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Discussion Starter #1
I have a 2003 Beartracker that idles fine but when I rev it it falls on its face. I've rebuilt the carb with a kit. It didn't help. I thoroughly cleaned the carb. Carb cleaner and air passes through all passages. I'm wondering if the float level is wrong but I don't know what the proper level is. I drained the gas and filled with fresh gas. Anyone have any ideas or know what the float level shoud be. Thanks
 

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Sounds like your main circuit is blocked. Does the choke affect it at all? Is the needle jet secured in the slide? I've seen units come in that have been worked on and the needle will just be floating around in the slide so when you give it throttle it really loads up. Also I know you said you flushed the tank but water is heavier than gas and will go to the lowest place in the system, since the main jet is lower in the carb than the slow jet I've seen machines sit and idle fine then as soon as you get in the main circuit all it gets is water. I'd drain the bowl into a clean cup and be sure you don't have any debris or water. You could also manually choke the unit by covering part of the intake tube in the airbox with the filter removed. If this allows the engine to rev you still have carb issues. Also check for air leaks between the carb and head. I don't think the float level could be off enough to not let the engine rev unloaded. Check all your vent hoses as well. Also an exhaust restriction could do this as well. After you do all that, mix a good stiff drink, I just did...
 

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second for checking for air leaks on the intake manifold. I had a motorcycle with that and it drove me nuts trying to find it.
 

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Discussion Starter #4
I've drained the whole system. When I manually choke it with my hand it revs up fine. The choke on the carb has no effect on the problem. I guess I will ice up the cooler.
 

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wetdirt,
Did you use the jets that came with the kit? The main should be a #95, the pilot should be a #42.5 and the float level 12-14mm. Is it possible to switch jets? I've seen carbs with a choke jet in them that will interchange with the main jet, this can cause weird things to happen. Did you try soaking the carb in carb dip? If you reused the stock jets (which I always try to do) did you just blow cleaner through them or did you push a jet cleaner through them? I've held jets up to a light and looked through them then pushed a cleaner through them and they'll look twice as big. Makes a hugh difference in fuel delivery.
 

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Discussion Starter #7
I soaked the carb. The jets came with the kit and they won't interchange. They are the proper size. Tonight I am gonna check the float level.Something that is strange is the plug is black. You would think if it was starving for fuel it would be white or close to it. I got a new plug today and i'll put it in and see what color it turns. Thanks for the help.
 

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The fact that your choke doesn't change anything either way makes me think the choke is on all the time. This would explain the black spark plug. When you described the problem you said it falls on it's face, does it die like it's just sucking air or does it break up and miss?
 

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Discussion Starter #9
Float is set right. New plug did not help. If you hold the throttle anything over half it dies. No sputter or backfire. If you let it return to idle, it idles fine. If you let it idle for a few seconds it will then rev up ounce like it should. Then the same thing, falls on its face. It seems to me like the main jet isn't letting enough fuel pass to the nozzle. But when you let it idle enough fuel gets by to rev it ounce. So I had a bigger main jet laying around and tried it. Same thing. That eliminates the main jet. Now I'm wondering if it's the nozzle or maybe the needle. If it was one of the tiny passages, I would think it wouldn't rev up at all.
 

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Did you check the emulsion tube (main jet holder) and make sure that the air holes are clear? Also the air passage from the back of the carb to the emulsion tube. We had an arctic cat last summer that would idle fine and when you'd try to ride it it would stumble and jump like a rev limiter. The customer had cleaned the carb, then one of my techs went through it 2 more times. We took the flywheel off and checked the magnets we were so stumped! I ended up sticking a jet cleaner into the air orfice for the main circuit in the back of the carb and it was plugged solid, once I got that clear it ran fine.
 

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Discussion Starter #11
Thanks Carson. I'll try that tomorrow if I feel up to it. Came down with the flu today. Just put my dinner down the drain. Signing off
 

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Discussion Starter #12
Checked out emulsion tube. Looks good. Blew cleaner through it and Vent at back ventri in carb. Cleaner comes out in platic tube that the emulsion tube fits in. I'm back where I started. Thinking about buying a different carb.
 

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Oh...it's one of those with the plastic insert in it. I hate those things. There's two orings on the plastic insert one above and one below the orifice where the air enters the main circuit. I've seen these orings fail, but it's tricky to get to them. For some reason they saw fit to locktite the screws in the carb and sometimes the heads like to twist off the screws... Also they're T20 or T25 safety torx. Meaning there's a neat little peg in the middle of the screw to keep some folks out I guess. This may be a stupid question but you are running it with the air filter and air box lid in place right? I had a 2008 arctic cat 250 in the shop 2 weeks ago that had 150 miles on it and had been at another shop that couldn't fix it. It wouldn't pull it's own weight, but would idle fine. After several attempts at cleaning out the air jet for the main circuit making it better but not exactly right I discovered that the other shop had left out a piece of the snorkle before the air box. I ended up putting a larger main jet in it because the customer had the unit sold and didn't want to wait on the new part. He left happy with the results anyway.
 

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Discussion Starter #14
Is the plastic insert in the bottom of the carb removable? It looks like it is pressed in. The plastic piece that the slide rides in is held in with the tamper proof torx screws. I did try running it with everything together as it should be. Thanks for the help. keep it coming.
 

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Wetdirt, yes all the gray plastic you see is one piece. you take the torx screws out the the whole show comes out from the top. Be very careful with the screws though because they will twist off very easily, they're locktighted in!
 

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Discussion Starter #16
I got the gray plastic out and replaced the o rings. No change. I'm beginning to wonder if I have a vacuum or compresion issue. Checked valve clearance, Ok. Also removed muffler in case if it had a blockage. No change. I don't have the right fitting for my compresion guage. I'm going to try to get one tomorrow to see how much compresion it has.
 

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Wetdirt,
If you had a compression issue bad enough to effect the running this way I don't see any way it would start cold. I know it's driving you crazy but I still think it's something in the fuel system. Have you tried moving the jet needle one way or the other a clip or two? If it's not adjustable you can put washers under it. If you can get it to change, even if it's worse at least you'd know you're on the right track. Just to recap, when you press the throttle it dies? Not misses or skips but dies?
 

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Discussion Starter #18
I put a diffrerent carb on the beartracker. It seems to have improved a little. It used to die when I gave it throttle. Now it sputters and surges. I tried moving the needle. No change. I think I might try a larger jet.
 

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What about a exhaust restriction? If the engine was having trouble getting rid of exhaust then restricting the intake would improve preformance because less in means less out. Maybe take your head pipe off and try it? I know it'd sound awfull but it's something to try anyway.
 

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Discussion Starter #20
New jets should come in tomorrow. If they dont help what about the air shut off valve if the diaphram has a hole in it, would it cause this? I don't see a hole in it. But at this point I guess any thing is possible.
 
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