DISCLAIMER: I have spent hours and hours reading the forums and trying this and that but I'm at a loss
So a little introductory backstory
Hi I'm Danny I'm new here,
Okay so I have an 08 with 830 miles on it...
It's my first bike and i goofed up the oil change and put car oil in it. Well now its slipping,
BUT I can get it to engage if the bolts on the crank case are loose and the cable disconnected from the cam. How do I go about this so I camt tighten the bolts up and get back on the road if possible I have a steady hand and a dremel somebody stop me.

If you did only what you say you did...
drain the oil, take off the clutch cable and loosen the bolts...
why did you check to see if the clutch was engaged?

If the clutch engages with the case loose and slips with it tight, the throwout rod is too long, baring any other F'up.
With case off, the throwout rod should stick out of the spider about 12.5mm
any longer and you got what you got.
You may have some wear on the bottom of the basket causing the rod to be too long.  maybe, we've only heard wear on the bottom 1 other time.

Thanks for the responses everyone
Pardon my vagueness and lack of detail in the OP the migraine I'm nursing is making me dumber I hope this provides more insight and answers everyone's inquiries.

yes it's an 08 with only 830 miles on it.

I'm aware that means its twelve years old and its had to have sat for a while so when I got it I had to put fresh gas in it clean the fuel system clean the carb file down the white spacer. Change the air filter change the oil/oil filter this is the correct oil this time check cables and brakes. Eliminated backfire etc. I'm pretty good with a wrench.

Now forgive me please because I realize that this probably going to be the source of all my problems and I failed to mention it first off
I may have gotten away from myself trying to fix a symptom  instead of the cause.

I dropped her goin about ten mph over some rubble it stalled It was on its left hand side less than 5 seconds  ( the bike was lighter than my pride was) I walked her maybe another 30 feet to our hotel parked her and evaluated the damage a lil scuffing and a cracked turn signal, its starts, I have friction great!

Now here's the madness i left her idling while I went inside for what I thought was only going to be a pit stop well i got caught up with the warden (the bike got more attention than her) she ran out of gas after about an hour idling....

*wincing as I type this lot*
The oil filter cap popped out as well and I lost about a quart of oil I called my dad for help he brought the car oil and some gas we topped off the oil replaced, the cap, and plugged her back up.
Went to start her but the neutral switch wire came unsoldered inside the crank case (i fixed that headache last night) so I raised side stand and she fired right up purred like a kitten with no noise or other black flags.

Up until last night I had no neutral lamp no igniton unless side-stand was up, that day I took her home and removed the tank to clean up any oil that was smothering the connectors. I checked for continuity and resistance everywhere and found nothing a miss except the wire I couldn't get to inside the crank case and filed it under handle later.

Well later came about a hundred miles when her clutch started slippin at high rpms getting lower and lower and  until she doesn't wanna budge I've run about 6 quarts of fresh oil JASO approved oilthrough her since then and I've changed the filter once.
It's worth noting that the actuating arm on the crank case was clearly in favor of the bottom index as I had the lock nuts driven all the way in for the most slack possible and their was still about a half centimeter of tension at the actuating arm. Luckily the bike is still young I got everything off without tearing the gaskets repaired the wire inside then went to roll my bike in gear to see if it would still roll or disengage with nothing near the pushrod and low and behold the gears catch and she plants her ass.

Now is it possible that the pushrod was jarred and slipped out of the recess on the cam but is still in contact with cam and I'm not lining it up right when I go to put her back together or is it something
more malevolent?

Its seems like the depth of the recess on the cam is exactly the distance that is overcome at the last bit of tightening the case.
Could a thicker gasket be needed?
Am I missing something simple here?

I dont have calipers so I can only rough measure the rod unless I'm measuring only the flat shoulder to shoulder part of the rod and not including the rounded tips also the rod is discolored. It is normal colored where it sticks out of the basket then wear it enters at the port there is a small glazed line the circumference the rod and it's about five or so shades of grey darker the rest of the way into the basket.

I had to read your second post a few times before I think I understood the time line of what happened to your bike, so if the summary below is incorrect forgive me.

You changed the oil and filter and used automobile oil. presumably something with friction modifiers that was not specd for wet clutches.

But the clutch didn't start to slip until after you let the bike idle on the sidestand for an hour and the engine got hot enough to blow the filler cap out of the crankcase and eject a quart of oil - approximately half the capacity. You topped off the oil with the same car oil, and rode the bike and it was then that the clutch began to slip, eventually to the point where it would not engage enough to drive the transmission.

I have no idea what getting a clutch that hot with oil containing friction modifiers in it will do to the friction material on the discs but I suspect that that might be your problem.

I think you are going to have to get yourself a service manual. if you don't already have one, pull your clutch apart and take a look at the friction discs and the plates.

One other thing. Does your bike still have the OEM vacuum operated. petc*ck. If so, did the oil that blew out when it was running on the sidestand smell like it had gasoline in it.  A malfunctioning OEM petc*ck will allow fuel into the crankcase and dilute the oil. That won't do the clutch, or the rest of the engine any good either.

I would try the simplest solution first; change the oil and filter. Motorcycle clutches are known to slip when oil with moly is used. If this doesn't resolve the issue, you can then remove the clutch friction plates and steel plates and measure them in accordance with the FSM.

Danny

On my bike :

I put a piece of tape (outside) to mark where the pushing device on the in-side cover was pushing at a 90 degree angle to the rod it pushes.
Then cut the push rod to center its pushing stroke on the 90 degree area.

No need for a thicker gasket :  I use ultra Gray Form-a-Gasket w/no gasket at all.   It works Great.

But , the ROD has to be the right length.  No other way about it.

Did I understand you had 6 quart of oil in your bike ?

There is an error in the shop manual about the "Cupped Ring" while assembling the clutch.   Just do the opposite.   Better than just doing the opposite ... try to figure out why it is cupped ???