Motorcycling Australia in late 2003 changed the rules in relation to Junior up to 125cc 4 strokes.
They effectively banned the modification of the bikes and restricted them to natural terrain.
You have an interest in motocross and most likely have modified your bike to suit your rider. Maybe you have had the suspension set up, put on good handlebars, changed to a good brand of brake pad. Simple things that make your bike more reliable and better than stock.
If you have an "A" grade rider you probably have spent a lot of time and money making the bike better and a lot faster than stock.
Do you want to ride a completely stock bike. Even to the grips and tyres?????
It appears that for 2004 Junior up to 160cc 4-stroke bikes cannot have even these simple things modified.
You dont ride that class so you dont care?
You never know what might happen to your class if you dont do something.
Send an email to Motorcycling Australia opposing the changes and asking them to remove the changes.