Noise, if you enter it under "parts" or "spares" then it will only list it in that category, make sure your in the vehicles section before you move out of the first part of the listing, sounds like you have selected the wrong section, when you say sell and select the item description then you get the option of either parts or vehicles, looks like this
Cars, Motorcycles & Vehicles
Motorcycles & Scooters > Yamaha
Hope that helps mate?