I have an 2004 Polaris ATP 500. The machine idles fine, but when you apply the throttle the engine dies. I have replaced the jets and float valve. I changed the oil and replaced the air filter. I drained the gas and replaced with 100A% gas. but it has not fixed the problem. any ideas?

 

Did you take the diaphragm,spring and slide and jet needle out OR is it lifting and closing ok with your finger? Have you checked the valve clearance, does fuel pump have a steady stream of fuel to the carb? Also some early models had a habit of the carb partially inserted into the carb intake boot because the support bracket was too far back and would suck air causing lean problems. Fuel pump lines routed correctly?Throttle slack 1/8" only? Just a few things I can think of off hand to check. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

diaphragm has rivets holding it to the carb, so no, I did not check the diaphragm. jet needle was replaced as well. not sure how to go about checking valve clearance. but does have a steady stream of fuel.

 

These are not actually rivets,but tamper proof screws that you can remove and replace with regular metric screws if you wish. If the slide does go up with your finger and comes back down,it's probably not necessary to mess with them.Pull the valve cover and the cam sprocket plate on the right side. Pull the recoil starter slowly and you'll see the intake rocker arms go down and when they start back up again,have the cam sprocket index pin straight up,center of the head. This is tdc. The intake and exhaust valves set at .006. If any need adjusting,loosen the 10mm lock nut and turn the adjuster to get the proper clearance,then tighten the lock nut. If you can't hold the adjuster still ,it make take several attempts to get it right. Best to have two feeler gauges on the double exhaust rocker arms at the same time to keep the rocker arm straight.