UAUS Adjustable Chain Tensioner W/Chain Guide CNC Silver Fit 415 Chain For 49cc 66cc 80cc Engine Motorized Bike Bicycle

Package arrived on time with all parts and pieces. But does not come with bolts long enough to secure everything together. After tracking down the proper bolts, I spent an entire day messing with this thing trying to get it to work. So many problems I'm not going to list them all. But I will say if you use this you will not be able to use a master link in your chain .Unfortunately, this tensioner is complete and utter junk, and I will most definitely be sending it back. For $25 I was expecting a tensioner that was better than the crap one that came with the kit, alas I did not get one, this one may even be worse.Instead of buying a different one and hoping that it works, I ended up just building my own chain tensioner this afternoon. I made it out of some aluminum, u-bolts, and a roller skate wheel. I'll include a picture incase someone wants to use the same design. It's very simple and effective. The only part that is even slightly difficult is groving the wheel for the chain to sit in. ( I chucked it up in my lathe and turned a grove into the wheel, but I'm sure the same thing could be accomplished with a drill and file). Hope this helps any prospective buyers make a more informed decision, best of luck and God bless.

Seems like it may work well enough once I can actually install it. Nice of them to include that bearing, but the lack of instructions left me wondering what it was for quite a while. Plus, they didn't include bolts long enough for me to install it. Now I have to track some down. 😤

An adequate exploded view, and a written instruction are lacking. The only fully assembled photo only shows the product from one side. Pressing in the bearing was difficult. If you are going to have an interference press fit that hard, either press the damn thing in yourself, or make it clear that an arbor press is necessary. It was ALL my cast iron bench vise could do to get the bearing flush. In spite of all that, it is an upgrade. The design is good, the materials and fasteners used are good. I believe there are flatness and thickness tolerance issues with the washers used and the plastic bushing thickness (which to be fair may be just to allow for material removal to match sprocket alignment - no instructions to say so)

I think it's the coolest looking chain tensioner. Be sure to have your rear cog gear well centered on the wheel and don't have too much slack in your chain. To get mine right balance between the engine chain in the bicycle chain tension, I had to get a "half link" bicycle chain link. I might get a hub mounted gear adapter.

Well built and very functional. I wonder how long the billet sproket will last but that my only concern. I would buy it again.

Made to do the job, the ball bearing is to take up slack from the bucking bar, it short shafted the clutch range of motion. had to adjust the primary gear pressure.

The idler arm flexed a little and made my chain touch my tire but I have large tires. Otherwise a reasonable product

Comes with no instructions and the exploded drawing that is in the Amazon listing pictures is not much help either. One thing not mentioned is you will have to replaced the cover mounting bolts with others that are 5mm longer to make up for the thickness of the mount. BTW, the mysterious little ball bearing goes on the clutch cam and rod to add 5mm of length to the actuator to make up for the mount thickness..