Hi Hal,
First off, we have a technical packet available that has all the available manuals for the Diablos, the motors, the clutches and the carb along with a few other odds and ends. The packets are $25 which include shipping.
However, there are very few repair instruction manuals out there to help guide you in such a process as replacing sprockets. The link to the gearbox page at gogodiablo.com is below. That will tell you some information.
http://www.gogodiablo.com/?page_id=218
In summary, this is how I would tackle putting sprockets on.
- Remove the hood mount with the hood still attached to it. Drain the gas. Pull the top pin out of the gearbox (may need to pull the secondary clutch off to do this). Flip the unit over and set it on a good pair of saw horses. Your 500 may not have a fill hole in the top of it, but put a drain pan under the gearbox as it may leak oil out.
- Remove the tracks and take them completely off. Unbolt the front nose tin and bumper brackets and remove this assembly.
- Now you can pull your gearbox out. From here, you might consider rebuilding the gearbox as long as you have it out. At a minimum, I would drill a fill hole into the top of the gearbox so you can add about 4 ounces of oil when you put it back together.
- Replace the sprockets. For your 500, the sprocket hubs will be 1" wide. The 502/3 sprockets are 1-1/4" wide. Once installed, I use a center punch and punch around the keyway of the sprocket just enough to slightly cave in the keyway. This stops the key from walking out. Then install the "E" clip.
- Reassemble. Before flipping it back over, install the top gearbox pin and adjust the tracks. I like loose tracks. As long as they do not slap while driving, I think they are tight enough. Both track adjuster bolts should be adjusted so they stick out the same on each side. This ensures the gearbox is square in the chassis.
Does that help?
Bruce
