I am rebuilding a 75 YZ250B to race and it is close to completion, a harder project than I thought as parts are getting hard to find, I am still looking for a standard size piston but that is not stopping me yet, my problem is the bike has the original sprocket cover or minimal cover if you like but the Regs state I must cover the sprocket? Not use the original setup that everyone actually raced at the time? Unless I fix that I cant race it? What do people use? does DT2MX cover fit onto the bike? All help appreciated.