1981 Honda CB750K Build Plan (Updated 7/7/20)

Scroll to the bottom for the build plan.  

Barn Bike: 1981 Honda CB750K

I found a great deal on a barn find 1981 CB750K.  It was completely stock, some pieces damaged but nothing was missing; most importantly, the tank wasn't dented.  Surprisingly, the bike started right up with some starter fluid and the choke open; this was a great sign.  Wes, like the trusty motorcycle friend he is, set off with me to snatch this bike up.  The old guy letting it go was amazing.  He wanted to restore it but just didn't have the time or energy to put into, luckily I do.  Along with the bike he gave me tank restoration chemicals, a complete engine rebuild manual and all the parts he bought for it.  For craigslist deals it was pretty ideal. 

Once I got it home I quickly stripped the fenders, turn signals and side covers to get a quick glimpse of a cafeish CB750.  I had always wanted to see my other bike like this but never wanted to strip it knowing id have to put it back.  I started taking things off one by one intending to leave it in bite sized chunks so as to not overwhelm myself; but then I realized: I have a perfect reference sitting three feet away.  For everything I forget about disassembly can be quickly reminded by the fully assembled bike sitting next to it.  Because of this, I committed to a full bike strip down.  I now have a wealth of spare parts for my other bike, some of which I will sell, especially the flawless seat.

Cafe Racers are the perfect mixture of things i'm into: designing, building, racing (watching), motorcycles, etc.  I really didn't know the first thing about how to design and build a motorcycle, but being completely ignorant to a subject has never kept me from jumping fully in before...  After getting the motorcycle in front of me I finally started to get a real feel for the amount of work that would go into transforming this bike into a true cafe racer; it was a lot more than just taking some fenders off.  Cafe Racers are designed for aerodynamics and efficiency; which means low to the ground and stripped of everything that isn't necessary to racing to get every ounce off the bike.  Now if I actually wanted to drive this bike farther than my neighborhood, there is some trickery that needs to go into the design.  You have to include everything that would keep this bike street legal while hiding as much as you can; mainly being the turn signal controls, battery, minimizing speedometer, fuses, etc.  The work list for completing this build was quickly becoming large.  Because of the bike theme I had chosen, it meant finding and making use of as many appropriate genuine Honda parts as possible.  

1981 Honda CB750K Cafe Racer Build Plan:

Rear Sets - brackets sourced from the "Sports Kit" on the German version of this bike.  Sports kits have disc rear brakes, need to make these work for drum brakes.  Need new swing arm and engine hanger bolts.  Also need to remove the current brackets that are welded on the frame.  

Dual front brakes - forks and brakes sourced from a CB750F

Lowered front suspension - forks must be non-air assisted or you cannot shorten them for the right look.   I didn't want the forks sticking up out of the triple tree much.  These are typically 79' or 80'.

Seat and Cowl - must look like a Honda design, following the contours of the tank. Need to cut off the rear of the frame and weld on a cafe loop.  Would like an integrated rear light in the cowl, not in the hoop like most cafe builds.  Hawk seal and cowl from Hookie Co.  

POD Filters - to eliminate the airbox and run pods, the carbs must be rejetted.  

Engine Rebuild and Paint - Randakks Cycle Shakk sells complete rebuild kits.  Paint the engine gloss black and polish the fins.

Wheels - I like the large rims from the wheels on the CB750K(Z), the European/Australian version of this bike.  Running a larger tire would close up the "fender" gap.

Controls - Clip on handlebars are the standard look for cafe builds to bring the sight line down to the tank.  Replace hand controls with Motogadget buttons and turn signals.  Use Motogadget M-Unit to completely rewire the bike.  Motoscope Tiny as the only gauge.  

Electronics and Battery Relocation - relocate to clean up the triangle.  Lithium ion battery and a Rick's reg/rec.  Battery will go under the swing arm and the electronics will be tucked up under the seat.  

4into1 Exhaust  - Black MAC headers and Spark Performance muffler.  Wrap in white exhaust tape.

Stripped and Semi-Polish Tank - dropped it off at a tank restoration place to remove the rust, line the inside and strip the paint.  Need to grind off the side cover brackets.  Will clear coat the raw steel tank and clean the stock badges.  

Frame Modification and Paint - Remove the current peg wings, side cover brackets and bike stand.  Remove the tail of the bike and weld on a cafe hoop.  Clean and repaint satin black.