Throttle grip size?

My plastic twist throttle grip from the stock 4g 4stroke kit just broke today. where can I get replacements? or can I just go to my nearest motorcycle shop and get one? what size are these? are they the same as scooters? IT broke where the cable end sits. need to find one fast, for the upcoming parades over the 4th.

Got a throttle grip from a 1979 Yamaha 80, worked great. but then I was messing around putting it on and twisted it to far, and pulled the solder crimp right off the other end by the carb. so went and got some lead tear drop fishing sinkers, drilled out the hole to 1/16th threaded my cable through it. crimped it a little and put a cable feral from the bike shop on the end. good as new. and just in time for the parade tomorrow. the worst part of the whole day was trying to get some stainless steel zip ties to stay tight without having the key to tighten them when putting on the heat wrap on the new exhaust I made. I will be doing some measurments on the handles and posting them on here later.