On the YZ400f head on the left side, there is a hole. Is this supposed to be plugged with a soft plug or something? Is it an overflow hole? When I start my 400 I let it run and after running for a bit, coolant starts to come out after I shut it off. Not much but alittle. I just replaced the cylinder and am curious if this is normal due to to much coolant or if it is something I should take a look at. Thanks.