I've had good experiences with Randy at Tri-City Cycle in Waterloo (Weber street), hasn't been without screw ups but he made right on anything I had a problem with.
Closest is Two Wheel Motorsport out highway 6 towards Fergus (just north of Woodlawn), haven't had the greatest experiences with them but it's close and they get parts next day usually. Just down the road from them is Powersport Junction which is a Yamaha dealer, haven't had any direct dealings with them.