Re: CB750 No Plunger Hellride
I took some time off from working on the Mid-Ohio haul to make the chain tensioner. I machined the drum and welded an old gear shift lever to it and a cap screw to the shift lever. I machined a bronze bushing to insert into the drum, then on the backside I machined a delrin bushing to fill around the bronze.
In all but the last pic, the arm is basically straight. In the completed unit, I bent an "S" into the lever which centers the skateboard wheel over the pivot and moves it clear of the frame.
In this pic are all the components minus the spacer to go behind the skateboard wheel that centers it to the chain.
This is the backside of the tensioner, where the delrin surrounds the bronze.
Here's the unit put together with the spring from a kickstart mechanism. One thing that changes on the spring from what you see in the pic, I spread the first coil out to help put more tension on the spring and to help it spring back a little better. That may not have been necessary, but it doesn't hurt either.
Another view of the arm and pivot. Notice the drum isn't machined square, but instead has a curve to it. This helps the spring move toward the arm and keeps it from binding in front of the mechanism. It also gives it more throw, as the way the spring works the ID shrinks when the tensioner actuates. I didn't want the spring too loose, but too tight kept it from swinging very far and it would bind.
This is the pic of the completed tensioner. The arm is bent, which moves the wheel back toward the center of the bike. The arm is also shorter than in the previous pics.