Do you think a local dirt bike shop would let me borrow a bike and race for the shops team?

Growing up in a yamaha dealership im sure no one in my family would let you use one of our bikes because of 1) not many shops have race ready bikes 2) not many shops can afford to endorse a rider with the economy low and 3) the odds of the store making profits off your success is extremely minuscule but you can always try a larger company i have several friends who race cross country for Monster energy

show them what u can do on a bike and if u can show them that u have raced motocross and have at least won a race then u have a good shot, but then again i could be wrong go ahead and try though good luck

You can always ask, but I very much doubt it. The way the economy is at the present bike shops are finding it tough and have cut back on just what they will give and do for riders. even if you could get a bike the problem would be that it would not be set up to suit you and so you most likely would not do all that well on it anyway. I know the shop my son rides for helps several riders with parts ect but they only really help two riders every year with major sponsorship and thankfully my son is one of them. But it is hard for even them to make a dollar these days BUt you can only ask

It never hurts to ask, but I doubt it. The shop that I ride for gives me parts and accessories at cost and that is about the best most shops are going to do. I can't speak for every dealer in the country, but I don't know of any racers that get free bikes, even pro level privateers.