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Discussion Starter · #1 ·
First off, I am VERY confident in my mechanical ability. That being said, I can't seem to figure this out, and after a quick internet search it seems there are a few people that have the same problem, but I can not find a decent answer.

I am working on a 325 magnum, 4x4. The running condition before it came to me is un known. When I got it here the over flow of the carb was just running out. I put in a carb kit, and checked all the jets to make sure they were the same size as what came out of it. The owner said that he has had this bike for 10 years, and never had an issue with it, and he has kept regular maintenance on it.

After rebuilding the carb, and double checking everything, the bike starts and runs good. Drive it down the road, and it starts to bog on the top end. If I REMOVE the air box lid, it runs fine, and just the say it should.
I have double checked everything in the carb, and have my air/ fuel mixture screw out 2.5 turns. Thats what the old one was at. everything on the bike is intact, and none of the lines are dry rotted or anything.
I have not checked the plug yet, cause it got cold out side and my wood stove is not complete in my garage.

I am posting this because after my research this seems to be a fairly common problem, and I would like to know if there has been a definite answer. I am pretty sure that it is not the plug, but I will check it in the morning. Thanks for any advice.
Josh
 

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Did you level out the float assembly properly with the new needle and seat? If you have to open the air box you are leaning it out that way. What size main jet is in it? Should be a 142 if stock, and 50 pilot.
 

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How about just removing the snorkel,it may have been cut at an angle that when sit on the seat, this distorts the airbox lid, changing the angle of the snorkel,causing to gasp for air, IT HAPPENS.
Hopefully the sent you the same size needle.
With it neutral, give the throttle a couple quick revs, you should see the slide jump up, the top diaphragms do get cracks in them with age , inspect that as well.
Checlk for good fuel flow at the carb. , it may be time for a fuel pump cleaning and repair.
 

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Discussion Starter · #4 ·
The Float and needle adjustment are set correctly. I am not going to cut the snorkel off on a bike that has ran fine for the last 10 years. I checked all the jets, and the needle, all of them are correct. The diaphram in the carb is good.
Fuel delivery is not an issue, The bowl is staying full, its more like its flooding out, hence the reason that it runs better when the air box lid is removed. The choke is functioning properly.
 

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there is a service bulletin out on some of those older machines where the snorkel actually sucks to the tank my buddys sportsman 335 did that after spending a few hundred bucks he took it to the dealer they cut the end of the snorkel a little bit and boom it was fixed.
 

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Discussion Starter · #6 ·
ok, I have checked the cam, double checked the valve adjustment, new plug, new filter, triple checked the carb, and even looked at the air box lid. None of this has made a differece. So rebuild the fuel pump? something about secondary clutch buttons? how? That will cover just about everything. what else could it be?
 

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You didnt get gas in your oil when needle and seat were bad did you? Need to remove secondary clutch, turn it upside down, remove larg snap ring and spring will push helix out , pay attention to what holes spring was in on clutch and helix, buttons are under helix, its what it slides on, wind spring 1/3 of a turn when you put it back together
 

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Discussion Starter · #8 ·
I am going to try to takle the clutch buttons tomorrow. any last minute advice on what I'm looking for. and can anyone tell me exactly how this works?
 

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Buttons are easy. Remember to rotate the clutch sheave about 1/4 turn ccw to tension the spring before pushing the helix in. Otherwise it's pretty self explanatory once you get it apart. I still think it's something restricting air flow or its jetted to rich. You could try going down a size or two on the main and see if it helps.
 

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New buttons look like a flat mushroom, if yours are worn out, they will be worn down to the screwhead that holds them on, plus the helix ramps will be scarred.
You'll need to file and emory cloth smooth both ramps before reinstall. Spring is usually set at 2& 2.
 

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Discussion Starter · #11 ·
Ridinagain. I thought that it was too. but I don't know what else to check. I have been through everything and the jets that I put in are the same saize as the ones I took out. I turned my air fuel screw out 2 turns, but don't know what it was set at previously as it had been messed with befor it got to me. In neutral it revs fine. and riding it it does fine, unti half throttle. But If I remove the air box lid it does good all the way out.
 

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To set your mixture screw correctly(every engine will be slightly different as far as turns out, that's why the manual states 2.5 turn as a "base",you need to fine tune every engine/carb combo),
First warm the motor up, then set the idle somewhat high(1500-1700rpm)
with the motor idling, reach under the carb with a small screwdriver and slowly turn the mixture screw in till you hear the motor start to slow or run rough(listen closely). Now keep track of where the screw is at and start turning the screw out. slowly!, keeping track of turns , the motor will speed up then start to die down again. Now go halfway between the two or half the number of turns you just counted from when you were turning the screw in , it should be somewhere in the 1/4-1/2 turn area.

If you can turn the screw in all the way and the motor never die down then you need the next bigger pilot jet, opposite if it runs better and better when turning out, you then need a smaller pilot.
 

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only part of the carb that effects over 1/2 throttle is the main jet and the needle that goes into the jet, what notch is the needle set at?, 1-5 notches on top where it sits in the barrel slide, leaner is dropping needle, richer is raising it.

 
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