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Common Carb Issues

229142 Views 133 Replies 74 Participants Last post by  latebird
Just trying to get a list of common carb issues for a 2002 TB.

From what I was able to get from the parts guy from the dealer was the following.

- The needle and seat was a common part to wear out which hinders the carbs ability to prevent fuel from back-flowing out and getting into the air cleaner.

- The pilot jet. Mentioned that it can be cleaned but at $6 it is not a bad idea to replace it.

I am currently trying to resolve a car issue I have right now and would love the feedback.

Please let me know of any other common carb issues. Once I get a bunch of isses I can post the issues and cause.
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I have no idea if you guys are talking about a trail boss (4-stroke) or the trail blazer (2-stroke). They are completely different carbs and the 4-stroke one is a lot more complex. I believe it has an accelerator pump in it. I had a guy rebuild the 325's carb because it is pretty complex; the needle and seat are what he said stick a lot and you can't fix it, just have to replace. I'ts been about a year now and I have not had a problem with it. The Polaris replacement parts are about $40 for the needle and seat. FYI, he said on the 325, they will run completely differently if you have an air filter on/off and/or the airbox lid on/off. Here is is website; he is local to me here in Dallas. PolarisATVrepair.com | Local ATV Full Service, Engine Rebuild Services, Engine Rebuild Kits, Clutch Puller, Bearing Kits and more! His specialty is actually repairing/rebuilding 400 2-stroke engines, and people mail him complete engines from all over the USA.

On the 250 2-strokes that I own, the carbs are very easy to take apart and clean. We have 3x 250's, and I have had a 400 Scrambler in the past. One of the float needles leaked after converting the bike to premix, but no big deal.

I have taken all of the 2-stroke carbs apart and cleaned them when I first got the machine. Converted all the bikes to premix at 32:1 with polaris gold oil, and run stabil in the gas. Only use them 4-5 times a year; never had a problem with needing to rebuild the carbs. I've had the 2-strokes 4 years so far.
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My 94 300 2x4 bogs down when I give it throttle, sometimes it will be fine and sometimes ill be giving it half throttle and itll hardly be moving....would this be a main jet issue? Since it happens at half throttle and full ?
I would try putting a new spark plug in it first. They are about $3 at Oreilly Auto.
Generic, no.

My 250 and 400 2-strokes took an NGK BR8ES, I assume yours is the same. Available at Oreilly Auto.

bump...anyone know the part# for a spark plug (94 300cc 2x4). Or are they all generic?
Most likely, the needle and seat are bad or gummed up. (Float needle). The needle is rubber tipped on mine, so it could just be old and the rubber is bad.

Before diving into it, you may wish to try and clean out the carb by adding seafoam to the fuel and running a couple of tanks of fuel through it. I suggest following the can. Don't overdo it, just run 1 or 2 tanks of fuel through the machine.

In the meantime, keep turning off fuel valve when you turn off machine. that will keep it from flooding the engine and running all over your floor.

If you still have the problem you will have to replace needle and seat.

I have a 1996 polaris sportsman 500 and the if the fourwheeler is turned off, and the fuel is still on, fuel runs out of the overflow, i dont know if it has a float or something that is messed up or what?

I have not ran my 325 without the airbox lid, but a freelance polaris mechanic (that I had work on my scrambler 400) mentioned one time that the 325/330's can run sluggish/weird without the airbox top on.

I have a 2003 Magnum 330 that will not take the gas if the air filter is disconnected. Is this normal? It doesn't run well at all until the air box top is back on. Then it still seems to be a little sluggish but will run. I don't plan on running it with the air box off but would like to know if there is a problem lurking before I get back in the woods with it. I looked through and cleaned the carb but it didn't look dirty to start with. Problem I started with turned out to be tank stopped up at the petcock. I guess what I want to know is does this type of carb require the restriction of the air filter and box?
The aftermarket filter will not give you a problem. The uni offers much better filtration over stock paper filter .
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