Jacliny,
bicycle-engines.com/birddog are the importer of Grubee engine kits and accessories in the USA. It seems to be the general opinion that they are good folks to do business with. If they have a fault, it's that they don't respond to e-mail in a timely manner. When and if they ever do respond to an e-mail they always say that they are having computer/server problems but these problems have persisted for over a year+ so if you need specific information/questions about product it's best to phone them.