Author Topic: Another Honda CB400F cafe racer  (Read 64228 times)

Offline swan

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  • Kickstart, shift on right, drum brakes and spokes
    • 1962 BSA Gold Star barn find restoration
Another Honda CB400F cafe racer
« on: Aug 05, 2012, 16:54:01 »
This is a bike build thread for a 1975 Honda CB400F Super Sport café racer with a series of catch-up images and an overview of the work I have done to date. This is my fourth CB400F crank up rebuild so I know this bike well but unfortunately I cannot keep this one for I need to sell it to finish my (overly documented) BSA Gold Star project. I am however building it as if I were keeping it and to my normal build standards. There are several bad cell phone images, so forgive some of the poor images.

It will be rebuilt with slight cosmetic and mechanical modifications and the goal is to have it look like a came from the factory with British stylings (black cylinder, Honda front drum brake, custom Manx single seat, Lucas tail light, clubman bars, Dunstall replica exhaust etc). I deliberately did not hack up the frame or make any modifications so it could be converted to stock should the new owner wish to do so. It will be very similar to two other CB400f’s I built and sold:

Honda CB400f’s were produced from 1975 to 1977 only as sleek, light and fast factory designed café racers. Café racer styled motorcycles did not sell very well in America in their day so in 1977 the handle bars were changed to be more upright and the foot controls more forward to appeal to American tastes. Only 5060 1977 CB400f’s were imported to North America. The CB400F has a cult following in Europe, Japan, Africa and America and most every part is available in NOS and/or aftermarket reproductions with a few notable exceptions.  Also, Honda parts are much less expensive than the British parts I have been buying lately.

The Honda CB400F is a marvel: It handles remarkably well, stops with authority, snaps through the gears precisely--and motors along smartly. The bike feels all of a piece, as if a hundred separate design systems fell into perfect synchronization. Yet the attraction of the 408 transcends its obvious competence. Even a card-carrying Anglophile would agree that the CB400F has real character. If you can't respond to the CB400F's electrifying mechanical presence, you should immediately switch your sport to checkers."--Cycle World, March 1975.

My bike is a low, low number (one of the first 750 ever built) and low mileage 1975 CB400f bought for cheap as a untitled basket case, missing the seat, tank, side covers, brake pedal but basically a roller (sorry, no dramatic “before” image). I titled and registered the bike and then stripped, cleaned, prepped, primed and painted the frame and put it in storage while I worked on my BSA Gold Star.  During that time picked up a tank, side covers, brake pedal and a few other missing bits along with new bearings, seals and gaskets, hardware, tires and more. My friends and I now have a proper workspace (the Winona Riders workshop) and a lift table so I am now finally building this bike. I hate to sell it, but I have a Gold Star to finish and ride so here we go:

Frame and Forks:

The frame, triple trees, stands and other black bits were cleaned, inspected, prepped and painted with a two-part catalyzed gloss black automotive paint. The swing arm was installed with original bushings (still good). I cleaned up the rear shocks and installed them.

The original fork tubes are in fantastic shape with no wear or rust anywhere. They are the best I have ever seen on an old Honda.  I meticulously cleaned everything and sanded, polished and buffed the sliders. New OEM bottom bolts, copper washers, dust caps and forks seals were installed. They were filled with fresh fork oil and work perfectly.

Although not for everyone, I used a Honda CL/CB 360 front drum brake on this bike. Many people are quick to hate drum brakes yet have not made the time to learn how to set them up, adjust and maintain them correctly. To my eyes they not only look better on a café racer than disc brakes, they do in fact work very well. I simply hate dealing with brake fluid (its feel, smell as well as its paint removing abilities) though I have rebuilt more Honda master cylinders than I can remember. I am also rebuilding the original front wheel and disc brake system with a great rim and new spokes as an option for the future buyer.
The front drum was in good shape so I dissembled everything for cleaning and polishing. The rim was in poor condition so I bought a correct used 18”rim in very good condition, (Honda no longer sells 18” DID rims in the US, grrrrr) The old factory finished of the plate and hub was removed with aircraft paint stripper, wet sanded with 400 to 1500 grit sand papers and polished and buffed with black, brown, red and white compounds. I laced and trued the rims with new spokes and nipples, pressed in new bearings and added new tube, rim strip and a new 100/90/18 Dunlop D404’ tire. I had a local shop dynamically balance both wheels on their computer. I got the front wheel perfect but the rear needed a few weights.

stripping factory finish

Beautiful and functional.

The rear hub was an absolute nightmare and took a lot of time and energy and I considered buying another used one, but in the end I tackled it. Good thing I like a challenge. It was covered in rock hard grease, oxidation and the brake shoes were frozen to the drum and the sprocket was not coming off until the BFH (big fuckin’ hammer) appeared.

The OEM chain cover over the sprocket was removed by drilling out the rivets and though I repainted it, decided not to use it.  After degreasing, scrubbing and media blasting, I painted the hub and cover with VHT silver paint and heat cured the parts in my oven. New bearings were pressed in, the rim polished, new spokes and nipples laced and trued the rims to .005” lateral and radial tolerence. The hardware was zinc plated, new brake shoes and springs and a new sprocket was installed. Both hubs were spun on the stand and I used varying degrees of sandpaper to remove the crud, rust and bring inner drum lining closer to truth.

Media blasted

Ahhhh, much better

To determine the correct offset of the rear hub I centered the front rim between the forks, laced and trued it. Next I ran parallel straight edges from the trued front rim to the loosely laced rear rim to determine the correct position relative and in line to the front. then I measured the offset on both sides and then trued the rim in my stand. The centers of both rims are perfectly aligned.

Centered front rim
front to..

...to determine alignment and rear rim offset

with the correct offset the rear rim was trued on the stand

I mounted new Dunlop D404's (100/90/18 front and 110/90/18 rear), tubes and rim strips and got to one of the best moments of any build; ROLLING CHASSIS!

Motor rebuild coming next…
« Last Edit: Aug 05, 2012, 17:03:51 by swan »
1966 Triton cafe, 1962 BSA Gold Star DBD34, and 1966 T120 Triumph Bonneville.
BSA Gold Star barn find restoration
1975 CB400F Cafe Racer build
1966 Triumph Bonnevile restoration

Offline swan

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  • Kickstart, shift on right, drum brakes and spokes
    • 1962 BSA Gold Star barn find restoration
Re: Another Honda CB400F cafe racer
« Reply #1 on: Aug 05, 2012, 17:33:13 »
Motor Rebuild

Here is a quick overview of the motor rebuild. Nothing fancy or tricky, but I took my time to do it right following the factory service manual and a Haynes manual. Cleanliness was important as well as measuring everything, taking notes and using plenty of engine assembly lube. Any part that questionable or bad was replaced. The engine cases were cleaned, degreased, prepared, painted and heat-treated with Dupli-Color VHT aluminum 1615 paint. Three sessions of oven curing 150, 200 and 300 degrees F hardens the paint and make it oil and gas resistant.

Next was a meticulous crank up rebuild, ensuring all components are to factory specifications. Anything that was out of spec or questionable was replaced with Honda OEM parts. All new seals and gaskets were used. The rotor is difficult to remove without the proper Honda service tools (which I purchased but was given the wrong size). I opted to borrow a heavy puller from an O’Reilly’s auto store to remove it (along with PB blast and heat it came off easily) New seals were installed on each end of the crankshaft.

All the crankshaft journals were measured, the bearings checked with Plasticgauge and fortunately everything was well within factory specification confirming this is a low mileage Midwest bike that saw little abuse or use. The cam chain guides show little to no wear and everything inside the motor looked great, no drama, all good.

The cylinder, pistons and rings were cleaned and checked, all good.

New main shaft bearings and snap rings were installed, the transmission, cam chain guides were inspected and then I buttoned up the lower end sealing each half with Yamabond. All good.

The cylinder was soda blasted and painted (non-stock) gloss black with VHT paint and heat cured in three cycles.

The cylinder head looked awful and took several hours to degrease, dissemble, clean, soda blast, prepare and painted high temp black and heat cured. One valve head was corroded so I replaced it with another I had in storage. All the valve stems, springs and goods were to factory specification so the were cleaned and the valves ground in and installed.


The motor was placed in the frame by myself (easy and lighter than a CB750 motor) I have done many time before and use pipe insulators to protect the frame.)

The oil pump was dissembled, inspected and cleaned. All good. put in the starter, new sprocket and chain and installed the left hand cover. All the threaded holes on the engine cases were chased with a greased tap and I used a stainless steel allen bolt kit for all the covers with anti-sieze lubricant on the threads.

The gear change assembly was cleaned and installed. Clutch was in good shape and plates and springs have plenty of life left in them so they were cleaned and installed. I made a service tool to torque the clutch hub nut. An old socket cut to fit the four slots on the nut, not pretty but effective. I polished the clutch inspection cover and roughed in the clutch cable so it functions, but I will shorten the cable later this week.

New chain and sprockets were also installed as set. I did drop the front sprocket to a 16 tooth based on research and others’ recommendations. The 6-speed transmaission has a short first gear so this may help a bit.

The OEM 4 into 1 exhaust was in good shape, not perfect, but good.  This piece of plumbing with its sexy, swoopy and curvy bends is one of the most beautiful headers ever. New Old Stock (NOS) ones are selling for $1200 and up on Ebay. I see David Silver Spares in the UK are selling very nice reproductions but I am sticking with this one and after cleaning and polishing it it looks pretty good.  Also I soda blasted the exhaust collars and they look great. I bought a replica Dunstall muffler and with some extra baffling. The Emgo Dunstalls work and sound better when you replace the tissue paper thick fiberglass that comes with them with better baffling. I run two Dunstalls on my Triton with the same set up.

original baffling

Moose baffling

I was inspired by this video:

I spent a lot of time, money and energy tracking down and buying a lot of the little bits that were missing as well re-zincing most of the hardware. The motor, exhaust, rearsets, brake pedal, kickstarter etc were finished and installed last night and I set the valve tappet clearances so I can now add oil, do compression and leak down tests and then start work on the carbs, electrical, tins and seat. Stay tuned…

« Last Edit: May 13, 2013, 15:01:47 by swan »
1966 Triton cafe, 1962 BSA Gold Star DBD34, and 1966 T120 Triumph Bonneville.
BSA Gold Star barn find restoration
1975 CB400F Cafe Racer build
1966 Triumph Bonnevile restoration

Offline NeightRG

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Re: Another Honda CB400F cafe racer
« Reply #2 on: Aug 05, 2012, 17:54:19 »
I'll be watching this build very closely... Closer than most. Looking good.

Offline andycafe

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  • Northern Suburbs, Melbourne Victoria, Australia
Re: Another Honda CB400F cafe racer
« Reply #3 on: Aug 05, 2012, 20:15:11 »
gee you have been a busy boy  ;) lucky new owner to have you rebuil this, good job.....

Offline BigRedButton

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Re: Another Honda CB400F cafe racer
« Reply #4 on: Aug 05, 2012, 20:17:00 »
Again, epic.
Common sense turns the wrench.

Offline Big Rich

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  • Heaven is so far away.
Re: Another Honda CB400F cafe racer
« Reply #5 on: Aug 05, 2012, 21:04:52 »
Yup......signed up for sure.

Great work Swan - the future owner should be very happy with a "new" 400F.

Offline Worst cb650 ever

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  • You can always get it running with time or money.
Re: Another Honda CB400F cafe racer
« Reply #6 on: Aug 05, 2012, 22:51:39 »
I'm onboard - it looks awesome!
DTT Blue (cause Winter is Coming) CB360 Club.

1995 CBR900RR - a winter flip not worth a DTT writeup - Sold

1986 Yamaha SRX600 - mailed to me from California - build coming soon?

1983 VF750F

1976 CB360T

1993 CBR900RR - Sold

1979 CB650 - Sold

Offline VonYinzer

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Re: Another Honda CB400F cafe racer
« Reply #7 on: Aug 06, 2012, 00:48:14 »
Like a river that don't know where it's flowin'
I took a wrong turn and just kept goin'

Offline Kwality

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Re: Another Honda CB400F cafe racer
« Reply #8 on: Aug 06, 2012, 03:01:43 »
Your work and documentation are top-notch.  Count me in!

Offline wilber551

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  • dirt/street
Re: Another Honda CB400F cafe racer
« Reply #9 on: Aug 06, 2012, 03:31:49 »
Your work is very respectable. I'm also building a 1977 400F. Ill be watching

1977 CB466
1984 XR100 Brat
2012 KX450F
2012 KX250F