The Junior class for 2007 is limited to Honda CBR150 motorcycles supplied by Honda Australia. So probaly your first point of call should be one of the authorised Honda dealers. These are:
Sydney City Honda Lane Cove NSW
Sydney City Honda Liverpool NSW
Red Wing Honda Melbourne VIC
Brisbane Motorcyles Brisbane QLD
You should refer to the rules under the Racing tab on this website to see what you can and cant do to the bike. Basically you can not touch the engine, chasis or suspension. We are trying to keep the class as cheap and even as possible.
For tyres we would recommend that you go and see Craig White at Whites Racing Products for some Bridgestones. You must use treaded tures and Bridgestone do some nice sticky ones at an attractive price. Craig is definitely looking after us here.
With leathers we would recommend that you go and see GiMoto leathers at www.gimoto.com.au . Rory has sizes designed for Juniors which is a big plus. For an alternative try Laro Leathers at www.laro.com.au