Learn me CB400F

I'll just cut right to the point this time–I've just received my next two-wheeled project! Here it is:

Sorry for the semi-horrible pictures.

It's a 1975 Honda CB400F. My dad has had it for years, but hasn't really ridden it. He's always liked it, but found it to be a bit, uh, small and uncomfortable for a person of his stature. Now that he's bought a new Triumph Bonneville T100, we've been riding together. He finally realized that I love the Honda, so now it's mine!

As far as modifications, it's basically stock. My dad put separate K&N filters on instead of the airbox, and I think the jetting has been messed with a little bit. It's also sitting on Konis. Thankfully, nothing's been done poorly.

Onto the issues. There aren't any, really, just the problems that come from sitting in a garage. The front brake drags slightly occasionally, the ignition (the keyed cylinder, not the coil) sometimes doesn't make contact when turned, and the bike stutters when suddenly given full throttle, or occasionally when cruising at half throttle. It still rides great, though, and everything else is perfect. Obviously it could use a good bath, but the paint and decals are all good, too.

So, the questions:

Where do I buy a new ignition cylinder?

Where do I buy carb rebuild kits?

What causes the front brake to hang occasionally? Do I just need to pull the piston and clean the bore, or is it a common problem with these bikes?

Dad has good taste!

Your in luck. Of all the vintage japanese bike brands, Honda has the best parts availablility. If your local Honda dealer can't get it, try bikebandit.com.

Sounds like you are in need of a caliper rebuild. See this: http://www.cb400f.btinternet.co.uk/webrake.htm

Check the internetz. There are a couple of owners groups and owner build diaries.

Oh, and get a subscription to a magazine I recommend Motorcycle Classics.

I always liked them, they were pretty little bikes. Is the exhaust aftermarket? It looks like a couple of the pipes cross over each other, originals had them all side by side with a sexy wiggle in the middle. :)

First place to check for parts is the dealer. Honda is pretty good about supporting older models, particular ones that were popular like the CB400F. You can either try the local brick and mortar store, or go online - there are many choices there, including www.bikebandit.com. If nothing else you can use them to look up the part numbers - the ignition looks like it's pretty expensive but carb parts aren't too bad.

Once you have the part numbers you can also hit eBay, there's a lot of NOS stuff floating around out there. One more choice is a motorcycle salvage yard, one of the biggest is Sport Wheels in Minnesota: http://www.sportwheel.com/

Also, chances are the ignition was used on a number of different size Hondas over a period of years, so you may be able to find a suitable replacement from a different bike.

edit: this is sort of off topic, but here's your trivia for today. Peter Egan's first published story (in Cycle magazine, back in about 1976) was about how he rode his CB400F from Wisconsin to New Orleans and back, in order to buy a pound of chicory coffee. I still have that magazine sitting on the shelf.

I had one of those for years. They are terrific little bikes and among the most collectible Japanese motorcycles.

The first thing that I was going to mention was that most people ruin them with K+N filters, but as long as the carbs have been properly rejetted and the exhaust has been freed up you should be all set.

I used to disassemble the brake caliper every Spring. It would freeze up the first time I'd squeeze the brake lever after sitting all Winter. I was broke, so I'd just clean up the cylinder and piston with some steel wool or Scotchbrite, clean it with brake cleaner and lube it with brake fluid. But don't listen to me; do a proper rebuild if you can. A braided steel brake line wouldn't be a bad idea.

And, more than any other bike I've ever ridden, these things can really benefit from a steering damper. They want to turn and can be a little twitchy.

The original headers are a thing of beauty.

For some reason I read this as "Learn me FZR 400" to which I knee-jerk respond "MOTHER OF GOD!!!! I NEED ONE OF THOSE... and to lose 60lbs so I can ride it"

Since this thread is obviously not about that bike at all... carry on.

Oh, I almost forgot. The electrical connections tend to corrode, causing intermittent failures and sometimes the fuse boxes melt. Just pull the fuses and clean the contacts with a file or small wire brush. Do the same with any ground or bullet connector you find. Even if you have a fuse box meltdown, you can just replace it with a small generic one that uses easy to find blade fuses.

The seat is a lot more comfortable if you remove the strap.

It looks to me like your bike has the taller handle bars of a '77.

You can fix almost anything on that bike with the small tool kit and owner's manual that Honda put under the seat.

Sweet stuff Tom.

Ill be watching this one closely

Good luck

Great info so far, I knew GRM would deliver!

I'm planning on doing everything right, and I don't plan to butcher anything up.

I'm fairly sure (after seeing other pictures) that the exhaust is an aftermarket piece. Can anybody tell if it is? It wouldn't surprise me at all if it was an aftermarket piece.

Also, what's the consensus on cafe-racer style bars? Besides looking a little "old fashioned," the current bars feel real high to me. Of course, that may just be from all the dirt-bikes.

Front brakes on these are a pain in the backside. Basically you'll have to periodically remove the 'arm' that carries the caliper from the pivot and regrease the pivot so the whole assembly can move around OK. Also make sure you get a modern pad material, with the older pads the brake basically doesn't work in the rain.

A good friend of mine who's a bit of an expert on these generally prefers the original airbox and suggest they tend to run better with the 'box than with individual filters, even when the carbs are set properly and the filters are not made from carpet underlay[1].

Seat pans crack and rust on these, if you have a good pan make sure you keep it that way. Most of the aftermarket replacement seats are horrible and might as well be made of wood...

Oh, and it's a Honda from the horrible camchain tensioner period. The automatic camchain adjuster basically doesn't, so make sure you give it a little help on a regular basis.

They're neat little bikes and handle a lot better than most Japanese bikes of the period, which isn't bad for a parts-bin special. In the UK, they're one of the very few collectable Japanese bikes.

[1] Not kidding. We were trying to figure out why the GT380 he had just bagged on the 'bay didn't want to run right. Took us a while to find those home-grown filters that worked so well that they didn't let anything through, including air.

Tom Suddard wrote: I'm fairly sure (after seeing other pictures) that the exhaust is an aftermarket piece. Can anybody tell if it is? It wouldn't surprise me at all if it was an aftermarket piece.

It is - look at the picture of the yellow one, that's wearing an OEM or OEM-style exhaust. Most aftermarket pieces don't replicate that too well, but original parts (especially the headers) are getting harder to find. Of course harder to find also means more expensive...

Tom Suddard wrote: Also, what's the consensus on cafe-racer style bars? Besides looking a little "old fashioned," the current bars feel real high to me. Of course, that may just be from all the dirt-bikes.

This one's got the European bars on it (as does the yellow one in the picture above):

http://www.carandclassic.co.uk/car/C147082/

IMHO they're much nicer to ride that way (I've owned one in the past and ridden a couple) compared to the US-market "ape hangers".

The friend of mine I mentioned in the previous post breaks bikes as a hobby business - he's in the UK and I might be able to hook you up with a set of European bars if he's got a set. PM me if interested and I'll find out - shipping isn't going to be cheap from the UK, so it depends how badly you want them. I'm 5'11" and I find the original European bars a very good fit if you intend to ride the bike for a few hundred miles in one go.

Edit: Forgot to mention - inspect the rear fender very closely, they rust like nobody's business and they're unobtanium. As is the front IIRC, but that's easier to find. If the one on your bike isn't plastic but the original chrome and looks like it's starting to go, get it rechromed ASAP.

Also, they're supposed to have a little chrome lifting handle so you can put it on the main stand. Those are also unobtanium, although most parts dealers will be able to supply you with an 'almost correct' one.

For spares you might also find http://www.davidsilverspares.co.uk/ and http://www.cmsnl.com/ useful as both stock tons of OEM spares that Honda won't be able to supply anymore - a lot of the 70s Honda stuff is NLA from the dealer. Both are in Europe, though, so shipping across that little puddle outside your front door might be a tad expensive.

You definitely have an aftermarket header. Sorry

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If you want a lower bar, try to find an original 75-76. They're just right on those. It's just a PITA to snake the wires through the inside of the bar. I put a Clubman bar on mine and never really liked it.

Early bars:

I agree that they run best with the original airbox. They just don't look or sound as good as the open filters. If I ever get another, I'll keep the stock setup.

Like any old multi-cylinder motor, these are easiest to tune with the stock airbox, but there's no reason the carbs can't be setup with individual pod filters. It just takes some time and know-how. I'm willing to bet there are resources on the internet to steer you in the right direction.

Other advice about the front brake is spot on: you can get rebuild kits for the caliper, and that's what you need to do. The master cylinder is a bit trickier, but on this bike, I'd ignore the master cylinder as long as it's not leaking air or fluid.

As for parts, I like cmsnl.com, at least for real OEM part numbers and good fiches (and some parts that are unavailable stateside). BikeBandit uses their own part number system so you can't go and order from anybody else, which is understandable, but still annoying.

Woody wrote: You definitely have an aftermarket header. Sorry

That's okay, I think I like this one better.

My dad says that the carbs have been professionally tuned to work with the new filters and header, so I think all it needs is some cleaning to run perfect. It doesn't ride like it's poorly tuned, just like it's got dirty carbs (aka sometimes it's perfect, sometimes it isn't).

All of the chrome is still in almost perfect shape, rust is absolutely not an issue.

I'll go to the Honda dealer soon to get a caliper and carb rebuild kit. Dad says it already has modern pads.

What's the consensus on clubman bars? They look cool, but how comfortable are they?

Is something like this a good deal, and would it fit this bike?

Also, what do these look like without the rear fender (obviously with a different taillight)?

I wouldn't stick non-OEM bars on them, you're in for a world of electrical fun if you do. The original switchgear routes the cables inside the handlebars which means you'll either need new switchgear as well and bodge that into the existing wiring, or you'll have to get bars that can take internal cables.

If the bars are too low, the ergonomics will be all wrong so you'll need rearsets, too...

BTW, I don't think you need a caliper rebuild kit - most of the brake issues are connected to the swing arm that the caliper bolts onto, not the caliper itself. Take the caliper off, then take the arm with the mounting plate off and make sure they move freely around the pivot. If they don't, hope that you can get it out to regrease it.

I'd leave the rear fender as is, they look badly chopped with it removed as the front plastic half ends under the seat.

Tom Suddard wrote: What's the consensus on clubman bars? They look cool, but how comfortable are they? Is something like this a good deal, and would it fit this bike?

Here's what I can tell you:

I put that handlebar on the same bike. I regretted it immediately, but it was too much work to swap back.

YMMV.

They look good with a different light on the original fender. Drill a hole through the center of your license plate and use the hole in the fender for the lower tail light bracket screw to mount the plate,

CB400F's are cool bikes. About running wire inside the bars: way back in The Dark Ages, bars were known to break in half in the middle where the wires all come out. It happened to me. The OE bars were expensive etc., the fix was to pull the switchgear, file a small relief so the wires could be routed externally then get the bars of your choice. We used to wrap the wires with electrical tape, the more modern way to do that is shrink tubing. Clubman bars have a weird bend and pullback that I have never cared for. I like fairly low/straight bars on street bikes and tall/straight on dirt bikes, myself.

Ignition switches of the era could get water in them though the key slot, causing internal corrosion of the contacts. The fix: good contact cleaner, WD40 and patience. This works best if you remove the switch, although it can be done in place. First, squirt it full of WD40 through the slot, stick the key in and work it back and forth a bunch of times. Now hose it out with the contact cleaner; if you have the switch off and upside down you will see a lot of whitish/brownish goop run out of the key opening. Do this several times, when the contact cleaner comes out clear let the switch dry for a couple of hours. Then shoot a short burst of the WD40 in it so it will stay lubed, it should work fine now.

For the handlebars, you should just get a generic bar Like these BikeMaster models and try them for yourself. I have "superbike" bars for the both the R350 and SV650 and they work well. Well, I've never actually ridden the RD350, but it looks good nonetheless.

NICE SCORE!

You'll want to lurk here: http://forums.sohc4.net/ And join here: http://www.dotheton.com/forum/ Check out TwistedWheels' build, he makes some nice gauge covers too.

I remember an article, I think in "Cycle" magazine about a guy who built a cafe racer CB400 and it was totally tricked out (for the time). Can't think of his name... Mizaki? IIRC it was very much like Mikuni. Anyway, they asked him how much he's spent on it and his response was something like, "On the whole bike...? You've got to be kidding me...." For people of "normal" stature it would be exceedingly cool. Nice score!

Ok, here's where I'm at:

The carb issue is fixed and the bike runs perfectly.

The ignition has been cleaned out, and the bike starts perfectly.

The front brake has been gone through, and now works perfectly.

So, my next question: what kind of normal maintenance schedule should I be following? Oil changes (transmission shares same oil, I assume?), chain lubrication, chain tightening, etc.

Have you found the owner's manual under the seat? Lots of info to be found there.

I have a set of these Electrifix brushes, which are awesome for cleaning up the electrical contacts. Unfortunately, it has been discontinued from Automotion. (Part # 830023). Maybe you can find a similar product elsewhere.

EDIT:

They can be found here:

http://www.cornwelltools.com/webcat/products.php?product=BKBAT01-%252d-ElectriFix-Brush-Set

Tom Suddard wrote: So, my next question: what kind of normal maintenance schedule should I be following? Oil changes (transmission shares same oil, I assume?), chain lubrication, chain tightening, etc.

Oil and filter change IIRC somewhere between 1500-2000 miles with good quality 10W40. I have the vague recollection that the cam runs directly in the head on these so you want to err on the side of caution when it comes to oil change intervals. And yes, the transmission is integrated into the engine and shares the same oil.

Yeah, keep the engine oil changes close since the tranny and engine share common lubricant.

Used to be you lubed the chain every time you rode the bike and adjusted it every week (assuming of course you actually rode every week, duh) but nowadays an O ring chain can fix all that. I found cheap O ring chains at http://motorcycle-accessories.d2moto.com/search?w=chain&asug=chai No affiliation other than Google searching. The tires, check pressure etc every ride.

The clutch lever should have ~10mm of free play as measured at the outer end of the lever, adjust as needed.

I think it has electronic ignition, no maintenance needed other than replacing the spark plugs every so often. For some reason 6,000 mile plug intervals sticks in my head.

If it has points, every 2,000 miles clean/gap/time. If it has points, cheap/easy way to set the ignition timing: you need a very thin piece of plastic (cigarette pack cellophane worked perfectly but that's no longer plitically correct), turn the flywheel till the points open, stick the platic between the points and turn the flywheel till the plastic is trapped. Now pull gently on the cellophane and tourn the flywheel, watch for the mark. You want the cellophane to come loose just as the 'T' mark passes the pointer.

Or you could just use a timing light.