1984 Carb Problem (Dual)

[gonzocolorado]

Hello, I recently purchased a 1984 XR500 and I have a problem with the secondary carb. The bike starts and idles very well. When I ride around on the first 1/3 of the throttle it responds very well. When I go past that position, the bike bogs big time. When I open the throttle wide open, there is a 5 to 10 second hesitation and then the bike takes about 1 to 2 seconds and it gives great response of the open throttle. I have gone through the carb and cleaned it completely and set all settable jets to factory settings. I hope someone has a suggestion.

Gonzo

[roadrunner81]

sounds likes its lean, maybe someone has removed a baffle or installed a different filter. you may want to double check float height and if thats correct try going up two jet sizes on both carbs, see if it gets better or not.

[brichter]

Plugged pilot on the secondary carb?

[keithluneau]

Just a suggestion, but this sounds exactly like what my '86 600R was doing. I was dead set on the carbs, had them off and cleaned them meticulously many times. No matter how much I fought it, the problem wouldn't go away. So then I focused on the ignition, spark was a bit weak anyway. So I change the stator, coil, plug, checked wiring, tested components one at a time, and could find absolutely nothing wrong. I was ready to part it out I was so fed up at this point... 👍 Come to find out it was my CDI box. I picked on up on eBay for $45 new, plugged it in, and it's been like a new bike ever since. Search the forums for bad CDI, you'll find lots of posts describing the same issue with the CDI being the cause. It roots from cold solder joints back when they put them together, and over time the joints break down and let go with heat and vibration working against them.

[keithluneau]

Plugged pilot on the secondary carb?

I'm not positive on the '84 carbs, but I know the 600 dual carbs have no pilot circuit in the secondary carb, only main.