1986 XT600 Only Start With Starting Fluid, Backfires

[86XT600SEA]

Hi guys, I just bought a 1986 XT600. Was only $100 (no title) and it started with a little starting fluid, but backfired like crazy. I checked and double check the valves (verified TDC with wooden dowel) and valves are in spec. I cleaned and replaced gaskets and float needle on carbs (need to set float level). I put new intake boots on as one had a gaping hole.

It will only start with starting fluid (bad I know) and will only run under throttle. It backfires like crazy (angry neighbors) and just sounds horrible.

The Previous owner had tried to repair the exhaust with muffler tape (probably exhaust leak) and the airfilter is shot so I need to order a new one.

I just ordered a new CDI for good measure. Hoping my buddy has an extra exhaust to test. Also just ordered a new battery.

For the air filter. I have the airfilter box, do I need to spend $80 on a uni filter on ebay or can I just buy the filter that wraps around it? https://www.ebay.com/p/Uni-NU-2285ST...55092767&rt=nc


Wondering if anyone has any thoughts. I did notice the ground wire coming from the timing chain area was loose. I just connected it to the engine using a cover bolt. Is that ok?

I'm new to dirt bikes but really want to get this thing running. Any help is much appreciated. Gad to be joining this community. Thanks, Ian in Seattle