1988 suzuki quadrunner will not start

I did a compression test on my 2005 Bombardier Traxter 650 CVT and it's 75 PSI.  service manual only talks about leak down test.  No specification for engine compression the manual.  What does 75 PSI tell me?  Thank in advance.
 
A little history of this machine.  640 miles.  Picked it up about 2 years ago, not running. Probably the computer.  Tested all circuits and confirm it was the computer.  Long story short, I watched a Youtube video and fixed the computer. ATV now started and runs.  BUT, it tops out 20 MPH.  I cleaned the carb 3 times also using a Mikuni carb kit after the second time.  Slide in carb is going up and down.  Only adjustment for fuel is at 1.5 turns out.  NGK Sparkplug had soot on main part but brown on the electrode.  Champion sparkplug is brown.  I check CVT clutches and they both appear to engage like they suppose to.  Checked valve clearance it's 0.00, I can't get any feeler gauges in-between.  I check timing chain I believe it's in the correct position and hasn't skipped.  I removed muffler plug and drilled into muffler to try and make sure it wasn't plugged.

My uncle bought a Baja 250, 2006. Knew there was no spark since the get go. He don't know anything about quads so is getting me to help him try to get it running...
 
battery is bad so I connected battery charger to it to crank it over , cranks over well , but no spark .... 
Lights and everything work fine , but with each crank over using the e start switch , the display reads 999 888 777 666 ... Right down to 000 and repeats itself . 
 
He managed to get a parts bike , I changed over the CDI and the coil and the stator from the parts bike and there was another black box by the voltage regulator I changed over ... I used my multimeter to confirm as much as I could works , it's hard without knowing which wires are which , and I cannot find any diagrams online for this bike ? 
 
Do you think it could be the Killswitch? There's so many wires coming from there I don't know where to start . Also I should mention it appears the fan on the front of the bike has been taken off (the wires have been cut too ) 
 
If this bike sparked it would run . The previous owner said he parked it one day and it just wouldn't start after.

2022 Sector 550, 414 miles on it and the gas gauge reads empty.  I topped off the gas and it didn't change.
There is no fuse that I could find.  No access at the gauge cluster.
Wiring on the top of the tank looks good, properly connected.
Could the sending unit in the tank be stuck or broken?
Has anybody removed the tank lid?  Any tricks?  
Any other ideas?
Thanks for any help,
Clyde

What should I do about this , bad oil leak where the filter cover bolts on . Can I use some gasket maker 

I have a 1988 Quadrunner 250 2wd. My brother in law sold it to my son for $20...had been sitting outside for several years. Got it home and had it running in about 30 mins. Ran it a bit and then went to looking at the carb as it was having trouble idling. Was getting it pretty close, then started losing spark...Also, it wouldn't start up every time...only about 1 in 5 tries. Anyway...now, it has what I can only describe as "intermittent" spark. I can get 1 light spark right when the start button is pressed and sometimes one when it's released...but none while cranking. 🤷‍♂️

I have replaced the spark plug, ignition coil/wire, and traced wires best I can. I noticed a couple frayed wires at the pickup coil where it enters the case. So, now I have the cover off, stator and pickup coil out and trying to test the coil. I do have about 114 ohms resistance for pickup best I can tell. And I can read minute voltage when I drag a magnet across it. Could it still be bad? Can a bad ignition switch/button cause this? (I did have the switch off to oil the choke cable)...pulling rope makes no difference though...any ideas or help would be greatly appreciated!!! It's the intermittent part that's throwing me off!