I seem to have a rather nasty problem with my 24HP Honda GX670TDW getting a lot of oil into the cylinders, primarily when letting off the throttle (usually from about 3600RPMs). It's annoying because it's consuming a lot of oil and it makes a fog-advisory grade smoke cloud, looks like a phosphorous bomb detonating. The engine is very new, maybe 12 hours runtime on it. Valve lash is set correctly, I do have rev springs in it.

Any ideas?

Thanks,