Sometimes it's the simple stuff.

I installed the stock carburetor.  Problem solved.  No more irritating little glitch at light load.  In the process of setting up the stock carb for the modified engine, I reviewed some articles on the Mikuni CV.  I found a pretty good rundown from an outfit called Factory Pro.  They use the float level to tune light load conditions.  I found that interesting.

Since it ran fine with the stock carburetor, I figured my problem must be the S&S carburetor.  Its not the exhaust header or the new hi-flo air filter.  That float level thing kept grinding at me.  I checked the level several times.  It was exactly on the S&S spec, but that spec is for a big V-twin.  I'm runnin it on a 40 inch single.  

I readjusted the float level to 1/16" above the S&S spec.  End of problem.  Now it responded well to tuning and in no time flat it was runnin better than ever.  

I am amazed at how well the thing responded to such a minor adjustment.  It makes perfect sense.  The idle & transition circuits were designed for a much larger engine that pulls a lot more manifold vacuum.  The little Savage mill with the big cam just didn't have the oomph to lift that fuel up into the low speed circuit when the throttle plate was in the final stage of transition.  Raise the fuel level and it doesn't have to lift as far.

If you are interested in a pretty good step-by-step for tuning the stock Mikuni CV, check out this Factory Pro link.  It's got some good stuff in there.  You learn something new every day.

http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_...

Or, the hi flow filter offered less resistance, so there was less vacuum in the carb body. Years ago I had a 550 Honda in my Mcy maintenance class with a K+N filter and no airbox lid. Ran like crap. Covered half the hole that used to be the airbox lid with my hand and magically the bike revved clean.

Glad it worked out!
So, on the 550, we did install larger jets. I was just trying to show the kiddies the effect of intake resistance on fuel pickup.
Looking forward to another dyno run for your bike!

The rocker arms also looked fine, and the rocker shafts were oiling good.

I reached out on the forum to see if anyone else had seen retainers like this.  No one had seen it.  I assumed that the stock retainers can’t handle the high-pressure springs and figured I would have to put it back together with the stock valve springs.  That would require a cam with less lift, so I decided to reassemble with the stock DR650 cam.

I needed another set of retainers, so I pulled down my original stock head with the intent of cannibalizing the retainers off that.  It only has several thousand miles on it.  Low and behold those retainers exhibited the same fretting/pitting/cracking (whatever it might be).

I ordered another set of retainers, but they were on super backorder.  And to be honest, I really didn’t want to run the stock retainers, they looked sketchy for this application.  Now what?

I tried a set of valves for a 1995 DR650.  The DR650 valves are identical to the stock LS650 valves except the cotter groove is situated lower on the stem.  The RD titanium retainers fit just right on the DR valves.  Now I could put it back together with the 340b cam.

This shows a spring seat after trimming next to a stock spring seat.

Everything looks in order.  The valve tips are no longer situated below the top edge of the cotters.