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Was hoping someone could help me out. Been having troubles with a magnum 425 will start up good after a second or two of idling starts to choke out and smoke from the first set of springs on the exhaust pipe a few inches off the engine. Also as soon as I turn the fuel on it starts leaking heavily from the overflow screw on bottom of carb replaced carb with new one and still does the same, any advice?
 

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Was hoping someone could help me out. Been having troubles with a magnum 425 will start up good after a second or two of idling starts to choke out and smoke from the first set of springs on the exhaust pipe a few inches off the engine. Also as soon as I turn the fuel on it starts leaking heavily from the overflow screw on bottom of carb replaced carb with new one and still does the same, any advice?
inspect clean or replace needle valve and seat,check vents at top of carb,check vac line from carb to pump if it has gas in it the pump is bad. Fluid test carb before mounting . If you need carb call or email.
Thanks Greg 9108851861
 

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Check to see if there is fuel in the vacuum line to the fuel pump - if yes, replace the fuel pump - if no, vacuum test the fuel pump - should hold about 7psi of vacuum indefinitely
 

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Discussion Starter #5
Check to see if there is fuel in the vacuum line to the fuel pump - if yes, replace the fuel pump - if no, vacuum test the fuel pump - should hold about 7psi of vacuum indefinitely
It’s gravity fed fuel would there still be a fuel pump
 

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Discussion Starter #6
inspect clean or replace needle valve and seat,check vents at top of carb,check vac line from carb to pump if it has gas in it the pump is bad. Fluid test carb before mounting . If you need carb call or email.
Thanks Greg 9108851861
I replaced the carb with a new one a week ago would it still be possible the needle is out of place?
 

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90% of Polaris has a fuel pump - I did not view the diagram before I answered - if gravity fed, then no pump
 

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The NEW Chinese POS carbs sold on Amazon and Ebay can have any number of problems - what they sell fits not calibrated for and many have been sold, gotten back and sent out again - I have seen them out of the box gummed up with old fuel or defective in some way - I refuse to install them unless I buy one through one of my trusted suppliers and then all I need to do is adjust it for the engine it is installed on. Certain Chinese carbs (like Sun, Kun Fu and Standard of Japan) have a replacement parts supply, but it is not consistent or reliable. Normally I just drill the jets to get the calibration I need, but it takes so much time I prefer to rebuild the Mikuni carb that came on the quad even if it needs $200 in parts to fix it. When the parts supply dries up, I will resort to substitute carbs, but will stick with Mikuni or Keihin as they are infinitely adjustable.
 

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Where did you purchase your new Carb from? Ebay?
 

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Discussion Starter #11
90% of Polaris has a fuel pump - I did not view the diagram before I answered - if gravity fed, then no pump
But I did have the feeling the fuel wasn’t getting were it needed to go, or something was stopped up at least
 

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The NEW Chinese POS carbs sold on Amazon and Ebay can have any number of problems - what they sell fits not calibrated for and many have been sold, gotten back and sent out again - I have seen them out of the box gummed up with old fuel or defective in some way - I refuse to install them unless I buy one through one of my trusted suppliers and then all I need to do is adjust it for the engine it is installed on. Certain Chinese carbs (like Sun, Kun Fu and Standard of Japan) have a replacement parts supply, but it is not consistent or reliable. Normally I just drill the jets to get the calibration I need, but it takes so much time I prefer to rebuild the Mikuni carb that came on the quad even if it needs $200 in parts to fix it. When the parts supply dries up, I will resort to substitute carbs, but will stick with Mikuni or Keihin as they are infinitely adjustable.
I will have to take apart the new one and see if anything is out of place worse case I do still have the mikuni carb may have to try to rebuild
 

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Was hoping someone could help me out. Been having troubles with a magnum 425 will start up good after a second or two of idling starts to choke out and smoke from the first set of springs on the exhaust pipe a few inches off the engine. Also as soon as I turn the fuel on it starts leaking heavily from the overflow screw on bottom of carb replaced carb with new one and still does the same, any advice?
The 425 does have a fuel pump, look behind left front fender on frame . If the diaphragm is bad it will leak back in to the intake vacuum line in to intake and flood. But sounds like your carb is bad or bad needle and seat. You should rebuild your stock carb like your buddy said earlier the ebay-amazon Chinese carbs are junk , a customer brought one in the other day he got for me to use on his big bear and I took float bowl of to replace main jet and the low speed jet was cross threaded and rung off in it and seen others that the rubber float gaskets would swell and leak etc. the jets are incorrect sizes on them and don't even have size stamped on them,etc stick with stock mikuni its best bet to install kit and check pump etc.
 

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Discussion Starter #14
The 425 does have a fuel pump, look behind left front fender on frame . If the diaphragm is bad it will leak back in to the intake vacuum line in to intake and flood. But sounds like your carb is bad or bad needle and seat. You should rebuild your stock carb like your buddy said earlier the ebay-amazon Chinese carbs are junk , a customer brought one in the other day he got for me to use on his big bear and I took float bowl of to replace main jet and the low speed jet was cross threaded and rung off in it and seen others that the rubber float gaskets would swell and leak etc. the jets are incorrect sizes on them and don't even have size stamped on them,etc stick with stock mikuni its best bet to install kit and check pump etc.
I got to lookin closer after you said that and I did find one on the front under the headlight right behind the radiator cap I imagine that would solve a lot of my problems. But didn’t see any power source or anything is that right?
 

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It runs off vacuum from the carb. Take pics so you get the new one hooked up correctly.
 

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I got to lookin closer after you said that and I did find one on the front under the headlight right behind the radiator cap I imagine that would solve a lot of my problems. But didn’t see any power source or anything is that right?
[/QU it works by vacuum from intake it pulses like a heart check inspect it and float needle valve you can bench test carb before mounting by remote tank until you know its not leaking past float needle valve.
 

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Discussion Starter #19
I will thanks
Well I got a new pump and after swapping it back out and checking the float it’s still steady leaking fuel from the carb I also noticed there was fuel in the oil any ideas where to go next?
 

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I will have to take apart the new one and see if anything is out of place worse case I do still have the mikuni carb may have to try to rebuild
Worse case? Rebuilding the Mikuni is the BEST solution. Worse case is having a novice rebuild the carb, using a cheap 'rebuild' kit with counterfeit Mikiuni parts and the rebuilder damaging something when disassembling, cleaning or assembling the unit. More carbs are destroyed by enthusiastic owner/wannabe mechanics than are successfully repaired.

Well I got a new pump and after swapping it back out and checking the float it’s still steady leaking fuel from the carb I also noticed there was fuel in the oil any ideas where to go next?
Get it repaired by a qualified mechanic unless you have the time and ambition to learn how to do it right.

Starting with the fuel pump - do you have the right lines on the right nipples? If your fuel pump looks like this; are the lines correct?
148608


Are the lines on the carb correct?
148614
 
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