Bike to not runs on full choke. Rebuilt the carbs but didn't fix it.

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Bobdag

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• Jun 10, 2015

• #1

Like the title says. The bike will only Dunn with the choke all the way out. By the way it's a 82 Yamaha 400 special 2 (400xs) the bike ran great before I parked it a couple years ago. I cleaned the carbs and had it running somewhat. I replaced the intake boots and did replaced the needle and seat, I set the floats to 1.25" as per the manual. It only runs with the choke all the way on. If I give it gas it cuts out then revs. The rpm's fluctuate at anything above 2000rpm. Any thoughts as to what it could be? Btw I checked and replaced vacuum lines and the crank case vent tube.

 

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Bobdag

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• Jun 10, 2015

• #2

Wow! My auto correct hates me!

 

ScottLuke

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• Jun 11, 2015

• #3

sounds like it needs to be re-jetted. have you checked the plugs, what have you changed?

 

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Bobdag

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• Jun 11, 2015

• #4

Plugs are new, cleaned all the jets with a torch tip cleaner, I didn't open up the vacuum diaphragm's because they moved freely. I might need to check them for tears tho.

 

Scorpio1963

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• Jun 12, 2015

• #5

Take the carbs apart and clean then thoroughly.Then sync them

 

XSLeo

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Lebanon NY

• Jun 12, 2015

• #6

Torch tip cleaner? Those are mini round files. Probably enlarged the holes through the jets.
I would tear down your carbs and replace those jets.
I have very good results with just spray carb cleaner and air. If things are a bit tough I might use a twist tie from a loaf of bread, peel the cover off about a 1/2 inch on one end. This leaves a fine soft wire to probe things a bit. It won't hog out the holes bigger but will punch through the crud enough to get the cleaner to work. I then go back to cleaner and air.
Leo

 

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Bobdag

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Ellensburg washington

• Jun 13, 2015

• #7

I only used about the first half inch of the tip. There's no grooves on the tip of them. The old gas was varnished to the point of being almost jelly. I think I found the issue tho. The air filters are plugged solid! Ordered new ones yesterday. Hopefully that helps so I can get it dialed in.

 

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eric123

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• Jun 15, 2015

• #8

Do you have stock exhaust and air cleaners?

 

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Bobdag

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• Jun 17, 2015

• #9

Stock exhaust and air filters. Replaced the air filters and got it running good! But! Now it looks like it's burning oil on the right cylinder. It's smoking like cheech and chong! Not sure if I got a bad ring or a valve seal. It has valve seals right?