Just had a guy come it with free spinning drive sprocket. Been seeing a lot of these on the boards lately, but none at my shop. I don't know what kit it is, but it has a gold sticker on mag cover saying 'not for road use' according to EPA. Went to put a key in, and found why it was bad. All motors I've seen always had all four keys matching in thickness (either fat keys or thin keys). This motor has slots cut for fat keys, but all attaching parts had slots cut for thin keys. This lets the key fall out or even turn a bit sideways and get sheared off. To keep repair cost down, I used a bit of steel in the slot to hold a thin key a bit higher and tightened it down well. Looks solid now, but will re-post if it fails at some point over next couple weeks.