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yammx

Throttle response

7 posts in this topic

Another little bug in my 650,

after coasting from a higher speed an entering a corner when I am accelerating it feels like the throttle is stuck from full close.

So, it is not possible to open the throttle smothly. Especially in thight corners on pavement with my knobbies, i have always a sliding rear wheel.

Is there a solution? Will a carburator adjustment help?

Please let my know!

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What is happening is, the strong intake vacuum generated by the 650 is holding the throttle slide against the slide bore. When you open the throttle, the friction between the slide and the bore causes the slide to snap open quickly rather than opening smoothly. As the slide and bore wear, the problem becomes more severe. Other than a new carb (or maybe new slide), the only suggestion I can offer is to put a few oz. of two stroke oil in the gas, this will provide some lubrication for smoother slide operation. I used to do this on my XR600s, they were famous for the "pop open slide". Hopefully, someone else on the forum might have a better solution.

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Try raising the idle and set it richer at idle to get the slide up more (less decel vacumn)

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What is happening is, the strong intake vacuum generated by the 650 is holding the throttle slide against the slide bore. When you open the throttle, the friction between the slide and the bore causes the slide to snap open quickly rather than opening smoothly. As the slide and bore wear, the problem becomes more severe. Other than a new carb (or maybe new slide), the only suggestion I can offer is to put a few oz. of two stroke oil in the gas, this will provide some lubrication for smoother slide operation. I used to do this on my XR600s, they were famous for the "pop open slide". Hopefully, someone else on the forum might have a better solution.

Good explaining,thanks. But I forgot to mention that I have also heavy banging while coasting. So, that means bottom is to lean. Will a pilot screw adjustment help or do I have to swap the slow jet?

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Good explaining,thanks. But I forgot to mention that I have also heavy banging while coasting. So, that means bottom is to lean. Will a pilot screw adjustment help or do I have to swap the slow jet?

Popping from the exhaust on deceleration indicates a lean pilot (slow) jet. You might be able to improve the situation by backing out the fuel screw. If you have to back the fuel screw out more than 3 turns or so to get a proper idle mixture, the pilot is too lean.

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I've heard of drilling a small hole somewhere on the slide.?? Never tried it myself. Mainly cause it didn't make much sense..

The premix thing sounds like a good idea.

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