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Discussion Starter #1
I got kiddo and I a father and son project. Picked up for 500 he already had fresh top end with receipt for boring etc, new chain and sprocket and supposedly rebuilt carb, new starteter and battery. Carb was jacked put together all wrong pilot needle above cable plate no shim etc. Well I fixed and used a sled guy rebuild off ebay and didn't run right. Thought maybe bad kit now tried All Balls and no change. Have to choke but starts right up then idles fine with choke off. When first start can Rev up seems OK. But as soon as gets a Lil warm from 1/4 all the way to 3/4 throttle it just bogs and bellows smoke. It won't move hardly at all. Plug is always wet but not flooding enough to fill case. I'm at a loss is carb shot though about upgrading to flat slide. I took exhaust off to see piston gap in rings wasn't there so that's good lol. I unplugged black wire from cdi no change. I unplugged reverse override no change. Adjusted throttle every which way cause know need freeplay. Adjusted choke all over with no change. Tested compression which only got 120 which seems low but mechanic buddy said the cheapy $20 one I have typically reads low. Have put different floats and lever in and Adjusted from level to down and no change.. But this thing idles great and seems to kick in around 3/4 again I'm lost.
 

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2004 Polaris sportsman 700
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People absolutely hate it when you make two or even three posts in your case about the exact same thing. Someone will see it at some point so just be patient. Anyway it sounds like you’re obviously running rich. Check the pilot jet size that was in the rebuild kit because they are typically never the oem size.
 

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Discussion Starter #3
People absolutely hate it when you make two or even three posts in your case about the exact same thing. Someone will see it at some point so just be patient. Anyway it sounds like you’re obviously running rich. Check the pilot jet size that was in the rebuild kit because they are typically never the oem size.
Sorry I swore I forgot to hit post and phone died. I didn't see on so posted again oops. I did post in xplorer section and the area for repairs though. I will check that out just hard to believe 2 kits I see good reviews on would both do same. Although All Balls kit was trash. The need valve spring collapsed right away so had to use other.
 

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Have you backed your fuel air screw out? Try one full turn out and see how it reacts. How many turns out is your screw currently? In is richer out is leaner.
 

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Discussion Starter #5
Have you backed your fuel air screw out? Try one full turn out and see how it reacts. How many turns out is your screw currently? In is richer out is leaner.
I have messed with it a bunch no change. Out as much as 4 turns maybe. Also tried every clip position on needle
 

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Also 120-130 is good and shouldn’t be your problem. It sounds like the carb to me. Is it a Chinese replacement or do you have the original Mikuni with a rebuild kit?
 

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2004 Polaris sportsman 700
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Have you backed your fuel air screw out? Try one full turn out and see how it reacts. How many turns out is your screw currently? In is richer out is leaner.
Was gonna say this but I don’t think just the air bleed screw would make it that rich and wouldn’t affect it to heavily at the rpms he’s describing.
 

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Discussion Starter #10
Also 120-130 is good and shouldn’t be your problem. It sounds like the carb to me. Is it a Chinese replacement or do you have the original Mikuni with a rebuild kit?
It's an original Mikuni. Still debating a Mikuni TMX or Keihin pwk if can't get fixed lol. Is there any hidden o rings or anything I may be missing. I'm stumped
 

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2004 Polaris sportsman 700
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What’s the seat and needle look like? The o ring around the seat can be worn and just letting fuel in with no regulation.
 

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Pilot jet should be #40 and main jet #155. Having a back blast of fuel makes me suspicious of your reed valve. I checked the schematic and it doesn’t look like it has a reed valve. Ask @latebird he can tell you the problem. No offense but most likely human error in the carb rebuild. Maybe needle needs position change, jet is not the right shape or size, you ran a wire through your slow jet and wollowed it out? One option could be to buy a cheapo Chinese replacement. It comes all together and see if it fixes the problem. Sometimes they work great and sometimes they suck, it all depends on the bike.
 

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Discussion Starter #15
Pilot jet should be #40 and main jet #155. Having a back blast of fuel makes me suspicious of your reed valve. I checked the schematic and it doesn’t look like it has a reed valve. Ask @latebird he can tell you the problem. No offense but most likely human error in the carb rebuild. Maybe needle needs position change, jet is not the right shape or size, you ran a wire through your slow jet and wollowed it out? One option could be to buy a cheapo Chinese replacement. It comes all together and see if it fixes the problem. Sometimes they work great and sometimes they suck, it all depends on the bike.
I have a good running xpress 400 I could throw that carb on to test hoping not to though. Would have to rejet probably since bigger carb. I cleaned nothing as replaced all jets with new. All I cleaned is body etc. Just sucks kiddos excited even got the wheels and tires he picked but won't move lol.
150186
 

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I have a good running xpress 400 I could throw that carb on to test hoping not to though. Would have to rejet probably since bigger carb. I cleaned nothing as replaced all jets with new. All I cleaned is body etc. Just sucks kiddos excited even got the wheels and tires he picked but won't move lol. View attachment 150186
That does suck. You said it starts and idles fine though? Check your magneto pickup for rust. It may need a light sanding to give you a better spark. Also check plug wire and plug for both gap and good strong spark.
 

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I have a good running xpress 400 I could throw that carb on to test hoping not to though. Would have to rejet probably since bigger carb. I cleaned nothing as replaced all jets with new. All I cleaned is body etc. Just sucks kiddos excited even got the wheels and tires he picked but won't move lol. View attachment 150186
I like the idea of trying that carb provided it’s a two stroke.
 

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Discussion Starter #19
Pilot jet should be #40 and main jet #155. Having a back blast of fuel makes me suspicious of your reed valve. I checked the schematic and it doesn’t look like it has a reed valve. Ask @latebird he can tell you the problem. No offense but most likely human error in the carb rebuild. Maybe needle needs position change, jet is not the right shape or size, you ran a wire through your slow jet and wollowed it out? One option could be to buy a cheapo Chinese replacement. It comes all together and see if it fixes the problem. Sometimes they work great and sometimes they suck, it all depends on the bike.
I wouldn't doubt human error lol. Like said guy had needle dropped on top of throttle holder plate. Shim was missing plus various other things like float arms twisted. Could there be hairline Crack in carb from him over tightening something too maybe
 

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Discussion Starter #20
That does suck. You said it starts and idles fine though? Check your magneto pickup for rust. It may need a light sanding to give you a better spark. Also check plug wire and plug for both gap and good strong spark.
Yes idles great and once hit around 3/4 seems to clear and Rev. In-between seems like rpm stays same barely running burning my eyes with smoke. And it's air cooled so not head gasket
 
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