yes its worth it. I have actually have a 5hp tecumseh engine on mine. carb issues are usually minor, just some gunk build up. As long as your not apposed to taking things apart... Also check out the lil 5hp guide, tips to give u more power.
first of all check for spark. Remove the plug and hold it against the block..ect with the lead connected and pull the pull start. watch for spark. A good spark is blue in colour.