Rat City Bikes Blog

1980 CB750 Custom transformation into a sweet cafe racer.

  A little history. In Summer 2013 I bought a 1980 CB750 Custom for $1150 from Blaine Lake Sk. The family was moving to the U.S. and was unable to take any of their motorcycles. This bike was in such nice condition with only 17000km that I knew what I must do... Tear it apart limb from limb and build the sickest fucking cafe racer this side of the Rockies!

 

  

  First things first. Remove all the cosmetic shit. Tank, side covers, fenders, seat etc. Next to come off are the wheels and that heavy 4 into 4 exhaust. 

  The next thing I wanted to do was to cut off the whole rear section of the frame.  I really like the older CB750 style where the tank and seat are in a nice horizontal line.

So I just started cutting. I wanted to put a hoop section on the rear with a slight kick upwards. Unfortunately that meant cutting out and re-positioning the shock mounts (a pretty ugly job). Also I de-tabbed the frame at this point.

 

  

  I fabricated a rear hoop section and welded it on. If possible, use a slug inside the frame tube for strength. Then I fabbed some new shock support gussets from 3/16" steel and put the whole thing together.

I removed the battery box and moved all the electrical shit from behind the airbox to clean up the look a bit.

  I bought a Ballistic EVO2 battery which is nearly 10 lbs lighter than the standard type and is super tiny as well. I got the 8-cell one which is good for bikes upto 1000cc. These are not cheap (about $200) but are small, light, and very durable and can be mounted in any position because they are a "dry cell".  I fabbed a battery box to be hidden under the seat. I welded some little tabs to it and mounted my rear signals to them (above)

 

                                         Battery box (left) and painted with battery installed (right)

 

  If you are looking for these Ballistic batteries, they are red. I just painted mine to camouflage it under the seat.

 

  You can see in both pics that I made some mounting brackets to hide some of the electrical components up near the tank mount.

 

  Somewhere during this phase I replaced the stock coils with coils off a 1996 CBR900. I did this on another bike and noticed a huge difference! I guess the 1980 coils are not as good as the newer ones.

 

  I had the tires removed and sent the Comstars out for blasting and had them powder coated a semi-gloss black. Since powder coating requires the part to be baked for a few hours at 400 degrees, I removed all bearings and seals. I figure that if you have all that shit out it only makes sense to replace with new, instead of putting old parts back in and then possibly having to deal with it down the road somewhere... Literally! Just a quick note, Always double check that your rear wheel spacers are on the right sides Haha or you will wonder why the wheel isn't centered.

  I am really happy how they turned out and they will be durable and looking hot for years to come.

Then I hacked the seat apart and kept only the front part which mounts to the frame. I welded another piece to it and shaped it to the contour of the frame. Stay tuned for more on the seat, I need to get the tank first and tie it all together. Looking at making a removable cafe seat cowl but more on that later.

  This is also a good time to have a look at the brakes and make sure nothing else needs attention. After some dicking around to find a rear sprocket, I finally got one from JT Cycles and when it showed up I was able to install my wheels with new chain and sprockets. Stock for this bike is an 18 front and 43 rear but I wanted to gear it like my CB750k so went with the 18-46 combination.

 

  Finding a tank for this build proved a bit more frustrating. I've learned that if you live in Canada you cannot purchase a tank from the U.S. on ebay. I tried twice and was denied twice. I almost decided to go with the stock tank which has a cruiser/ teardrop shape to it (fucking ugly) when I found this red beauty out of Quebec. Very nice condition, off a 1977 CB750 and very clean and rust-free on the inside which is key. Unfortunately when I tried to fit it, it was hitting on the frame rails so I did what any respectable bike builder would do... I beat the shit out of the underside of the tank with a fucking hammer! Voila! fits perfect now. Bent down the rubber bumpers to touch the frame and fabbed a new mounting bracket and it's good to go. 

 

  "You can always get the job done with the right amount of brute force and ignorance"

                                                                                                      - Blackie-

 

Hammer Bashing is Fun!

  This tank is in such nice shape that I'm not even going to paint it. I never thought I would have a red bike but I will try it and can always paint it later.

  Obviously I scrapped the whole gauge cluster 'cause it was big and clunky. I decided to go with a mini speedo and no tach. For the indicator lights, I fabbed a bezel to bolt on the old handlebar mounting holes (because I am using clip-on handlebars) which will also hold the choke. Here's a couple shots of how I made this piece.

Finished (except for paint).

  Now I will wire all my LED indicators for Signals, Hi-Beams, Oil Light, and Neutral. All the wiring will be hidden and will run down the head tube to keep everything clean looking.              -Check back for the coolest choke knob ever!-

  So, I was fucking around with my clip on bars today and encountered a problem that many, if not all cafe builders have... bars hitting the tank! I've heard a lot about this topic and have come up with my own brilliant solution. Fucking genius!

  I took a drill bit and a 12-24 tap and drilled a hole and tapped into the little tabs that stop the steering from turning too far... Then I put a 12-24 machine screw in each tab (with a nut for adjustment if needed). This allows you to adjust the steering limits and stop the handlebars or controls from chipping or denting your nice paint job! The only downside would be that in a tight spot trying to turn your bike around, it won't turn as far. But for the sake of riding comfort, and paint protection, it's a no brainer....You're welcome. (See below)

  Picked up a set of Ottimoto ZX-6R rearsets and once again started removing pieces of the frame. Had to relocate brake light switch, tensioner spring location, and brake pedal stopper. Whew! It's a lot of trial and error (mostly error I'm finding) but I don't mind a challenge. First I cut off the rear footpeg brackets and the fun began.

 

Not quite finished this but it will be interesting to fuck around with the linkages.

  Okay, finally finished rearsets...Still need to paint some parts but it works. Overall, I'm pretty pleased but it was a LOT of dicking around!

  I also got the choke knob done and i said it was gonna be cool... Yeah, it's a speed knob from a Gibson guitar!

  Hopefully a new starter solenoid relay will fix the not turning over issue. It was turning over intermittently and finally just quit. When I shorted the 2 contacts on the solenoid with a screwdriver, it turned over, so I am thinking it's the solenoid...

I also started the rear cowl this week. I rolled some 14 ga plate and fabbed it into shape. Still needs finishing and paint etc. It will look better in a while but fabrication aint all pretty and shit!

Seat Cowl Fabrication 

Wiring is next... Fuck!

Wiring, will it be my demise? Some days I think yes. Today I wired the turn signals and they were turning on but not flashing... My first thought was that I fucked something up, but when I touched the wires with a test light it would begin to flash! WTF? After hours of pulling my fucking hair out, I put a load resistor between pos. and neg. wires and now it works great. Don't ask me why but it does. Most of the other wiring went pretty painlessly, thank Christ. Today it seems that I have won the battle.

Continued with the cowl. I'm fabbing in a stash box for a place to put my insurance papers and other small shit. I'm making so the small "butt pad" on the cowl will be removable with a secret compartment in behind it. I used some of the rubber grommets that used to hold the side covers on and made my own little prongs to fit in snugly. Coming along pretty good, just needs upholstery and paint. Check it out.

 

  Well, I did the paint myself and I guess it turned out okay. The upholstery is finished and it looks great! I rebuilt the carbs and re-jetted from a 108 secondary main to a 112.5 and it seems to run a little funny under load so I will spend the next few weeks re & re-ing the fucking carbs trying to get it right. Also playing with different exhaust baffle options looking for that "Just Right" sound. I also figured out a way to shorten my throttle cables so I don't have a foot of cables sticking out front... 

 

  Here's a couple pics of the finished product.

1980 Honda CB750 Custom Cafe Racer

1980 Honda CB750 Custom Cafe Racer

1980 Honda CB750 Custom Cafe Racer

1980 Honda CB750 Custom Cafe Racer

1980 Honda CB750 Custom Cafe Racer

  Whew! 4 months of swearing, bloody knuckles, frustration, and satisfaction have resulted in what I consider to be one of the coolest, bad-assest cafe bikes around. Any amount of blood, sweat, and beers is more than worth it to have a finished product that I can be this proud of, and I must thank my wife for not getting too upset with my obsession.

 

 Of course a project is never completely finished but this may be as close as I will get. Still a few bugs to iron out but overall I'm pretty stoked about the project as a whole.

 

  So leave me a comment or any questions you have below. Or you can hear the beast run on my Youtube Video:  

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