My 990 has been standing for a month or so in Vanwyksdorp. Went through to collect the bike (last ride was to Ladismith and back without any issues). On my way to Stilbaai I noticed that it backfired quite a lot when I geared down. Sometimes the idling is just too low and it cuts out and sometimes it revs over 2000 RPM......Could it be valve clearances or is there something else I can check?