If your Polaris side by side starts and runs but dies the moment you pull the choke off, stop chasing your tail. There's a good chance the answer is a clogged pilot jet — a small brass jet inside the carburetor that controls fuel delivery at idle and low throttle. Block it even partially and you'll have exactly this problem.
This machine ran fine for months after the last carb clean. Then a few weeks ago it started dying at idle for no obvious reason. Same symptoms every time — fires right up, runs on choke, dies without it. Classic fuel starvation at idle.
The Diagnosis
When a carbureted engine runs on choke but not without it, it's telling you something specific. The choke enriches the fuel mixture to compensate for a lean condition. The fact that it needs that enrichment just to idle means the idle circuit isn't delivering enough fuel on its own.
Pilot jet. The pilot jet is the small jet in the carburetor that feeds the idle circuit. It has a tiny passage — small enough that even a microscopic piece of varnish from old fuel can restrict it enough to cause exactly this symptom.
Fuel mixture screw. This machine has an aftermarket dial-style adjuster on the fuel mixture screw — somebody already pulled the factory tamper plug and made it accessible. Worth checking the setting as part of the process.
The Fix
Pull the carburetor, locate the pilot jet, and clean every passage with carb cleaner. You should be able to spray through one end and see it come out the other side unobstructed. If there's any hesitation in the flow, keep working it until it's clear.
Reinstall and set the mixture screw. Start at 2.5 turns out from lightly seated — that's the baseline for this era Mikuni carb. Warm the engine up, then fine tune from there. Turn out for more fuel if it still stumbles, turn in if it blusters and runs rich. Find the highest stable idle.
The Result
Idles clean. The decel pop that showed up after the fix is minor and typical of a carbureted machine this age running slightly lean from the factory. Nothing to worry about mechanically — it runs strong under load and idles without a fight.
What To Check If This Doesn't Fix It
If you've cleaned the pilot jet and set the mixture screw and it still won't idle, the next places to look are an air leak at the carb boot or intake gasket, a cracked or missing O-ring on the mixture screw itself, or an exhaust leak pulling air in on decel. Spray carb cleaner around the intake boot while it's running — if the RPM changes, you found your leak.
Most idle problems on machines this age come down to fuel delivery or an air leak. One of those two things is almost always the answer.
Never say it can't be done.