Have a 1988 xr4 that I rebuilt the carbs the spring of 2011. The manual said the carb adjustment was factory set. It is hard to tell if it running too lean because it has the flat plugs( no electro). Is there a traditional plug for this motor? The top of the pistons had a carbon stain with some clean areas,so I replaced the gaskits. The question is ,can these carbs be adjusted.
