Those things are a nightmare!!! Stay away! My buddy bought a set for a 750 chopper we bbuildi tried telling him not to buy but he had to have em, now there on the shelf gathering dust. Like strynboen said theres 2 choke levers and 2 idle adjustment screws so any time you adjust the idle it throws the sync off. Those things are nearly impossible to get right, nothing but trouble. And the claim to be better then cr carbs is complete B.S.