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Discussion Starter #1
Hello all,
I am new here and have a question concerning my carb.
Background... I picked up this fourwheeler and it was running well. I damaged the fuel petcock and replaced it with a used one. The used one I purchased had a fuel line I also needed but I did not check it for dirt dobber nests before installing.. Needless to say I filled the carb full of dirt and I started fouling plugs because the needle was not seating. I pulled the carb apart cleaned it put it back together an now the bike won't idle at all but otherwise runs great. I think I might have either switched one of the jets with the idle screw that sits outside of the bowl or I just have it way out of wack. I have been pulling the carb on and off for three hours trying to get it right... any suggestions would be greatly appreciated.

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Be impossible for you to switch jets and mixture screws around. There is an oring and super small steel washer in the mixture screw hole that the screw seals against and the spring pushes against. The oring goes in first, then the washer so the spring pushes on that without tearing up the oring. Then the spring and brass slotted head screw. Turn it in till it is lightly seated or you risk breaking off the tip and having to replace the carb. Then back it out 2.5-3 full turns. That should get you idling good and good throttle response. Many times the steel washer disappears when cleaning one because most don't know they are in there.
 

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Welcome to the board. Nice user name. lol
 

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Pilot jet could be stopped up or the float needle seat is worn out. It should be rounded not squared. It gets square shaped from the needle moving up and down. Remove the pilot jet and clean it real good. A wire from a wire brush works real good for those small holes.
 

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Discussion Starter #7
Well I am an idiot. Looked further into the fuel screw issue and figured out I didn't have everything in the right and destroyed the washer and o ring when I put the screw in. Buying parts now going to put it back together and see what happens

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You're not an idiot. I clean hundreds of carbs a year and I still lose a few of those washers a year. They are very small and become invisible easily. Put the spring, then washer, then oring on the screw, a little wd40 or some type of lube on the oring to help it slide into it's hole and carefully turn the screw in. With a new oring you well have to turn it in a little harder than a used one before it will stop.
 

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Discussion Starter #9
Got it back together still no idle and now it won't take throttle. Cuts out at about 1/4 throttle and then wants to back fire. Any ideas

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Discussion Starter #10
Everything is clean I ran it through ultrasonic cleaner while at the dealership. Fuel screw is at tow turns out

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It has a fuel pump that is vacuum operated. Air box must be fully assembled for it to run right. The fuel pump hardly ever goes out. Only replaced one in the last 10 years of working on over 100 atvs. It is bolted to the frame near the fuel shutoff and the oil tank.
 

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Backfiring like that check for air leaks. Also make sure the gap on the ETC switch gap is set at between 1/16 & 1/8 inch. It's inside the thumb throttle. If all that is ok take a look at the camshaft lobes.
 

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Check the diaphragm in top of carb for holes or dry rot.
 

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This is a bad cam. It was doing the same thing. It has wear on the intake lobe. In most cases the exhaust lobe will wear out. It is the one in the middle.
 

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Here are a few pics with info that might help. Most of the time fuel
Mixture screw is set at about 2 1/2 turns out in this area.
 

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Discussion Starter #19
Thanks for all the info. I ran across a few things in here that i am going to look at tomorrow. I really appreciate all the help and will be sure to let you guys know what the outcome is

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Discussion Starter #20
How do you post photos. I would like to take a pic of the fuel screw and post if what I try in a minute doesn't work to correct my issues. Maybe I broke the tip off when I broke the washer and o ring

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