It took quite a bit of searching to come up with a near perfect replacement spring. The dealer said the whole assembly and cable needed to be ordered ( I think not!)
Found a spring at a local spring supplier/manufacturer ( dealer was no help at all in recommending a spring place). Had to snip the spring off to get the right length and boy what a difference once installed. No more black smoke out the rear. I guess this is because without the spring and plunger in, the bike was running very lean ( too much air).- is this the right conclusion?