This is a post that is long overdue. Sorry for all the text, but hopefully someone finds some of this interesting or useful.
Last May (2017) I picked up my first motorcycle - a 1977 CB750F - for $250. Having never touched a bike before I was excited, yet intimidated, by the prospect of making this bike my own. When I bought it, I was told the bike had a title, but that I would have to pay backtaxes to get it. Turned out that wasn't the case, but according to Kentucky, I should be able to obtain a rebuild title for the bike when it's finished.. or so I hope.
Anyway, here is what I took home that day for $250:
On the surface, she looked great. As I expected though, there was a lot of work to be done. I wanted to go the often-travelled route of doing a cafe build. I wanted to modernize the braking an suspension to improve handling, tidy it up, and most importantly make it look bad-ass. To do this, I decided to swap out the front assembly and rear wheel to something off a sport bike, so I proceeded to dismantle her, and sold off the parts to help fund the project.
You probably noticed that there’s a different gas tank in the second picture. The original tank had a Kreme-liner-gone-horribly-wrong. I initially tried to salvage it, pulling out a load of dried-up, detached sealant, but some was persistent on clinging to hard-to-reach areas. There was also about chunk that had run to the bottom that was about 1” thick. I had to stab it with a long screwdriver, manage to pull it to the fill cap, chip some away, drop it, and repeat. I tried soaking in Acetone, Methyl Ethyl Ketone, cleaning vinegar… nothing would touch it.
After I got out as much as I could, the inside was completely rusted – but not rusted through. I filled it with cleaning vinegar, threw in some screws and proceeded to shake. And shake. And shake… After dumping out the rusty mess – apart from the small bit of still-clinging tank liner – it actually looked pretty good, but would immediately rust back.
However, I found the black tank for $60 on craigslist. It was great inside, but the exterior is rough.. crappy bondo job and paint job.. but it’s okay for now.
Little-by-little I've acquired most of the big stuff.. Front forks, new rear wheel, carb kits (which were backordered for about 6 months), reg/rect, etc. (Complete parts list at the end).
Originally I was going to use the front assembly and rear wheel from a 2003 Yamaha R6. The front was easy. I got a CB750-to-R6 conversion stem from CognitoMoto and had them press it in to the lower triple, swapped out the bearing races, and put them right on. Using the rear wheel, however, proved to be slightly more difficult than I expected.
The R6 had a 17"x5.5" rear wheel - much bigger than stock. However, I was hopeful that using an offset front sprocket and possibly machining the hub of the wheel, I could bring the chain in line while still clearning the frame. While I could get the chain lined up well, the 180mm tire would rub on the swingarm, and I was recommended to not go with a thinner tire on the 5.5" wheel. On top of that, I was going to have to have a custom axle machined to go from the larger R6 axle diameter to the 20mm stock swingarm slots.
Eventually, I decided to go with a rear wheel from a '95 CBR600 I picked up on CL, which has the same 20mm diameter axle and can fit a 160mm tire, which would solve my allignment/tire rubbing issues. I picked it up for $100, stuck a 160mm Shinko R005 tire on it, stuck it in the swingarm, and everything looked much better!
The CBR wheel doesn't quite fill the entire space between the swingarm, so it needs spacers to keep it in line. I measured, modelled, and 3D printed some mock up ones, which seem to do the trick. I need to have them machined from aluminum, blast and paint the swingarm, replace the swingarm bushings, and weld on a brace for the caliper. After that - the rear end should be close to finished.
In the mean time, I did some work with the electrical system. First I picked up a 7" matte black headlight from Dime City Cycles, but needed spacers to fill the gap between the light and my new speedmotoco headlight brackets. Luckily, my friend is a pretty savvy machinist, so I took some measurements, he turned some out on the lathe.
Now, I'm waiting to get a kit from Vintage Connectors to replace some of the 3.5mm bullet connections, so that I can put in my new Regulator/Rectifier, wire up the headlight, and replace some of the deteriorated square plastic connectors.
It's come a long way, and still a long way to go, but I'm very happy with how it has turned out thus far. Here she is in her current state:
=======================================================
Major parts bought so far:
- Front assembly (forks, wheel, brakes, handlebars) and rear sets from a 2003 Yamaha R6
- Rear wheel from a 1995 CBR600 and new Shinko 005 160mm tire
- Front fork conversion stem, steering head bearings, and 3/8” 530 offset sprocket from CognitoMoto
- Stainless steel engine bolts
- Second Supersport tank
- Speedmotoco headlight brackets
- DCC British Style headlight
- Rick’s Motorsport Regulator/Rectifier
