Bike had been sitting for about 5 weeks.  Charged battery and attempted to start.  Starter motor whines but does not turn over.  Removed starter motor and hooked to a battery and turns over just like it should.  Reinstalled starter and whining but not turning over.  Rocked the bike in 4th gear as  I read somewhere the sprag clutch stick as this sometimes fixes the problem.  Again, no change.  

Any thoughts on what to do next would be appreciated.

It quite likely is the sprag clutch. Remove the starter and with a long screwdriver try to turn the gear that meshes with the starter gear, it should turn one direction and not the other. That will prove if it is indeed the sprag clutch.
Have you had the starter apart prior to this as we have seen quite a few put together so they spin the wrong way, very easy to do.
Some of the guys here have use diesel oil (not fuel) in the engine to get the gunk out but you will need to push start it which is not easy but once started with the deisel oil it often comes good fairly quickly.

For what its worth when I had mine apart I found that it went back together really easy, then checked it and found it was the wrong way. To get it back together the correct way is little more tricky. It felt like it wanted to go back together the wrong way.

If in doubt put some marks on it before you open it. Then reassemble it the opposite way and pop it back in. If that solves it then you are sorted. But a common thing is to mark it before disassembling, then go to town cleaning the outside and when it comes to reassembly the marks are cleaned off. So when you know its right do use a permanent means of marking like some scrapes of a sharp screwdriver on the casing where the end and casing meet. Or a dab of paint.

'But a common thing is to mark it before disassembling, then go to town cleaning the outside and when it comes to reassembly the marks are cleaned off.' 
That's precisely what I did.  Fortunately my bud came to the rescue and I managed to put it right with his help.  When it comes to marking the case, a scribe mark is the way to go!

Thanks for the responses.  i have not hard the starter apart.  I checked the sprag clutch and it does turn one direction and not the other.  Any chance it is the starter relay?

If you can hear the starter spinning then it's highly unlikely the relay is cactus.
Try to push start it and then refill with some oil for deisel cars and run it for a few miles and see if there is a change, if that fails to get action then it may be that the sprag clutch needs manual cleening and the gearbox and the intermediate housing needs to come off for that.

brickrider wrote:'But a common thing is to mark it before disassembling, then go to town cleaning the outside and when it comes to reassembly the marks are cleaned off.' 
That's precisely what I did.  Fortunately my bud came to the rescue and I managed to put it right with his help.  When it comes to marking the case, a scribe mark is the way to go!

That's why its important to have a reliable supply of for these moments.....

Thanks.  Will push start and see what happens.

I had a similar problem on my RS 16v and 75RT. Disassembled the starter and cleaned it our.
Has been working perfectly since. Its a quick and easy job!

Was having sprag problems so I ran 15W 40 synthetic Shell Rotella diesel engine oil in my 16v K100 for about 3000 miles this summer.  Not one starter problem since putting it in.