I think a lean mix usually causes blueing on the pipes, but maybe it could be yellow too.??
Are you experiencing excessive popping or backfiring when decelerating?
That can indicate a lean condition. Check the "Verses" for marbling or coastering in the exhaust section.

Here is a spark plug color picture to help "read" your plugs.
http://www.google.ca/imgres?imgurl=...=183&hovw=275&tx=155&ty=105&page=5&ndsp=14&ved=1t:429,r:1,s:53&biw=1090&bih=419

You want a light tan or gray color on the ceramic insulation.
Too light or white indicates a lean condition.
Black or soot indicates rich/flooding or burning oil.

The air/fuel mixture is factory speced at 1 5/8 turns out for US bikes.
Try 2 1/2 turns and test ride. Increase 1/4 turn at a time if needed. 3 1/2 turns max. Screw falls out at 5 turns. Seal with dab of silicone when adjustment is done.

 

I thought the bluing came from too rich causing it to ignite inside the pipe but I could easily be wrong.

I don't have any backfiring issues at all so no indications there.
I'll check the plugs and screw in the morning but not sure how much the plugs will show; they're only 5 months old or so. When I replaced the others, they were tan though.

Thanks.

 

The yellowing will start to turn blue. If the pipes are yellowing near the top it means engine is running lean and hot. If it is yellowing about a foot down on the pipe it usually means it is running rich. As OldHos said check the color of the plugs. 2 1/2 to 3 turns out usually works well.