Brown Stover?

I have a Stover 8 hp KD with 8 25 cast into the hopper. This engine is light brown and no amount of scraping or removing parts has shown evidence of any other color. Is it possible that it is really supposed to be brown? Also I have problems with the spark plug "sooting up" after an hour or 2 of running. I am using a Champion W89D. The engine has a fuel pump and an overflow carb. EK Mag with Type 1 trip. Compression and valves seem good and ign timing is at about 5 deg BIDC. I have to run at about 1/2 choke all the time. This engine is running slower than it's recommended 450 rpm for show purposes but not "super slow" like I have seen others at shows. This is the first "larger" engine I have owned and I have timed the ignition and valves similar to my little Economy. That was good enough to start it but I could use some coaching to get it running better. Thanks for any help or suggestions. SCOTT smootz@zoomnet.net

When you run them slower , they tend to soot up. Go to a hotter plug. Doug.