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Discussion Starter #1
I bought this sled over the summer with not quite 7000 miles. The problem is that when i started riding it this winter, it seems like a cylinder is missing at only 4500 RPM. It idels good and drives good at all other rpm's, its just when i take off slow that it always is boggy at about 4500 and as soon as it gets past that speed it takes off rerally fast. Could it be a carb problem or a clutch problem, or anything else?
 

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You better get used to it because i have a xc 600 and it has the same bogg to it and i tried everything and found out it is the the way they are.Mine would bogg taking off but if i came to a stop for a second and then took off it wouldnt bogg they say it is loading up on fuel because they run rich from factory hope this helps
 

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I know the 01 500 xc sp's had trouble with the throttle positioning sensors on the carbs. They need to be set at such a voltage, and if they arent they can make the engine work badly at certain rpm. I dont think your 99 has it though...if it does, there should be a little electrial thing on the mag side carb.
 

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Discussion Starter #4
Sorry haven't been able to get on here since. Thanks for the posts, i was just making sure that there wasn't anything wrong with it. I've put almost 200 miles on so far this year and it hasen't changed, most annoying part is crossing roads.
 

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Discussion Starter #5
I forgot to add this on my last post- does anyone else with this kind of sled have a problem like this because i don't really see any other postings that mention anything that could relate to my possible problem?
 

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Trevor
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Take an air chuck and blow our your clutches. They may even need to be rebuilt. If they are original I bet the rollers and other parts are worn out. Could be a broken reed, gummed up carbs, bad belt, or anything really.
 

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Discussion Starter #7
Thanks i appreciate the help. I will check out the clutch this weekend, the belt looks brand new, and the carbs were cleaned before it was ridden this year.
 

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Discussion Starter #10
So I cleaned the primary clutch but that didn’t help. It was diffidently a misfire that was going on always at the same RPM speed. After searching around I took apart the carbs to make sure all the stock jets were in it, which there were, and I ended up adjusting the pilot screw to be a bit leaner because it stunk pretty bad when idling like it was too rich. Through out this whole time the plugs were always a perfect brown color. That didn’t help at all so I went back and dropped the needle down one groove and now it runs almost perfect with very little misfire. Just needs a little fine tuning yet. I wanted to post how I resolved this issue for anyone else who may have problem like this with there XC (they ran from factory to run very rich).
 

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I have a 98 xc 700 just started doing the same problem. low end bogg goes like hell after that seems like its a carb issue. It seems like its starving to ide. Doesnt idle normal. Plugs were wet. I noticed when I took the air box off one of the carbs was spitting out gas when you gas it the throttle dont know if thats normal.
 

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98 had issues with the coil/cdi one cylinder will start to lose spark.the spitting gas is normal the carb that isn't spitting is the problem cylinder either no spark or weak spark or no compression.usually if it was the coil it would run ok when first started then when the coil gets warm it would act up.try putting your hand over the carb see if its sucking if not then more than likely your piston is junk.do a compression test.
 

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Did the hand over the carb thats all good, what I did notice is that I lost all my fuel. motor was full had to drain it. so then I played with the shut off when there was little fuel in the carbs it ran great so much better so much more power even sounded better. Both carbs were running together. So now Im thinking needle seats?? and float adjustment.
 

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just the right side, Im thinking its a ruptured diaphram in the fuel pump. Im going to pull the line that goes to the motor and see if fuel is flowing into the motor. Its funny because when I played with the shutoff and cut the fule off after about 30 seconds it ran great but as soon as I opend the shutoff it flodded out, but only on the right side.
 

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It was funny because it was running pretty good and all of a sudden it ran like crap, so you know how it goes do this do that clean clean clean. Now I can clean the carbs with my eyes closed...lol The big thing was when I lost all my fuel on the garage floor. not good. And its got the fuel pump that mixes the oil in the pump. Lucky an extra one came with the sled so ill change it this morning. But in curious to see what is wrong with the old pump. Im going to take it apart buy a rebuild kit for it. And its got the carbs that are noted for the loose float pins, these are still pretty tight.
 

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So I cleaned the primary clutch but that didn’t help. It was diffidently a misfire that was going on always at the same RPM speed. After searching around I took apart the carbs to make sure all the stock jets were in it, which there were, and I ended up adjusting the pilot screw to be a bit leaner because it stunk pretty bad when idling like it was too rich. Through out this whole time the plugs were always a perfect brown color. That didn’t help at all so I went back and dropped the needle down one groove and now it runs almost perfect with very little misfire. Just needs a little fine tuning yet. I wanted to post how I resolved this issue for anyone else who may have problem like this with there XC (they ran from factory to run very rich).

check you wiring going from you stator to the coil pack for your plugs mine was having a massive missfire and backfire it turns out 2 of the wires were boken and was causing one of the plugs to go on and off sending it to over fuel and then backfire leading to a massive bog,
 

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Discussion Starter #19
So does your sled run good now 99xc500sp? I thought that the problem was solved on mine, but it is not. I believed I ruled out the electrical system, all the ohms were in spec. I ran it recently but had the track off of the ground instead of driving it. Still does the same thing, If push the throttle about 1/4 of the way, the track starts to engage and then it starts to bog. As soon as the track engages around 4000 rpm it bogs, the rpm's drop down a bit and then it takes off. It doesn’t matter if I push the throttle more or keep it at the same position, it always bogs down to around 3500 rpm and then shoots up with no misfire and runs perfect. The Sled was warmed up. I’ve tried a bunch of combinations but it hasn’t changed - Needle is currently on the 2nd notch down from the top, pilot screw is at 1.5 turns. It is loading up on fuel? Ideas…
 
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