Basic Question re Main Jet Upgrade

[Wekadog]

I've just about made up my mind to do the needle jet / main jet / air filter mods described in this forum to boost my freeway performance. I'm committed enough to do my research and maybe buy a few supplies.

When I went Googling for a Suzuki Mikuni 140 main jet, I quickly realized there were a wide range of jets answering that description, Short ones, Long ones, Round ones, Hex ones, even plastic ones.



It's obviously important to get the right one. What's a more complete description of the jet I need to buy, so I don't end up with the wrong thing?

Cheers!