Swan's Honda CB400F restoration, my fifth one


Kickstart, shift on right, drum brakes and spokes
This is a build thread for a 1975 Honda CB400F Super Sport. This is my 5th CB400F rebuild and I decided to make this one a 100% factory stock restoration that runs and functions perfectly and sell it this spring. I absolutely love building and riding these bikes, but I do not have room in my stable for a third bike. Our shop (the Winona Riders) is full and I am slowly completing and selling my project bikes so I can make room in our workshop and patiently wait for my next future British bike project to come along.

An interesting thing happened when I sold my fourth CB400F Super Sport build last spring. That bike was cafed with British styling (lower bars, black cylinder paint, manx seat, no signals etc) and it took quite a while for the bike to sell. There was a lot of interest from younger poeple but they simply could not afford it. Many of the inquiries I got were people interested in a stock version of the bike, not a cafe racer (even though it was marketed as a Cafe Racer in 1975 and 1976). Older people were trying buy back the bike of their youth or buy the bike they wanted when they were younger but could not afford to back then. A few women wanted a smaller, reliable stock bike. So fighting all desire to modify this one to my tastes, I am leaving this bike 100% bone stock. A really nice low mileage stock CB400F sold recently on Ebay for $8600. The restoration was straightforward and by the book (Honda factory Service and Haynes manuals), and I will include many images so other CB400F owners can use them for reference on their builds.

The Buy:

I found this 1975 CB400F on Craigslist last spring, could not pass it up and drove 7 hours roundtrip to pick it up from a nice guy in southeastern Wisconsin who had a barn full of old Japanese bikes. The price was fair, it was nearly complete (no tank), unmolsested and was titled, so I snapped it up knowing I would not have time to touch it until winter. My empty trailer had a blown tire on the way to pick up the bike, so it made for a 1 hour delay and a $100 replacement tire and rim. Along with the bike, I bought a few spare parts from him which I cleaned up and sold on Ebay to offset the cost of my trailer repair. The bike had 16152 some miles, turned over with even compression across all 4 cylinders. The tank, tool box and lid and air filter lid were missing but everything else was there. I got her back to the shop, completely cleaned the carbs, changed the oil and installed the battery and tank from another CB400F and got her running. She ran very well and I took her out for a short ride until the front brake cylinder froze up (typical bad caliper seal after sitting for years). I pulled the motor, broke her down to the frame and put her into storage. I had a couple days off over X-mas so started the restoration and have been working on it since. It is nearly done with the exception of the graphics on the freshly painted tank. Again, this 100% stock and wanted to rebuild her from the frame and crank up. Here we go:


I cleaned the exterior of the motor with a vacuum, wiped off the dust, dead insects and grease with Simple Green and pulled it out of the frame.

New gasket and seal kits were ordered and I broke it down by the book. Of course the first thing I found was a striped tachometer cable screw. It will be replaced, so I tried soaking it in Kroil and then tapping it with an impact driver, but the phillips head was already stripped. A screw extractor got it out. The rest of the teardown was straightforward, with no drama or surprises. I was happy to find little to no rust on the hardware and none of the other fasteners gave me problems except for two screws on the carb inlets. I photographed, bagged and tagged everything as I made my way down to the crankshaft. Inside, everything was well oiled with no obvious problems. Everything was measured and compared to factory specification and anything out of spec or looked suspect was replaced with new parts.

I spent nearly 12 hours cleaning, preparing, priming, painting and heat treated all the external alloy motor parts. The stator cover had some deep scratches so I filled them with Lab Metal (a high temperature body filler) and shaped, filed and sanded it smooth. All the alloy parts were sprayed with a light coat of Dupli-Color VHT grey engine primer and after it dried, sprayed all with two light coats and a third medium coat of Duplicolor 1615 VHT Aluminum paint . Once dry, I baked it in an oven for 30 minute cycles at 250, 350 450 degrees F. to harden and make fuel resistant the paint. Heat treating makes this paint very durable and resistant to fuel and oil.

The clutch plates and springs were well within factory specification so they were cleaned and re-installed.

To start I pulled the rotor off the left hand side of the crank. For past projects I ordered the service tool to do this, but was sent the wrong size. Instead, I sprayed with the rotor with Kroil, applied heat from a propane torch and used a 2 jaw puller and it came straight off. Before rebuilding I carefully measured the the tolerance of the bearings on the connecting rods as well as the case and crank shell bearings with green Plasticgauge after cranking all the engine bolts down to their specified torque. All the bearings tolerances came within factory tolerance so they were re-used.

Next, I pre-emptively installed a new DID cam chain, even though the old one appeared to be good. The cam chain is a common problem with this model so now is the time to do it. Both cam chain guides showed very little wear and measured well within factory specs so I reused them. I rebuilt the crankshaft, rods and crankcases by the book and seal both halves of the cases with a light and even smear of Yamabond 3 and of course all moving parts were coated with motor assembly lube and all threaded hardware was coated lightly with anti-sieze lubricant.

The cylinder bores were all even and within spec. I checked the piston ring gaps and all 12 rings and 2 were nearly out of spec so I replaced all the rings. First, I brought the cylinder to master motorcycle machinist Skip Green from Apparatus MC just down the street and he checked the bores again and give the cylinder a light and proper honing.

All new seals and gaskets were used on the rebuild. Everything came together nicely with no problems. It is so nice to assemble motor with clean and new parts. The valve stems, guides, springs and seats were all well within spec and reused and replaced in the original cylinder. I did do a light lapping of the valves with fine grit compound to ensure they sat nice and tight. The assembled cylinder head was installed and torqued down in the correct pattern to the correct specs.
The clutch plates and springs were well within factory spec so they were cleaned and re-installed.

Looking good!

Tight work, dig these bikes. These things continue to demand decent money (although rattier ones are still to be found!), but the stock resto has gotta be the way to go for the best resale.
Thanks CC!


I broke the CB400F all the way down to the frame, cleaning and inspecting everything. I was pleasantly suprised to find no damage, alterations, previous repairs etc and that the frame was straight and true. All the black bits were were media blasted, inspected and there were no problems. The freshly blasted bits were powder coated gloss black at Custom Powder Coating in Minnesota City with the exception of the triple trees/ yokes and battery carrier which I spray painted and heat treated with Dupli-Color Low Gloss Black. Custom Powder Coating finished my parts in less than two days for $100 and now I could start to go clockwise on the project. Very little of the original frame and motor hardware was rusty or had damaged heads or threads. I cleaned every single nut, bolt, screw, washer etc in my parts washer and replaced anything which was bad or rusty (top shock nuts, engine cover screws, side and center stand springs etc).

I can lift a CB400f motor by myself but I did not want to risk scratching the freshly powder coated frame, so I turned the motor on its side atop a padded moving blanket, slipped the frame over the motor and bolted it up. Next, I turned it upright and then lowered the frame and motor to a motorcycle lift and installed the rebuilt forks, shocks and wheels. I picked up a Snap On brake spring specialty tool a while back and used to put the center and side stand springs easily and in one try and in a matter of seconds. No more fighting tight springs with a screwdriver!

Forks and shocks.

The forks and shocks needed to be rebuilt and installed so I could determine the offset for my rear wheel. The fork teardown was simple with no problems. I soaked the bottom hex screws of the forks overnight in Kroil and the first one came out easily while the second was more difficult and I need to compress the shock to create sprung tension on the internal components so they would not spin while I loosened the bolt. Inside everything was in very good condition with plenty of fork oil, no rust, pitting or wear. I cleaned all the internal parts and painted and heat treated the fork sliders with Dupli-Color Silver. New fork seals, boots and new top nuts were installed. The springs of the rear shocks were rusty so I soda blasted them and scrubbed them in my parts washer with fine steel wool. They look better and their rebound actions are fair but I may simply buy a new pair because of the remaining rust.


Initially I measured the offsets of both the front rear wheels, cut the original spokes with a bolt cutter and cleaned, polished and/or painted the hub components. The front hub is centered over the rim so the offsets were easy. I reused the original rim because it cleaned up beautifully and Honda DID are no longer selling 18" rims.. New bearings, spokes and nipples were installed and I trued it to less than .005" radial and axial runout. I mounted the trued front rim in the forks and ran straight edge pieces of steel under the frame back to the loosely laced rear rim mounted in the swing arm. The idea is to line up the exact centers of both rims so the bike rolls and tracks smoothly. I have done this with other bikes and they ride extremely well. After several careful measurements I got my rear offset but I wasted a bunch of time, cleaning up the rear rim, lacing it with new spokes and nipples and spent nearly two hours to trying get the rim to roll true. It simple refused to do so and I believe the rim was bent after bumping a curb or some other reason. Honda/ DID quit making 18" replacement rims but with luck and patience I picked up a brand new NOS rear rim from Ebay. It laced up quickly and I was able to get true with the correct offset in less than 30 minutes. Lesson learned, always check your rims before your cut out the hubs to see if it can be trued. One of the few things I outsource is wheel balancing. I brought both rims to Gary Russel Power sports where he installed my new rim strips, tubes and tires and then balanced them on his computerized wheel balancer. $50 later, I was ready to build a rolling chassis.

Wow! Incredible. The attention to detail and arrangement of the photos alone show that you are very meticulous not to mention the quality of your build. Nicely done. Great to see another bike that will live again.
Really enjoying your thread! I really like your detail about the individual steps and the simple, effective approach you are taking. You've already inspired me to paint my own fork sliders rather than having them powdercoated for $100, a cost inhibitive price for me. Did you do the same technique for your rear brake drum housing as well?
Thanks, rear hub and cover were painted with Dupli-Color Aluminum and heat treated too.
Yay, another nice restoration from you - I'm on board for this one.
Looking awesome, and perfect timing to use your resto as an inspiration for my now parts bike, thanks for sharing!
+1 On Dingo's post, true inspiration to "doin it proper" 8) ime hooked :p
Thank you all very much. Restorations are more work than most people realize. Here is another round of updates with loads of images. I am nearly done with the tank and plan to start her this week, synch the carbs and shake her down.

The original seat was in good condition but had a small rip in the cover and was quite dull in color. The seat pan was a little rough so I welded and filled some bad areas and fabricated several new metal hooks to grab and hold the seat cover. The foam was in remarkably good condition so I reused it and topped it with a new replacement set cover with new chrome split pins and belt hardware. This is the expensive kit from Sirus in Canada ($95.00) with the correct silk screen Honda logo, seat pattern and hardware. I have used this kit before and was happy with it, but this time the split pins were very difficult to bend, the metal was thicker than previous split pins. The seat now looks better than new.

Fenders and tail light
I cleaned and polished the fenders, stays and taillight. The exteriors cleaned up very well with Simichrome but the undersides of the fenders and taillight were rusty (as usual). Rather than buy replacement fenders, I walnut shell blasted, primed and painted the undersides of the fenders silver to stop the rust. If the new owner wants to buy replacements fenders, this is an easy swap which can be done in a few minutes with basic tools. For now, this makes them look much better, easier to clean and prevents rust.

The freshly blasted and painted battery carrier/air filter box was installed along with a new battery. I inspected, tested and cleaned the wiring harness and replaced one connector missing for the ground wire for the right rear turn signal. Again, it is so refreshing to work with an unmolested bike. I tested the right and left hand controls and determined the left hand control was bad and beyond repair. I picked up another off ebay for $20 despite the fact Honda no longer offers this part. I have seen ones in much better condition go for $150 and up. I cleaned the switch of the new left hand control, tested everything and all was good but it is a bit longer since it is for a 1977 model with higher bars than the 75 and 76 models. . The original ignition switch went bad soon after I brought the bike home (age-bad plastic) so a new switch was installed. The head light was installed and I tested and replaced some of the idiot lights on the control panel. I have restored more than a dozen vintage bikes but this is only the second bike I have worked on with turn signals. A previous CB400F with turn signals was plug and play but this one gave me grief. I swapped the blinker relay with every other relay in the shop and still could not get them to work. Triple checked for correct bulbs and added a ground wire to the front bulb sockets and still could not get them to work. Re-tested the switch and it was fine. Had to walk away. While out running errands I decided to pick up a universal 12 volt relay from an auto store and sure enough, it made the turn signals work beautifully. A simple $7 solution.

As usual, my original gauge faces were sun faded, dull and dirty but both were in good working order with 16,154 miles on them. I ordered a vinyl dial face kit from Ebay, cracked open the clocks, cleaned and polished the lenses, painted the housings, replaced the bulbs, painted the orange needle tips and applied new dial faces. There are two methods to do this and I opted to cut the crimped bezel, redo the faces and then JB weld the bezel back in place. They look so much better, before and after:

Chain and sprockets
The original chain was crusty and rusty so I decided to replace the chain along with new sprockets front and rear so everything breaks in and wears evenly. Both sprockets are stock teeth count (17 front, 38 rear) and I also bought a new chrome chain guard from David Silver Spares USA.

I have done several Honda front disc brake restorations before and decided to completely redo this system to get enough reliable stopping power. First, I removed the frozen piston and pad by screwing in a grease zerk and pumping the brake cylinder full of grease. This technique works beautifully. After cleaning the housing inside and out I painted and heat treated it with Duplicolor VHT low gloss black paint to match the original paint. I cleaned and rebuilt the master cylinder with a new piston and o-ring, brake pads, bleeder and upper and lower hoses. This set up with new modern brake pad materials stops the bike much better then when it left the factory. New shoes for the rear drum too.

To my eye and ear, the original 4 into 1 exhaust header absolutely makes this bike such a beauty and and thrill to ride. The original headers were dirty with some slight rust spots, but no major dents, scrapes or repairs. The original muffler was in bad condition, cracked and heavily rusted inside and out. I cleaned up the header and it looks good, but I decided to bite the bullet and ordered a new 4 into 1 and muffler from David Silver Spares ($466.00). To me it is worth the expense because the beautiful, swoopy and sexy design of the header makes the look of this bike. Previous replicas by other vendors were very angular, lacking the sexy curves of DSS's versions which are nearly identical to OEM. I did watch a New Old Stock OEM headers sell for something like $1700 recently on Ebay, insanity. I sold the old set on Ebay to offset some of the cost of the new set and soda blasted the collars to remove the light superficial rust.


I had cleaned the carbs from this bike while working on another CB400F last summer. It takes about an hour completely clean and polish each carb. I do them one at at time, methodically and clean and check everything. These had been on the shelf for a few months so I re-cleaned them and re-checked the float levels, all good. I am running the stock air filtration and ordered a new air filter and new filter box lid. The rubber carb inlet boots and rubber connection to the air manifold were rock hard as usual so I soaked all for 12 hours in my home brew Rubber Renew (methyl salicate and xylene) and now they are soft as new and made installation much easier. (see http://www.dotheton.com/forum/index.php?topic=2692.0)I installed two new carb cables, new filter and air box lid. It is very important to use OEM Honda carbs parts and not after market replacements like K&L, etc. I spent many, many hours struggling with with this on my last CB400F build only to aliviate the problem with OEM parts. A good reference for carb rebuilding is an article by Tim Boughen http://www.docstoc.com/docs/97200467/CARB-REBUILD-101

Whew, that's it for now. Hope to have her on the road this week to shake her down and then sell her. Stay tuned...
Nice stuff Swan. I just ran across this build. You're getting pretty quick at getting them out the door. When do you want to stop by and pick up your next Brit project? :)

edhaeuser said:
Nice stuff Swan. I just ran across this build. You're getting pretty quick at getting them out the door. When do you want to stop by and pick up your next Brit project? :)

After I sell this one.
Thanks all! A quick update. I have put 30 shakedown miles on her and so far so good with only a few problems. Firstly the tank still had tiny bits of rust and crud that slipped past the filter of the new petcock screens and my inline fuel filter and causing one of the crabs to piss gas, or so I thought. I flushed the tank again, added a new filter and finally cleaned the inside of the tank with an electrolytic setup. This removed the last of the remaining rust but uncovered two tiny pinhole leaks on the underside seam which i filled. I cleaned the carbs again but one was still pissing gas so I knew the float valves and seats were worn, so new ones were installed and the problem stopped.

The bike starts right up, idles very well and rides extremely smooth. I am gently putting on some miles to break in the new rings and I forget how fun and easy handling these 400's are. The new DSS exhaust system sounds fantastic. I will change the oil and filter at 50 miles, tightening and recheck everything and then do another 50 miles or so and consider her done and ready to sell.

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