When I try and shift into first gear at a stop all I get is grinding - won't shift into first the vast majority of the time. Sometimes if i kick it hard it will go into first. If I want to take off I need to shift into second. It does not grind if I am shifting into any other gear. I can also downshift to first if I am moving. Only when I am at a stop does it grind. Also, I just put on a new clutch cable. I adjusted the nuts back and forth to see if this would help but it did not. Any ideas???

Did this start with the installation of the new clutch cable? If so then I'd guess you need to properly adjust for the new cable. The goal is to have about an 1/8" of free play at the lever. You can get this by first adjusting the play at the end nearest the engine then fine tuning it with adjuster at the lever.

Fairly close. I adjusted the two nuts on the adjustment thread and moved it from one side to the other - close to both extremes - and it did not seem to make a difference. I originally set it up for about 1/8" play. I will take it back to that level and make sure I am still getting the grinding noise.

When did the grinding symptom begin?

Most likely is a dragging/not fully releasing clutch.
Cable adjustment, linkage wear/bent.
Warped clutch plates or friction material flaking off can have the same effect because the clutch doesn't fully release.

Grooves worn in the clutch basket fingers or drum spline are other possibles.

Knowing when this began might help to offer suggestions.

It started about a week ago - I put on a new clutch cable about a month ago and did not notice anything wrong at the beginning. Don't think the two are tied together - meaning that it did not start with the new clutch cable. I adjusted the cable at the motor to give myself about 1/8" free play at the lever. I confused myself on which way to loosen/tighten the adjuster nuts so I went to each extreme and then settled somewhat in the middle to get the 1/8" free play at lever.

I have encountered a few cables which began to stretch after a bit of use. Just a thought. I don't use a KLR clutch cable because I consider the original size cable to be undersized. I adapt a Yamaha ATV cable #5X6-26341-00; Motion Pro #306-5029.

It can be difficult to gauge whether the cable is stretching/giving but awareness of the possibility is step one.

More likely is warped clutch plates or grooves in basket/hub, IME.
HIH

If from a stop it grinds going to 1st but shifts ok going to 2nd, you may have a bent shifter fork in the transmission.

Thanks for that point, twinjet. I face palmed because I didn't think to ask whether the transmission grinds when stopped and attempting to engage second gear. I just assumed that the OP had checked this...

Sometimes I dispair at how muddled is my thinking. Wish there was a "hat's off smiley" to offer you.

I had a Yamaha 175 dirt bike with the same problem. Unfortunately getting to the shifter fork for inspection / replacement is not easy.