I hope OPT is still out there... We had tried cleaning the jets in the carb and the fuel float is in the correct position...We disassembled the bowl from the bottom of the carb. took out the float, needle valve and the needle seat. Took out primary and secondary jets, cleaned all parts with carb cleaner. Mild varnish on parts and wall of the bowl Needle was not lodged nor the float.
Assembled carb and installed new carb adapter. Old one was full of cracks, they went all the way through.
Installed new spark plug gapped @ .025. Took along time to start, but finally got it to run...not well. Got it to idle by continually adjusting the large screw at the bottom of the carb. When I slowly increased the throtle the motor would increase the RPM's for a short interval and then POP and hesitate so I immeadiatly decelerated. After many times trying, I watched the intake throat of the carb and noticed that the fuel was building up in the neck and spit out toward the fuel filter box. Then the motor would pop backfire and fumble...Can not figure it out???? Hope someone can help!!!
Thanks
Krissy

 

I would pop the valve cover and check the cam especially if popping and spitting back through carb. Possibly could be the cam exhaust lobe ground down? Sounds like it. Common problem on the older 500s.If the center of the cam(exhaust lobe ) is damaged,I would replace it along with the exhaust rocker arm as it usually gets scored up also. Keep us up dated on what you find. If you don't have a manual,good time to invest in one! Will pay for itself on the first repair. If you need the cam and rocker arm,Cycle Parts Warehouse is about the cheapest I've found on line and definitely cheaper than the dealers! Ordered a cam and a rocker arm for a neighbor through them! OPT

 

yep souns like it's not the carb but maybe a bad cam if it's poppng as mentioned.

 

Thanks OPT I will relay this to Husband... It is a 425 Xpedition I believe it is a 2000 Is that the same info on the cam and exust lobe???
Thanks will keep you informed.
Krissy

 

Does have the same same cam as a 2000 Sportsman 500 and basically the same piston and crank,difference being is the engine cases, internal clutch and transmission on the Expedition 425. Although this model along with the Sportsman 500 shows to have a newer version cam than the earlier models,can still have the same problems. Just check the cam out for damage. OPT

 

opt i am working on a 86 trail boss 250 just replaced the rings crank seals and cleaned carb got fire at the plug and have fuel but wont run or start cant use electric starter becaus it is fried.
replaced stator with a 91 was toled it would work

 

Just by looking at the break down on both machines,the stators are "basically" the same,but the connections to cdi are different,plus the part numbers on the "exciter" coil and main stator are different.How did you "hook" it up unless you have the cdi also? Plus backing up a little,you say you have fire,but is compression good after replacing the "rings",sometimes If you "just" replace rings and piston is worn,won't help that much on compression. Need "a little more info" on what you've done?? OPT