The Tortoise: cb350 -Now with metal flake

Jan 01/2009

Well, i finally got around to moving the bike to my condo.

The old cb350G single disc front is for sale, as are the tank, seat and covers.

It was a barn find, had sat for 14 years, and with just a tune up and carb clean it fired right up on the second kick.


As of today this is how it sits


it's really quite amazing how simple it was to fit the inverted front on. The lower bearing/race is identical to the factory unit and the upper unit, if you bore the head tube out 1.5mm will fit the same lower bearing. I still need to take the upper tree in to the shop and make a mount for the tachometer, and fabricate new steering stops on the lower tree.

Next project is to design in CAD, headlight clamps and rear sets.

I'm unsure about seat and tank combo yet, i was leaning towards the BCR stuff, but have yet to decide.

Re: My cb350 project

Looks like a good barn find.

Re: My cb350 project

that front end is sexy.
everytime i hear BCR all i can think about is how i would be living on the streets if i bought their products

Re: My cb350 project

more info on the front end ... please and more pics. Im very interested

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.

Re: My cb350 project

Looks like a cool build. I,ll be watching this one closely.

Re: My cb350 project

A little work today on headlight brackets and bike CAD model, just a quick draft so far, but you get the idea.
Hopefully i'll get to the frame this weekend.

Re: My cb350 project

Very nice those brackets look familiar Hmmm have you seen Mysta2's Love the front end.

Re: My cb350 project

IMOALE said:

Very nice those brackets look familiar Hmmm have you seen Mysta2's Love the front end.

Click to expand...

yes we use the same software. Like i said, just a first draft, plenty of changes to come. If I've learned anything from engineering, it's that no matter how you plan and design things never turn out how you've designed them.

It does give you a good idea though.

Re: My cb350 project

I'm Just messing with you bro, I'm actually jelous...I really dig all the cad and cnc stuff and completely have no idea how its done bro. Like I said I really dig you front end LOL LOL I just read what I just wrote.

Re: My cb350 project

some more work accomplished.

Was in the machine shop yesterday and made mounting brackets for these:


I need to make the brake arm shorter, or just make a new one, to make the rear brake function properly.




Next week machining the upper and lower trees. Steering stops and gauge placement.

still haven't decided on a tank, seat or exhaust yet.

Re: My cb350 project

Nice.

Re: My cb350 project

BigBSBusa said:

Nice.

Click to expand...

Uniac,
I have an 08GSXR600 front end which I was going to put on my CB550 cafe project. I think it is pretty much identical to yours. Not being a machinest, I was stumped on how to make this work. How did you determine how much to machine and how deep to go? Is part of that determined by headstock length? What about rake and trail? Will you run 17" or 18" wheels and how do you see that choice affecting handling?

Kemp

Re: My cb350 project

Kemp said:

Uniac,
I have an 08GSXR600 front end which I was going to put on my CB550 cafe project. I think it is pretty much identical to yours. Not being a machinest, I was stumped on how to make this work. How did you determine how much to machine and how deep to go? Is part of that determined by headstock length? What about rake and trail? Will you run 17" or 18" wheels and how do you see that choice affecting handling?

Kemp

Click to expand...

The depth of the bore is dictated by the depth of the bearing race. In this case the 50mm race is smaller by 4mm to that of the standard unit, so you'll have to make a shim. Once pressed in, shim and race, the bearing will sit at the OEM level.

As for a wheel, i haven't decided yet, i still need to locate one. And the cost of these is substantial, so it'll probably be just a stock 600 wheel that i can run dual disc's on for now.

Re: My cb350 project

I had some time to spare on Saturday so i had some fun in the machine shop. I also took delivery of a left hand switch assembly and clutch actuator

I made a mount (.005" fit) for the tach(speedo for now to pass safety) and then bored out the upper tree at 25 degree's. I've yet to weld it in place as i didn't have any tungsten for welding aluminum. So it's just set in place for now.

It's coming along. I'm running out of things to fabricate as i wait for delivery of the wheels, tank, seat, and front fairing. I'm still undecided on an exhaust.

Pics of progress:




Thanks for looking,

Matthew

Re: My cb350 project

More progress than I've been making lately. Lookin' good.

Re: My cb350 project

Mounted the headlight, i made the clamps using a rapid prototyper i have access to periodically. I wanted to see how they'd look on the bike before i committed to having them made on a CNC. They turned out so nice, that i may try to cast them out of aluminum as a side project when it's warmer out.





The process is fairly simple, convert your CAD file to a STL file, crank up the resolution for a finer surface. Pop into the machine. "Print". Once finished and cooled, dunk the printed item in an ultrasonic bath and voila.

The prototyper I have access to, builds up the layers 0.010" at a time, you can sort of see these layers in the picture below.





Not very interesting i know.

Thanks for looking.

Re: My cb350 project

The term "rapid prototyper" and CNC machine make me hate you, in the same way that an ugly person hates movie stars... : )

Re: My cb350 project

I've got a similar project on the go... 81 suzuki GS400. I got a katana front end with the wheel, so I got a 3.5 inch rear to match (GS500). I don't think we'll be able to squeeze it in the little wee swingarm either, which means new swingarm too.....

What about rear suspension? Do you plan on going with bigger rear shocks/springs to match the front end? I'm thinking of that for my project, but no idea what to buy.
Great looking bike!
Steve

Re: My cb350 project

Freakin sweet........