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1999 Polaris Magnum 500 4X4 Carb Issues

3K views 5 replies 5 participants last post by  polman500 
#1 ·
I recently acquired this knowing it had carburetor issues, leaking out bottom vent tube. I replaced the carb and fuel pump and now the problem is even worse, leaking out bottom vent tube and fuel coming out of the vent lines on the side of the carb...this is my first atv repair attempt and I'm at a loss, any ideas would be appreciated?
 
#2 ·
New doesn't always mean good. If you are dumping fuel out the overflow, then the needle/seat is leaking, or the float is stuck and letting it stay open. You will need to take it apart and find out which. While you are in there, double check that the jets are the correct size for your machine. Too often on the forum, people have complained that the carb was supposed to be for their machine, but the jets are wrong or there is another issue.
 
#4 ·
A common problem when installing a "new" carb is getting dirt or other debris in the fuel line nipple - that foreign material can get caught in the float needle seat holding it open and causing the problem you describe. Another thing that can happen is; if the carb is actually NEW and not used and just new to the machine, the float can stick down - sometimes tapping on the carb with a screw driver handle ad the carb fills with fuel will fix the problem without taking the carb apart, but if the carb is a new Chinese El Cheapo, the jetting still needs to be checked. While the jetting is supposed to be matched to the flow characteristics of the carb venturi, the Chinese don't always get it right. Many times the importers specify what jetting they want without paying attention to or testing the flow of the carb on a flow bench. Many importers simply specify a venturi size and jetting based on an in use design. Many Chinese carbs don't even have the jet size imprinted on the jets so the size is anybody's guess
 
#6 ·
I've never used one except on the little Chinese machines that you can't easily find parts for. The entire carbs are actually cheaper than trying to get parts for them anyway.
I've never understood why you'd buy a replacement carb except in the above instance?? There's really nothing much to actually wear out. They just get dirty and gummed up and it only takes a few minutes in most cases to clean them up and put them back on. I suspect most that do just want to replace a part rather than actually FIX something. Then they get into the whole issue of having bought a new carb that won't even work for their machine.
 
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