I currently have a pull start on my .21 Thunder Tiger engine but the pull start breaks on average once a week and the recoil pullstart is a ***** to fix, I was wondering how easy would it be to fit a drill start system and it it worth the investment?

Thanks

There is a drill stat adapter you can buy that fits most engines that have a 6mm shaft. It is called the Yank ELIMINATOR.
Go to their website to check it out it is avaliable at some hobby shops www.1hg.com