I'm not aware of any lakes that have size limits on motors, but on most lakes the speed is 'no wake'. Lakes that have other rules will be posted at the lake. Some lakes prohibit internal combustion engines, in which case you have to remove your outboard and boats with inboard motors are not allowed.
It would be a good idea to peruse the WA state sportfishing regulations. Many lakes have individual regs. These are the 07 regs, but they are in effect until the end of April when the 08 fishing season starts (sometimes later if they're late printing the new booklet). If a lake isn't listed, it means that it is open year round and the standard regulations apply.
http://wdfw.wa.gov/fish/regs/2007/2007sportregs.pdf
Clear Lake allows motors, but is not open year round. It opens at the end of April and closes the end of October.
Don't worry, catch crappie.