87 trail boss has spark and fuel but won't run

Check the link and ATV Forum

https://www.google.com/search?q=1985+Polaris+250+Trail+Boss+won%27t+start

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Question edited for clarity, plus full make model (what it is).
Question moved to our only Polaris Trail Boss category.

That is a lot of stuff to change all in one go. One of those items has caused the issue in what was presumably a running ATV? Always best to swap out one item as a time and check everything runs as expected before moving onto the next, checking after each replacement.

The last sentence is confusing even with my edit. I take it you mean it turns over, it catches the odd time, but won't run. In that scenario, and with all the parts you changed, I would check the spark plug gap and that it has a good fat, blue spark. The other thing is the carburetor settings as per the service manual. Engines only need fuel, compression and a spark at the right time.

Try and check your timing?

Here ya go..

Polaris 3087037 CAP SPARK PLUG Cheap Cycle Parts

lots of reasons check spark again and fuel to what filter carb? engine problems basically are gas and spark so tells me its gas pull plug squirt some gas 2 stroke make shure its oil/gas 4 stroke gas only in cylinder use a eyedropper or a clear gas line of fuel to put fuel in cylinder put plug back in fire up if starts problem in carb if no start may have jumped timing check air filter may even have a mouse nest in it most people don't drain gas out of carbs for winter drop carb clean bowl with pure white vinegar clean all jets pilot / main reasemble

DOWNLOAD POLARIS TRAIL BOSS REPAIR MANUAL

trailboss-manual.blogspot.com/
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Replace spark plug (gap correctly),Drain all fuel, replace fuel filter, replenish tank with fresh fuel, do a thorough readjustment of the carb settings (last resort - remove and rebuild carb)

try cleaning carb and running ethanol free fuel with injector/carb cleaner in it

Did u choke it ? -stroke are very cold blooded Mine(2003) needs a choke after sitting 1/2 hr at 70 degrees.