I have my son’s Honda XR650L on my stand and I am trying to help him get it running properly. It stumbles and pops thru the carb as you will hear in this video. Do you guys think this is a carb issue or is it an ignition issue? It only happens a few times in this video and it is much more noticeable standing next to the bike……

*are the valves in good shape and proper clearance?
*It almost sounds like lean fuel on throttle up.
*plug health
*verify air screw setting.

Sounds like fuel to me. My 40 flatside loves to gum up after sitting a few months.

Thanks for the suggestions. The plug is new and I’ve tightened up the huge gap it had from 32 to 20. I’ll probably adjust the valves….
The previous owner removed the smog box and plugged the lines but he didn’t upsize the jets as needed when you remove the box. So I upsized from 50 to 55 and from 152 to 158 as noted everywhere online. I also shimmed the needle which was also recommended. I disassembled and cleaned the carb in my ultrasonic cleaner. We replaced the slide and its diaphragm. ($125) I will change the K&N air cleaner back to the original foam style. There is a second diaphragm on the side of the carb which I have not yet changed. It supposedly eliminates the decel popping thru the exhaust, but other than that it isn’t typically an issue. I’m not a fan of this style carburetor. 

When my boys were young we rode nothing but Honda XRs. Which is why he bought this bike. They rode thru the XR100, XR200, XR250, and XR600. All of which ran flawlessly and never needed my attention. The XR200 is an excellent bike for riding tight single track thru the trees of northern Michigan. And they were like farm tractors. Keep’m well oiled and they run forever. Then along comes this one…..

sounds like you did everything right. does that carb fire raw fuel as enrichment like some of the flat sides?

btw, here is an old friend from 2003. still have the yellow one.