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clark4131

Fuel Screw & Carb Issues

22 posts in this topic

Here are the symptoms:

Installed Zip-Ty Fuel Screw on my '05 WR450 last night. There was NO O-Ring that came out with the OEM screw and there wasn't one stuck inside the carb upon inspection. I did see what looked like a small washer, so I'm assuming it was holding the O-Ring on the other side of it. Turning the screw in either direction has NO effect on performance. I inspected the screw and it is not broken, bent, etc. Do I need a smaller pilot?

I also installed the JD Kit with the Red Needle on #4, 165 Main, 72 Starter, 42 Pilot and 70 Leak. When I crack the throttle fast, the engine immediately dies. If I crack it not quite as fast as I can, no problems. I have a 48 Pilot and 40 Leak on the way, will that help?

So there you go. The Fuel Screw thing has me baffled...how can it do nothing? I think the bogging problem may be the Leak jet and perhaps the needle position, but I'm not positive. I have good power after 1/4 throttle, so that's what's leading me in that direction. Thanks...SC

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the #40 leak jet should definately help with the bog. If that dosen't quite do it try a search on the bk mod. I had to hit my carb pretty hard (with my hand of course) to get the rubber o-ring out of there. I would leave the carb the way that JD suggested until you try that leak jet, more than likely it will fix the problem. :)

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That's what I thought, but what about the Fuel Screw thing? That ought to have some effect on the bike's performance even in stock form, right?...SC

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You need to find the o-ring :) The motor should die with the screw all the way in and a JD red needle. Mine runs perfect with JD Red5, 45 pilot and stock leak jet. Without the o-ring your sucking more oxygen into your mix, you would need a 55 pilot before you noticed a change :p Find the o-ring before changing pilots and leak jets.. :)

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Based on the carb diagram, the o-ring is behind the washer which was still up in the carb when I looked at it. When the new jets arrive, I'll pick up a new o-ring as well just in case...SC

UPDATE: I just took out the Zip-Ty and the washer came out on top of the spring, but still no O-Ring. I got the bike warmed up and started to fiddle with it and here's what I found: When I turn it 5 or 6 turns out it starts to die. When it's all the way in, it runs much better. I'm so frickin' confused :) ...SC

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Steve Your Never Going To Get Your Jetting Correct Without The O-ring Sealing Your Screw. My Screw Fell Out One Day In Doyle The Wr Had Problems All Day . Kirk At Michales Can Get You A New Screw,o- Ring Not Sold Seperatly.good Luck Keep Us Posted.

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I got a new O-Ring from Kirk just a couple of hours ago. I'm going to tear into the carb tomorrow and make sure the original one is not stuck up inside. I'm hoping it's gone, which would then explain my problems somewhat. If it is in there, then it's back to the drawing board. I did get the little washer to come out with a couple knocks on the side of the carb so we'll see...SC

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I have 05 with the airbox, exhaust ,throttle stop,gry wire mods done. bike dies when i open throttle all the way. if i roll the throttle i don't have a problem/

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Steve Your Never Going To Get Your Jetting Correct Without The O-ring Sealing Your Screw. My Screw Fell Out One Day In Doyle The Wr Had Problems All Day . Kirk At Michales Can Get You A New Screw,o- Ring Not Sold Seperatly.good Luck Keep Us Posted.

Who is Kirk at Michaels? I think I need an o-ring also

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The pilot circuit gets you about five feet, then your on the needle..Try the red needle on five, about the same as blue3 on top. Also switch to 168 or 170 main. See if it idles better with a touch of hot start or choke, this will tell if your rich or lean..Good luck

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I am riding with #DTR-4 needle, #48 pilot and stock leak jet without problem.

Good luck

05WR450F

04YZ250WR

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Kirk is one of the parts guys. They all call him "Capt. Kirk". He's about 5'7", with red hair, a goatee, glasses, probably early 40's. He really seems to know his shiznit..SC

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You really have to look for that oring when it sticks in the carb. It is very hard to spot. The shadows sometimes hide it when you shine a flashlight up it. If it fell out when you removed the screw, of course it is gone.

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Here's what I'm running now...

168 Main

48 Pilot

72 Starter

70 Leak

JD Needle Blue #3

Alititude: 4500-6500' ASL

Temp: mid 50's - mid 60's

I have great power and response from 1/4 throttle on, but am still getting a little bog off idle if I crack it too fast. I'm waiting on a #40 Leak Jet to hopefully cure the bog, but they're back-ordered right now.

The thing that's got me confused is that the Fuel Screw still does nothing! I have the spring, washer and O-ring now, so that's not the issue, and I've never forced it to seat causing any damage to it. If I turn it out more than 2 turns, the engine starts to die, but it runs great fully seated. Do I need a smaller pilot like a 45 or 42 or even smaller? Please God, help me :) ...SC

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Try the 40 leak jet. In the mean time you can take the stocker and silver solder it shut :)

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Sounds like too big a pilot jet to me....I've got a 45 in my WR, and I'm at 2500'.

Here's what I'm running now...

168 Main

48 Pilot

72 Starter

70 Leak

JD Needle Blue #3

Alititude: 4500-6500' ASL

Temp: mid 50's - mid 60's

I have great power and response from 1/4 throttle on, but am still getting a little bog off idle if I crack it too fast. I'm waiting on a #40 Leak Jet to hopefully cure the bog, but they're back-ordered right now.

The thing that's got me confused is that the Fuel Screw still does nothing! I have the spring, washer and O-ring now, so that's not the issue, and I've never forced it to seat causing any damage to it. If I turn it out more than 2 turns, the engine starts to die, but it runs great fully seated. Do I need a smaller pilot like a 45 or 42 or even smaller? Please God, help me :) ...SC

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Seabass Kirk Is The Guru At The Local Yamaha Shop In Reno!

If only I lived in Reno! My local Yamaha shop gave me a new o-ring and washer.

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