Re: My cb350 project
The front end is an 05 gsxr 600 unit.
The issue with installing the unit is that the factory steering stem on the 350 is 26mm on top and 30mm for the lower unit.
26x48.5x10mm and 30x50x14mm.
The gsxr steering tube is 30mm top and bottom, which makes the OEM lower unit fit perfectly. The problem lies that yes 30mm ID is standard and 48.5mm is a standard OD, but nobody makes this bearing.
This leaves you with a few options.
Option 1 is to grind off the weld from the lower tree/steering stem of the 350, then press out the 600's. Swap and call it a day. However, since the 600's stem is pressed in from the bottom it has a lip to stop it from pulling through. The 350 does not. I didn't like this solution so i passed on it.
Option 2 is to machine the 600's stem down to fit the factory replacement 26mm unit, there is ample room to accomplish this, but it would involve turning threads and metric threads are a bitch to cut on my old lathe, and i'm lazy.
Option 3 is make a steering stem from scratch to fit the factory bearings. Again, too lazy right now to do it, however i can provide a 2D drawing in pdf of such a stem.
Option 4 is to either use a 30x48x12mm bearing up top and fabricate/find a 0.5mm shim OR use a 30x50x14 unit for the top. I chose the later, you can accomplish this 2 ways, take a die grinder and make it as close to 50mm as possible (mixing units, 0.005" to 0.010" below 50mm) or if you have access to a machine shop, take the bike in, affix it to mill, align head tube with an eccentric boring tool and machine the 1.5mm out so the bearing will fit.
I have yet to fabricate the steering stops, or devise a method of ensuring the upper bearing is sealed from the weather.
I'm also contemplating modifying the rear swingarm/suspension to run a single coil from a newer bike aswell.