Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
If the thing ran perfectly for the last owner last week, then plug caps would be my first port of call, just tighten them on a turn and / or wd40 sprayed up inside the cap - for some reason I had a spate of plug caps fail across 3 differnt bikes in the last 4 years, none previously to that, wd40 seemed to revive them briefly - enough to get home / keep commuting a few weeks. It cannot hurt to do a full service for peace of mind in any case.
If the bike has not been used since 1994, it is still worth checking the oil is getting to the top end and the clutch plates are free before you blow the top end. No mechanic will check this on a service unless instructed.
certainly sounds like carbs, but also check timing ,is it getting fully advanced ??also,what colour are the plugs?