Topic: Barn find café build

[Clarifixer]

Hi Folks--

I had this posted in the general category, but thought I'd better start again in the Project section before it got too far along.  The bike: a 1973 CB750 barn find with only 4459 actual miles on it.  It sat for thirty years, but it does start and run--sorta.  There's the usual rust, corrosion and boogered fasteners, but I'm looking at a frame up build, so it doesn't matter to me.  It's like a low mileage engine with bike attached.  I took off a very silly sissy bar that came on it originally and sprayed every nut and bolt with PB blaster for three days. 

It's tough parceling out the time to work on it, as you all well know (that old J-O-B just gets in the way), but I have the exhaust partially off and am whittling away at the disassembly. 

More pics and real progress to follow.....

[Clarifixer]

I knew I wanted a SOHC 750 some time ago, so I have been collecting parts from a '76 GL1000 front end in anticipation of the event.  I like the idea of the twin rotors, larger diameter fork tubes and four bolt axle attachment, and thanks to the flow of knowledge from many here, the fact that it bolts right into a K3.

So far I have the sliders buffed (picture is a comparo of stock and polished) and the top triple tree.  What a scutt job that is.  The tall risers were left as is for now with the thought that I'd bring the fork tubes up about 30mm proud of the triple tree and use adjustable clip-ons on top.  Maybe then I'll fabricate a plate that will bolt to the risers and house the warning lights and ignition switch??  There'd be plenty of room underneath for wiring.  What fun to plan!

[Barossi]

Wow, that triple tree turned out great!! I'm in the process of stripping the paint off of mine and am debating whether to repaint or polish.

What did you use to sand/polish?  Dremel?  Must have taken forever

[Clarifixer]

Man, it was TEDIOUS.  I had to do a lot of sanding (someone here had a great tip about using the sandpaper with adhesive backing so you can concentrate on rubbing rather than grasping the paper) before buffing.  The areas around the drillings are a b*tch because you can't get a good stroke going.  Bigger areas are a relief by comparison.

Buffing was really just the last hour or so.  Lucky guy that I am, I have a home-made buffing machine, so you can use your whole body to lean into the work and manipulate it around.  If you have a lot to do, it's a great thing to have, but it can be dangerous.  Be careful of the wheel grabbing and watch for flying parts!

[Clarifixer]

I just got my rotors (for the GL1000 front end) back from Scott Woodruff and I am absolutely gassed.  His work is really GREAT and communication first rate.  I couldn't believe how efficient he was on getting them back--just a matter of a few days.  I asked for a mirror image on the rotors for looks, with a slight chamfer on the holes and he gave me exactly what I wanted.  Thanks, Scott!

[Really?]

Looks like you have a good head start.  Bet this turns out nice.

[The_Crippler]

I asked for a mirror image on the rotors for looks, with a slight chamfer on the holes and he gave me exactly what I wanted.

Man, I really wanted to get that pattern done on mine, but it was just a little too spendy for my budget...I got one of his more modest patterns done instead, and it still looks fantastic.

Great start on the project.  Looking forward to seeing where it goes.

[Clarifixer]

I asked for a mirror image on the rotors for looks, with a slight chamfer on the holes and he gave me exactly what I wanted.

Man, I really wanted to get that pattern done on mine, but it was just a little too spendy for my budget...I got one of his more modest patterns done instead, and it still looks fantastic.

Great start on the project.  Looking forward to seeing where it goes.

Yeah, I know what you mean.  I've been doing a lot of sighing and eyeball rolling, too.  As my dear old dad used to say, "The pain of purchase soon dissipates."  I've wanted to really go for it on a custom machine all my life, either two wheels or four, and two is much more affordable.  At 62 and after a few false starts, I figure this is the last chance I'll have for a full tilt boogie.  We shall see...

[The_Crippler]

Ha!  I like the cut of you jib, sir!

[Clarifixer]

If anyone has fiddled with this and has some more ideas, jump right in.  I hate pitfalls.....

I've been continuing the work on the front end of the bike and have acquired springs from Race Tech and their Gold Valve emulators to take the place of the stock damping rod system.  I had to do a bit of machining on the old damping rods--the emulators take the place of the original compression holes, so you have to chamfer the old holes and drill appropriate new ones.  Rebound holes stay the same.  

To set the preload with the emulators, you have to machine spacers (aluminum tubes with steel washers on the ends) between the top of the spring and the top cap to match the weight of rider and bike.  Of course this is an art rather than a science since some riders like quicker turn-in or softer bottoming, etc., and I'm new to this.  I decided to make adjustable spacers utilizing aluminum, but with a stainless steel socket head cap screw (M12 x 1.75) for adjustability.  This picture is of it loosely assembled--the bolt head end gets tightened into the top half with Loctite 271 red threadlocker.

Since the pictures were taken, I have decided the set screws were not enough, so I am using a thin jam nut in between the two halves and machined wrench flats on the bottom half to help seat it against the jam nut.  Of course now using the set screw will be like wearing a belt AND suspenders on your pants!

The M12 x 1.75 bolts were quite heavy, so I machined them down and saved 16.2 grams per bolt. Note the drilled out center the entire length.  The bolts are in compression and not shear, so strength should not diminished.  Eh?

With all the new parts I am saving approximately 1/4 pound per fork tube over the stock springs as well as having a modern cartridge-style damping system.  Hey, it's half a pound less for the engine to propel.

It is not on-the-fly adjustable, but with the GL1000 forks it shouldn't be too bad. If I want to change the length of the spacer, it's "just" a matter of taking off the top caps, removing the spacer and changing it's length with a couple of wrenches and putting it back in.  It can be done without having to take the fork tubes out or anything so it is relatively quick.  Of course I haven't had to do that yet, so it may be a P.I.T.A. and more involved than I think.  Anyone familiar with this process?

[theofam]

I think I'll use your dad's "the pain of purchase soon dissipates" on my wife next time she questions why motorcycle-related paypal entries dominate our monthly credit card statement!

The build is going well. Looks like you've a great setup with the blasting cabinet and polishing wheel to turn out really nice parts.

[cdoggy81]

This should be a cool build. I like the direction so far!