the disco spud could very similar. what ever it is it is old. it is not in the current line-up. does it have the id tag on the centre section? should be a little tag with model number on it. with this info you can ring an authorised dealer and they will tell exactly what it is.

sorry edit: the point of the spud comment was if it is of similar size then it would be ok for your motor. the air ratios are good but it is hard to tell the wheels sizes in the photo