1995 Yamaha Big Bear 350 won't start

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! 

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.

Hi Guys!

New member and could really use your advice. I would have to believe this has been an issue for others but a search here came up with nothing......? (Probably me not doing search correctly)
 
I have an 87 Big Bear 350 YFM350FWT
The OEM Mikuni BTM carb is shot and would rather replace than rebuild.
It is no longer made and I have had good luck with NICHE carbs so I ordered a #K-CRB-0006 This was what they said was replacement when ordered. This Carb only uses 1 Throttle cable. The Slide is linked so it uses one. (OEM had 2nd cable coming through top to move slide)
 
Problem is when I ordered a replacement Cable from NICHE (#C-CBL-0061) the Cable wire is a little short, not allowing Throttle to return all the way down to Idle position. I called NICHE and they are at a loss. Haven't gotten back to me after 2+ weeks.
 
What would you recommend other than a carb rebuild?
Can I just use 1 of the OEM cables (It is the right length) and snip/disconnect the other that went to top of Carb for Slide?
Or ??
 
Thanks in advance for any advice you have!!
 
Dave

Good morning to all !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Let's see if we can make this a daily event.

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