Should I use a fuel additive if i don't ride my bike much?

The simple answer is a big fat NO.
Seafoam, Stabil and all the other snake-oil additives are simply that... snake-oil. Here at Limey's we do easily over a thousand carbs (if you count a bank of four as four carbs) a year and the worst ones to clean after sitting are ones that have had a fuel additive in the gas.

These 'additives' create a hard, crusty film that is impervious to ANY kind of carb cleaning, including carb cleaner and ultrasound cleaning. Plus it's corrosive! We literally have to hand scrub everything in the carbs and it's a nightmare to get perfect, especially if it has got into any of the small passages in the carb body. This is probably due to ethanol being hydroscopic and the water mixing with these additives causes this horrific carb-clogging.

If you are not going to ride your bike on a regular basis (especially in hot climates, as this exasperates the problem), you have a few choices:

  1. Drain the carbs (this is the only option for those with vacuum petcocks, unless you have an 'off' position)
  2. Turn the gas off, if that's an option and run the bike till it dies
  3. Use ethanol-free gas, such as 100 low-lead or ethanol-free race gas
  4. Don't do any of these things and expect to have the carbs cleaned whenever you want to ride it, but at least ethanol is clean-able.

Sadly, some gas companies are using additives that do the same damage, as the owners of these machines swear they didn't use any bottle additive.
So, the moral of this story is either ride your bike often, or put pressure on the government to stop subsidizing Monsanto... erm, I mean farmers to grow corn.