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426 sputtering at 1/8 throttle (cruising speed) --any answers yet?


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I've asked this before but has anyone experienced the same problem and found a fix? Runs good everywhere else across the board. 155mj,38 pilot,ekp#3, whitebros. eseries 12 disks. Yes I've messed with the pilot screw to no avail. I think it must be an air jet since nothing helps when changing needle or pilot. 🙂

Chris

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I'm in the process of solving this problem right now.

Out of desperation, I took it to someone for help. I usually don't let anyone touch my bike. I went to David Kelly at Cycle Performance Center in Macon, Ga. "DKR", as he's called, was James Stewart's mechanic the last couple of years that he was an amatuer. My bike had been running fine for a long time... like 2 years. Then it developed this 1/8 throttle syndrone you speak of. I played with the fuel screw... was still rich on the bottom. I could pull my hot start lever and the bike would rev. Went to a 40 pilot and still wasn't right. Went to see DKR. He adjusted the fuel screw... still wasn't right. He pulled the needle to lean it there (3rd from top, now) and went 2 1/2 out on the fuel screw. This made it better, but not quite there. But... while the needle was out, he showed me how it was worn down the sides. He said the jet it went into was probable wearing too... and together, they were causing the rich codition at 1/8 throttle. I got to thinking about it, cause I've never really seen one wear like that, but I've always jetted my son's 2 strokes... and don't know much about these FCR carbs... but the oil in a 2 stroke probably keeps the needle lubed and helps prevent the wear we found. Anyway... my new needle and jet should be in in a couple of days... and I'll let you know if this made a difference. I think it's gotta be it. Can't think of any other thing that would help.

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Thanks for the info and keep me posted. Only thing is that I put in a brand new needle and jet when I leaned it out so I can't believe that it's wearing down after only a dozen rides. Good luck though and I hope it helps. You say it's a rich condition at slight throttle opening? I was told that I should go to a bigger pilot. Oh well, who cruises on a 426 anyway? 🙂

Chris

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I've asked this before but has anyone experienced the same problem and found a fix? Runs good everywhere else across the board. 155mj,38 pilot,ekp#3, whitebros. eseries 12 disks. Yes I've messed with the pilot screw to no avail. I think it must be an air jet since nothing helps when changing needle or pilot. 🙂

Chris

Unless you have already, you need to go smaller on the Pilot Air Jet. This will fix your problem. A stock WR PAJ may work very well with a 38 pilot, but the stock YZ PAJ will be too large, creating a lean condition at low throttle openings and high rpms (cruising speed).

Hope this helps.

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I agree with Hick 🙂

Plus when was the last time you really gave that carb a dushing?

Two things occur on my 2000 426

1: when the filter is getting too dirty it has a bog / hesitation

2: When the carb is dirty or in need of cleaning.

I ride in real dusty conditions and the filter will get dirty in one ride. The crab is cleaned about every 3 - 4 just becouse.

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