- Sep 22, 2000
I have a 96 XR 400 with a mukini pumper carb and XR's only exhaust. When I let off the gas, while riding, the exhaust pops quite a bit. The plug looks fine so I don't think the bike is running lean. Is this just a fact of life for some 4-strokes. I've heard other 4-strokes make the same sound while off the gas. Is this something I should be concerned about? The bike runs strong other than the annoying popping noise.