I agree with Robert and Si,
There are thousands of products that your target market would be interested in. Check out Amazon and get an affiliate account.

Get into the mini moto forums and ask questions on

sourcing parts
Tuning
competitions,
suppliers
readers specials
Ect'

and with this information, create a newsletter. I disagree with 3-4 emails a week and feel that this sort of niche, people wouldn't want to be bombarded with emails.

Make sure you don't fall into the trap of promoting stuff just for the sake of promoting something or you will lose people.

They should look forward to receiving your emails and not think "oh here's another sales pitch"