I've been given an old Briggs & Stratton 5hp gennie.I have put a new plug in and taken off the flywheel,this one has no points.I have put clean petrol in but it only likes starting if i give it a spray of that quick start stuff.When its going it runs ok,i havn't had the head off yet to give it a clean up.Just wondering what else i can do,like maybe the carb?There's a good spark at the plug. rob. UK.