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05yz450

05 Yz450 Dies At Idle Speed

7 posts in this topic

I have a everything stock 05 yz-450. WHAT CAN I DO TO FIX THIS PROBLEM? If my bike is at idle and I dump a handfull of throttle into it, it just dies. As long as i'm NOT at idle i can give it as much throttle as I want to and there's no problem.

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i had the same problem with mine i calle dthe dealer and told them they told me that afetr it gets broke in the carb has to be ajdust and yamaha will pay fore it so just call and tell them and taht what they will tell u

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i had the same problem with mine i calle dthe dealer and told them they told me that afetr it gets broke in the carb has to be ajdust and yamaha will pay fore it so just call and tell them and taht what they will tell u

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Actually, this is fairly normal. You can do a couple of things to reduce it, possibly eliminate it (search for "bog accelerator pump leak jet"), but mostly, you need to learn three things. One is why it happens. Big four-stroke singles have very poor intake vacuum at an idle compared to two-strokes, and by snapping the throttle open, you are eliminating what little it has and expecting the gas to get itself out of the float bowl and into the carb without any help from the engine. If the throttle is opened even just a little more slowly, the idle circuit is set up to transition the fuel flow to the main circuit, and things continue to work. The carb has an accelerator pump built into it to help cover this "hole" in the fuel delivery by forcibly spraying a shot of fuel into the intake in the hope that it will be enough to keep the engine running until the transition takes place.

The second thing is to learn how to "roll" the throttle progressively. Learn to open the throttle a little more slowly just off idle, opening faster as the engine responds. You'll catch onto it quickly, and you'll find you don't have to take much off the snap to get it to work, and that the engine will respond quite quickly enough for you.

The last thing is that what it does at idle in neutral isn't important. What's the real difference if you can force it to stumble at idle if you try hard enough as long as it responds under way in real-life situations?

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Just bought a new '05 YZ450 & it does the same thing, dies if you wind throttle back at idle speed. Grayracer's advice works for me. If it still bogs when you land off jumps or when you accelerate out of bends you could consider replacing the throttle pump base with one of the larger after-market ones. I did that on a YZ250F '04 and it smoothed out the "burble" that some 4 strokes suffer.

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