Very lumpy running at low revs....

Hi all, noob question here probably. My recently acquired GRiSO has done very few miles over the last 5 or so years according to MOT records and is very lumpy at start up and when running below 3/3.5 K revs, but absolutely sings higher up the rev range.

I've put higher octane fuel in so see if that helps it at all, and it ran much better on this but then on starting it again today - very lumpy again.

Might this be dirt in the fuel tank, before I go investigating other things like throttle bodies etc.....?

Thanks for your patience

Ed
2009 GRiSO 1200 8V

Are the plug caps arcing to earth? When was it last tuned properly? Is it rollerised?

Hi Pete - it is rollerised, haven't checked the arcing but will do. Hasn't been tuned properly for a long time I reckon.......

Thanks

Well a full tune-up would be a good starting point. You'll need diagnostic software and a manometer and read up on what not to touch on the throttlebodies but it's a very simple procedure.

Thanks Pete - mucho appreciated