Another Honda CB400F cafe racer

Awesome work, wanna rebuild my set of carbs too?lol.....
definitely staying tuned for your seat.... :D
I have got to get off my butt and start to work on my projects. Looks great sir. Can't wait to see the finished product.
andycafe said:
Awesome work, wanna rebuild my set of carbs too?lol.....
definitely staying tuned for your seat.... :D
I will if you buy the beer....

Alright, seat update: I brushed three layers of black gel coat into the waxed and PVA release film coated mold-

After it dried, I added a layer of fiberglass and epoxy resin. I use West Systems 105 epoxy and 205 hardener because I am experienced with it.

And then a layer of some thick woven carbon fiber-

After it dried I popped he seat out of the mold and trimmed the flanges. Looks good with a few minor defects that I will touch up. It is very lightweight and strong.

I plan to do the touch ups, the final cutting and sanding of the edges tonight along with adding rubber spacers and a hinge and then on to foam and sewing a vinyl cover. Also my new K&N filters arrived so they will go on too. Stay tuned....
Another update, she LIVES!!! Fired her up, timed the ignition and she is running well. Sounds great with the Dunstall muffler. Carb #2 is a bit intermittent and I have determined it is not the coil or the plug so I need to examine and clean carb #2 again and plan to do so tonight.


I shortened the throttle and brake cables to fit the clubman bars. I use a ferrule or wire stop as the new end. After carefully measuring the existing exposed part of the cable, I measure and cut the sheathing to the length I want. I cut the cable and sheathing with a cutting wheel on a Dremel, clean with carb cleaner, slide ferrule to postion, tighten the screw, flux, solder and then cut and sand it to shape. This method works great.





I had done much of the prep work on the tank prior to storing it. There were a few small dings which I filled with body filler, sanded and primered. I did some tiny spot filing, seal and sanding guide coats, sanded again and then a final coat of grey primer.


I found Plastic-Cote Honda Milano Red is very, very close to the original OEM CB400F Honda red.


Original OEM Honda red.

I sprayed several light, even coats of the Milano Red followed by three medium coats of catalyzed auto clear coat. I will let this sit and off-gas for a couple of days, wet sand, add the decal and spray more coats of clear. Then more fine sanding and buffing with several grades of compounds and glazes until done.

I will clean the inside of tank one more time before adding fuel. If you are going to do it, do it right- new OEM petcock and fuel cap for the freshly painted tank.

Still need to paint the side covers, and headlight bucket, finish mounting and upholstering the seat, paint the undersides of the fenders and few other minor things and soon she will be ready to take out and shake down. Stay tuned...
crqcycles said:
Show us more pics please!
Here ya' go... Quick update:

Tank and side covers are clear coated with graphics. They will be sanded, polished and waxed, but look good already.

The seat was a challenge to line up correct with the stock locking mechanism. I made hinges and cut and pop riveted strips of aluminum as 'teeth" to hold the vinyl seat cover in place once it is stretch over the sides of the seat. Tonight I should be able to sew a seat cover and mount the seat. Stay tuned.

Sorry all, I have been busy with work and other projects. I did however finish polishing the tank last night. Looks good, and plan to install the cap, fuel line and petcock tonight.

I use a heavy duty DeWalt variable speed buffer, several different 3M brand cutting, polishing and final glaze compounds on small wool and foam pads to polish clear coat.

I have been struggling with getting power to the headlight and taillight. I t is not a grounding issue and after many frustrating hours with a multi-meter now believe I may have the wrong left hand control switch. Gonna work on it some more tonight. Once that is sorted It is time time to install the front fender and start riding and shaking her down.
She is alive! Took her out last night for the first of many shakedown rides. So far so good, a couple loose bolts but no other problems. Wow, the repacked Dunstall replica sounds amazing! Runs, shifts, stops well and revs without hesitation all through the throttle range. Need to weld a crack on the front fender mount and install the fender and start doing plug chops and carb synching. I will try to post a video with her lovely exhaust sound soon. Fun!
Thanks all! Still shaking her down. Sounds great but needs some carb work and synching. Hopefully I can make the time tomorrow.
Thanks all! Spent all yesterday fettling, carb tuning and tweeking, test riding and dialing her in. Still needs a tiny bit of carb work but she accelerates, handles and turns like a dream. The repacked Dunstall replica sounds amazing! Electric and kick starts with ease, clutch is perfect, tranny is smooth and easy to shift, suspension is responsive and comfortable and she is a blast to ride. Here are few quick pics after my ride tonight and I have humbly accepted a nomination for Bike of the Month for this beast.






I am having a challenging time getting my bike to idle correctly with individual K&N pod filters. There are dozens and dozens of threads online (Do the Ton, SOHC, Yahoo Auto Groups, et al) discussing this very problem and most say it cannot be done. It can be done and I have successfully run pods on three other CB400f's using stock exhaust, dropping the needle clip one notch and running 80 or 85 main jets. This bike has a repacked Dunstall replica muffler (which sounds awesome!), stock 4 into 1 header, 80 main jets, raised the needle one notch (lowered the clip, enriching the mixture to compensate for more incoming air) and a #38 pilot jet. I have quadruple checked timing, ignition, valve clearances and confirmed there are no vacuum leaks. The carbs, floats levels all passageways etc have been meticulously cleaned several times and set to spec. I am at 700 feet elevation and it is generally in the 50's farenheit when I am doing test runs and plug chops. The bike runs extremely well above the idle circuit, but down low it idles high, hangs, then drops down to a too slow of an idle. This has nothing to do with mechanics of the carbs (slides, springs, throttle cables etc) I believe one or more of the pilot jets are fouling, causing the idle to drop. This has made synchronizing the carbs at idle difficult.

Well, last night I did a series of compression tests with the engine cold, wide open throttle (WOT), cold with a bit of oil squirted into the cylinders and WOT and after I ran the bike around for awhile. Cylinders 1,2,3 were consistently in the 130's psi on all tests with my cheapie compression gauge. Cylinder #4 was 75 psi cold, 85 with oil added and 80 psi after running, telling me there was a leak in the valves, not the rings or cylinder on #4. I checked the torque on the cylinder head and all bolts were tight and to spec. There are no air leaks around the cylinder head or gasket area. So, off with her head-I ripped her down to lower end last night. I knew the chamber of cylinder #4 had some pitting and corrosion which came with the bike. I did lightly lap the valves with rough and fine compounds when I rebuilt the motor.

#4 on the right, note the pitting.

What I discovered was some of the pitting and corrosion was also in the inlet valve seat of #4, allowing for a slight leak, causing the low compression reading. In a dark room, I shined a strong flashlight into the inlet and exhaust ports and discovered two tiny light leaks on the inlet valve seat, the culprit of my compression leak. If I did it right the first time, I would not be doing this now.

I am meeting with a machinist friend today who has the proper sized valve seat cutters. Hopefully, we can lightly cut the valve seat in order to remove the two small areas of pitting without having to replace the whole valve seat (time and $$$$).

As long as I am at it, I am replacing the kick start quadrant with a slightly used one with better splines than my original.

With 4 cylinders of even compression I should have an easier time dialing in and synching the carbs and fixing the idle problem. I'll post my results, stay tuned....
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