cartridge but not the vest. Replacing these cartridges is cheap. I don't know what kind of vest you have and what size cartridge it uses, but if it's not too big you can try marine stores for replacements. Marine life vests seem to use cartridges up to 60 grams depending on the life vest size.
CO2 Cartridge for Life Vest | Transportation Security Administration
You may bring a life vest with up to two CO2 cartridges inside, plus two spare cartridges in your carry-on or checked bag. Even if an item is generally permitted, it may be subject to additional screening or not allowed through the checkpoint if it triggers an alarm during the screening process...
Dunno if your motorcycle vest classifies as a life vest.
Some useful tips here: Traveling with your Life Jacket? TSA Guidelines - US Sailing