Just One Glazed Black Spark Plug? But No Smoke

[bazil_205gti 22]

HI this is on a new engine i have read this could be due to either valve seats or piston rings? but usally you get smoke due to the oil but i dont seem to have smoke. canthis happen with new engines? or does it sound like something isnt right i have around 300 miles and run the engine in following some advice off here.

 

any feed back would be very helpful

 

thanks

 

Matt