Right around 4000rpm I get clutch slip only in first gear. Clutch is all stock. What's the fix?

Bike makes 101/112 just in case someone wants to know.

 

Not enough power to be the cause...just my un-professional opinion. My bikes pulling mid 120s for torque on the stock clutch with a heavy duty Barnett spring and its not slipping..yet lol...im trying. I don't know what year or model you bike is but if it's cable you might be able to readjust it and be good to go. That's where I'd start, adjust then if that doesn't get you any where it's probably time to take a look at the friction discs and the steel plates. Hope my rambling helps

 

Start with adjustment, if that doesn’t work then slap a fresh heavy duty spring in it. I just put one in mine. Holding power is nice and lever pull is negligible. Got the SE spring from Surdyke for less than $30.

clutch slip in first gear is odd though since you say you don’t have it any other gear. Normally even a wounded clutch will hold in first until you increase the gear ratio and load on the engine as you go up through the gears. Mine slipped from time to time in 4th and 5th, never in first.

 

I adjusted both the cable & removed cover to adjust the bolt w/lock nut. All good. I'm guessing I could have glazed the clutches? Idk?? Can that be corrected with sandpaper? Or other way?

 

I put an Energy One clutch in my 2012 CVO was easy and relatively inexpensive. Sure beats the heavy spring.

https://smile.amazon.com/s?k=energy+...b_sb_ss_i_5_13

 

If they're not too far gone you can deglaze with some sandpaper, just get them nice and clean after. Make sure you check the steel plates too...for bluing and for flatness...the slightest bit will give you fits. You can but the steel plates individually if the budgets tight.