They make the bike run.It helps with air fuel.Keep the gas from blowing back out in the intake.It pretty much like your valves in a stroke ,if you had broke it wouldnt run right at all.Flooding  slugish power .They let gas in on intake stroke and they shut on exhaust stroke.. Also if you had the stock reeds in the motor.I would replace them with a set of Boysen  replacement reeds.Their pretty cheap and they work alot better then stock.But you can get alot better cages for the money it just what you want to put into it.But if they never been change i would do that.24 year old  i say they are pretty worn out.