I have not caught anything on an underspin yet. I can't concentrate if I don't do it. Should I fish a 1/4 oz on a 7ft medium heavy lews with my 6:1 shimano or my 7 ft medium heavy lews with 7:1 lews reel?

Underspins are a slow retrieve bait, especially one as light as a 1/4oz. I'd go with the 6.1 reel, cast it out and reel as slow as you can stand. 

17 minutes ago, Bluebasser86 said:

Underspins are a slow retrieve bait, especially one as light as a 1/4oz. I'd go with the 6.1 reel, cast it out and reel as slow as you can stand. 

Yes, or slower.

20 minutes ago, Bluebasser86 said:

Underspins are a slow retrieve bait, especially one as light as a 1/4oz. I'd go with the 6.1 reel, cast it out and reel as slow as you can stand. 

Will the blade still work?

1 minute ago, TKFactory said:

Will the blade still work?

If it's a quality underspin it will. It should have a BB swivel that will spin at almost any speed as long as you have the right balance of weight/blade/and bait on it. 

I use a 5:1 reel for underspins and crank it slow.

I use a 7' medium fast spinning rod with a slow and steady retrieve and have caught some good smallies on the underspin.