Hi , I’m new to here, join a very long time ago and have not really been able to get time to look at site properly. My 1999 bird seems to have developed a hiccup which is quite difficult to explain but hope you can help. She runs amazingly for a bike that’s nearly 20 years old with 25k on the clock but has recently developed a stutter - runs fine drops a beat then runs fine again etc. Coz I don’t use her through the winter I thought it could just be dirty fuel so I changed the fuel filter. She been serviced not long ago at 24k but now looking for help , had been suggested it could be a coil ,plugs of fuel pump on it way out?