You definitely need to check your fuel pumps it could be #3 is closer and sucking most of the fuel in or it has stronger vacuum who knows but you must check out the fuel pump diaphrams.
sleachrx1
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Sled Dog said:
Will do. At least they are easily accessible..
If there is fuel on the vacuum lines you need new diaphrams.
sleachrx1
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Sled Dog said:
Ok, Gotcha thanks. Your information has been invaluable!!
sleachrx1
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Now if I could just get out of work, to work on it.. Lol
sleachrx1
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Things did not go well today... 
i completely disassembled my fuel pumps, and found no tears, and no fuel in the vacuum line. So i proceeded to completely disassemble the carbs for the fourth time, to quadruple check everything.. All was as clean as a whistle.. But I re did the entire procedure, washing with carb cleaner, then blowing everything dry with blow gun.. On re-assembly, I swapped all the jetting brass and needle valves, floats ect, from carb 3 to carb 4 and vise versa, wanting to see if the problem switched cylinders, if it was still present.. I also made sure the air box was on ALL tha way!!
All this effort was for nothing.. Took it for a ride, about 15 miles, and still had a black #3 plug.. All is good on top tho, 10,200 to 10,500 all day... WTF 
Could I have a valve problem. Low compression? I don't have the proper adapter to do a compression test, but a local mechanic in my area stated that if I had a bent valve, or 1 hanging open for some reason, that it would display these symptoms, as when the rpms come up, it essentially seals the valve on top end.. Now i'm worried, and not sure what to do. I wouldn't think it would pull so well on top, with a cylinder low. Plus, that does not explain the 6 mpg.. And fuel stink.. Help!
i completely disassembled my fuel pumps, and found no tears, and no fuel in the vacuum line. So i proceeded to completely disassemble the carbs for the fourth time, to quadruple check everything.. All was as clean as a whistle.. But I re did the entire procedure, washing with carb cleaner, then blowing everything dry with blow gun.. On re-assembly, I swapped all the jetting brass and needle valves, floats ect, from carb 3 to carb 4 and vise versa, wanting to see if the problem switched cylinders, if it was still present.. I also made sure the air box was on ALL tha way!!All this effort was for nothing.. Took it for a ride, about 15 miles, and still had a black #3 plug.. All is good on top tho, 10,200 to 10,500 all day... WTF
Could I have a valve problem. Low compression? I don't have the proper adapter to do a compression test, but a local mechanic in my area stated that if I had a bent valve, or 1 hanging open for some reason, that it would display these symptoms, as when the rpms come up, it essentially seals the valve on top end.. Now i'm worried, and not sure what to do. I wouldn't think it would pull so well on top, with a cylinder low. Plus, that does not explain the 6 mpg.. And fuel stink.. Help!
I checked my 05 rx1 plugs today and the third cylinder in starting from the secondary as #1 was running black and the reason I checked is because of bad fuel mileage. The only difference is mine is running strong througout I am thinking its a valve and seat leaking running that cylinder very rich. The other day while riding my son said that it would not idle down it idled at 3100 rpm. A friend of mine has a mighty vac tool he is going to check al the valves and seats for me. If this fixes my problem I will let you know.
sleachrx1
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Geesh.. I hope my luck doesn't rub off on ya.. Least you have another mount to ride.. This is my only..:-(
Is that the same cylinder running rich on yours?
sleachrx1
Extreme
Yes sir, it is..
Seems like we are having the same problems but mine is running strong in the mid range just bad gas mileage. Its using twice the fuel my 04 rx1 is.
sleachrx1
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Don't get me wrong, the sled has great performance on top end, and probably mid-range too, but at low end, or idle, it seems to skip like it's on 3 cylinders, and kinda smells rich. The fuel milage is atrocious.. 5 to 6 mpg.. My xcr 800 used to get like 9 to 10, and I thought that was bad, but man would that thing run... Beginning to wish I still had it. Easy to work on.
Going to take it for a good run today but I am pretty sure it was a stuck float needle and valve. It is running much much better but need to test it to be sure. Have you been finding your oil level increasing mine was and it was gas cut.
sleachrx1
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Havent looked at that yet.. Took it to bristol racing to have a compression tens and leak down done.. He can't get to it till next week tho..
Did you sync the carbs? The womans sled was getting 10 mpg and would run good mid and top end power end was not so good. Her plugs were black but i assumed it was a burning oil issue. Now she said it is a different machine. Up around 16 for a mountain sled. The plugs are not as dark. I was ripping the carbs apart 4-5 times a year thing they needed to be cleaned but it turn they needed to be synced up to each other. Hope this helps.