Need help. Lately, my xr650r is stalling. When I come to a stop it may idle fine, but usually just burps and dies. It then takes atleast a few kicks to start back up. Also, if I let it idle for a few seconds then quickly blip the throttle it will burp and die. I suspect it is too rich or too lean, I just don't know which. The mods to this bike are 16211-mbn-640=opened carb intake, #170 main jet, and #68 jet, and uncorked muffler. The bike has just developed this problem and have not had any issues before. I live in Dallas and temps have been over 100 degrees. I have raised the idle to keep it from stalling at lights while I find the real problem. Also, when running about 80+ sometimes it will "pop". What do I adjust and what direction. Thanks for you help. I searched for a helpful link but couldn't find one.