1977 CB400F Super Sport "Give Up"

PHeller

New Member
Just picked this up. Almost all original parts, but not the original exhaust :( - I vow to finish this bike with a sweeping 4-1 exhaust.

I got a spare tank, footpegs, lights, etc.

Currently, the bike doesn't idle or go faster than 15mph.

PREVIOUS OWNER REPLACED OR SERVICED OR FUCTED UP: Fork seals, valve springs?, K&N pods, MAC 4-1 Exhaust, mini rear light, superbike bars, cleaned and rebuilt carbs with below mentioned "mods", replaced key cylinder, reupholstered seat (nicely), new (crappy) throttle and clutch cables (that are crappy).

CARBS: Previous owner drilled "one size up" on a set of drill bits. I have no idea what that means. Needless to say I think the stock jets are kafucted. I'll replace with a set of #85, as I've read that is what is necessary for pod filters alone.

EXHAUST: Previous owner scrapped the original exhaust this past week, deeming it "too beat up to keep"....I disagreed...but the current exhaust is a MAC piece in ceramic coat black. It's not overly loud, so I can't see it changing the flow (or jetting) that much. Hell, it might flow WORSE than stock. Disappointed about this one.

ELECTRICS: Everything works...strangely enough...but the wiring is a rat's nest of wire nuts and electrical tape. Random wires are cut places, and others groups of wires are all connected together. The starter wire is all on its own...running around the bike like someone lost track of the original wire and decided to run their own.

I got all of this for a few hundred bucks.

My inspiration?

Woody's CL350


I'm thinking low, sleek, and built for style, not for speed. I might actually get ahold of a CL360 front wheel with drum, and a few other "back dated" parts.
 

Kanticoy

Mad Science!
DTT BOTM WINNER
Re: 1977 CB400F Super Sport (no pics, no progress, read if you want to help)

Post a pic of her up. I have always wanted to see what a MAC setup looked like. It actually has a better collecter on the pipes than stock so i imagine it would be a good candidate for a race exhaust depending on the can....just curious what they look like. I'll help any way I can. Put her as close to stock as possible and go from there first....especially on the carbs.
 

PHeller

New Member
Re: 1977 CB400F Super Sport (no pics, no progress, read if you want to help)

Well I can't go too stock because of limiting funds.

The condition of the stock air box rubbers is such that I'm tempted to stick with the pods. You may disagree. I'll post pics of the box.

Replacing the exhaust would be a mad expensive proposition, so I'll re-jet according to a better flowing exhaust. Maybe a 90 main? No idea on the low speed jet.

Electrics really worry me. I'll post some pics of that mess, because I'll really need some help there. The funny thing is, as hacked up as the wiring is, the bike still runs.

I rode it down the street and back, shifted all gears, clutch worked, brakes worked...all just very slowly.
 

Kanticoy

Mad Science!
DTT BOTM WINNER
Re: 1977 CB400F Super Sport (no pics, no progress, read if you want to help)

Oh no, I didn't mean make the bike back to stock, I meant put the jetting back to stock. I run velocity stacks on my 400f with a MC Again header, and I upped one jet size for the pipes, one for the velos. I just mean, get rid of the shoddy jets and put good ones in. Rule of thumb is one size for pods, one for exhaust....gets you pretty close to ball park. Do a plug read and see how they're looking...my guess is fouled. And the floats in these little guys LOVE to stick and puke fuel. Get you some anti seize from the auto parts store and put it on the float pin when your putting your jets in. It really helps.
 

PHeller

New Member
Re: 1977 CB400F Super Sport (no pics, no progress, read if you want to help)

What jets are you running? #85? or 90? Stock is 75 I believe.

What about the idle jets? Up or down or no change?

Any pics of yours, Kanti?
 

Big R

Heaven is so far away.
Re: 1977 CB400F Super Sport (no pics, no progress, read if you want to help)

As far as the wiring harness goes: if it's just TOO bad, im sure you could get one from a similar bike and just compare the wiring diagrams for each. They should be almost the exact same (just guessing)
 

PHeller

New Member
Clutch actuator lever is messed up. Clutch is also very stiff. One broken bolt/stud and the other is missing.

What lies under the tank.

Wiring mess.

Lots of work needed.




I tried starting it again tonight. After about 20 kicks it lit up, but would only run under 1/2 throttle or more. Won't rev more than 2,000 rpm, no matter how much throttle.

Won't idle.

Plugs are wet.

I tried timing it as best as I could, but I don't have a timing light so I have no idea on how close that is.

Didn't check the advancing unit, that's tomorrows project. After that, its onto the carbs.
 

teazer

Well-Known Member
DTT BOTM WINNER
That's not a bad start. The wiring may look like it's guts are hanging out like it committed hari kari, but really I's just untidy. That should be easy to tidy up.

Seat is a good place to start but it needs some sort of rear fender. The symptoms sound like jets clogged in the carbs, but we don't know how good the motor is or how old the plugs are. Start with giving a good clean and service it. Clean the carbs, fit good new plugs, check for a fat spark from both coils check compression while the plugs are oput and set the tappets.
 

PHeller

New Member
Ok, so I got the carbs off tonight, which was pretty easy, and I was disappointed at what I found.

The bowls must have been leaking on the previous owner, so he used some sort of sealant to seal them...only it didn't harden and turned to a gooey mess inside my bowls.

So here's the run down:

External Condition: Good, most screws come loose pretty easily. Everything seems to be there including hoses. Discovered PO must have switched the throttle because it only had one cable. There is no return cable on the carb.



Bowls: Gunky with gook. Drain screws were extremely tight (probably because of gunk), and one I couldn't get out...I actually rounded a flathead screw...


Main Jets: Marred and gouged, clogged and two had really messed up seals. They don't appear to be drilled, but who knows.

Pilots: clogged, but otherwise fine.

Carb body (inside bowl): I'm seeing some pitting on the #4 jet holder thing. Is this a problem?


Floats: Here is where I noticed a big question. The float has a nick in it. Are these solid floats? Does this nick keep it from floating?


Throats and slides: Both look good. Some little nicks on the slides, but nothing serious...I think.

 

PHeller

New Member
Last night:

Put carb back together without new jets (crappy seals), without new float bowl seals (let them soak in brake fluid) and aside from a good cleaning, pretty the way it came to me.

Today:

Beautiful morning, so I set off to get some spark plugs.


Get back to the shop, pull the plugs...and find this...

On the left, you'll see a D7EA, D8EA, and then a DR8EA. On the right are the new plugs after idling the bike and running for about 5 minutes with a quick trip down the block.


Yes, you read that, the bike IDLED for a few minutes. I tried running up the street, but it was really bogging. However, it did rev past 6,000 rpm, so this is IMPROVEMENT.

The bowls didn't leak, the bike didn't smoke much considering it condition, and it actually revved like a normal bike.

After running for about 10 minutes the bike wouldn't start again, I think I either flooded it or the jets got clogged again.

So the carbs will come back off, get recleaned, and new jets will be installed. Then we'll try again.
 

Tim

Administrator
Staff member
At least now you're running the right plugs :) You don't want 'R' plugs as they add unnecessary resistance and weaken the spark.

If you're running a fancy electronic ignition, then you want 5K ohm resistor spark plug boots, which often come with the ignitions. Then for sure you don't want R plugs as you've doubled the resistance.

Plugs look better but perhaps a bit 'clean' especially from just idling. Make sure it's not running too lean.

All that being said - don't sweat the carbs / plugs yet.

1 - valve clearances - set these correctly with engine cold
2 - timing - static timing adjustment with test light - also check points condition/gap too
3 - spark plugs - new plugs properly gapped
4 - fuel supply - clean and fresh
5 - air supply - new air filter / clean it

Now you can start the bike and fiddle with carbs. Unless you've done all the 'mechanical' work above first, all the carb work in the world isn't going to help and will end up needing to be redone.
 

PHeller

New Member
Everything above I've done aside from valve clearances.

The intake might affect the running performance, but it won't keep it from running. That's the problem now. It turns over, it fires occasionally, but its not running. I didn't change anything after 10 minutes of it running on its own.

I think the jets that have torn or messed up seals, and the fact there was so much shit in the carbs, probably means there is still major issues with the fuel delivery.

I need to get a feeler gauge.
 

teazer

Well-Known Member
DTT BOTM WINNER
Somehow I managed to miss teh reference to the PO drilling the jets out. The chances of him getting that right are about the same chance as winning the lottery.

Those carbs look more or less OK. Make sure all the small drillings are flowing the same from one carb to the next. I use a can of carb/brake cleaner and blast it down a passageway on carb 1 and then i do the same passage on #2, #3 and #4. That way if one is even slightly clogged I can see the comparison.

While they are apart, take the time to check and adjust the float valves. And then adjust the slow speed air/mixture screws.
 

KrashManhatten

New Member
PHeller said:
Everything above I've done aside from valve clearances.

The intake might affect the running performance, but it won't keep it from running. That's the problem now. It turns over, it fires occasionally, but its not running. I didn't change anything after 10 minutes of it running on its own.

I think the jets that have torn or messed up seals, and the fact there was so much shit in the carbs, probably means there is still major issues with the fuel delivery.

I need to get a feeler gauge.
Not that every one has a problem with the electrics, but make sure the battery is good too, as a weak battery will simulate screwd up carbs.
 

PHeller

New Member
Well I had it hooked up to a car battery for testing and it still gave me a no-run.

Seriously...the seals around the jets are fubarred. Torn and all else. I know the main jets are a definite problem. Whether the main jets are keeping it from running, I'm not sure, but I'll have to pull off the carb to see if any of the sealant used by the PO is still floating around the passages.
 

PHeller

New Member
I've noticed the rear tail seems to have had the stock signal threads stripped out and new holes (i think) drilled next to them, which is a bummer.

Anyone with a CB400F want to post a picture of the tail section of frame?
 

PHeller

New Member
New jets in, I used 85s. Runs pretty good. Idle is surging a bit, but hey...its idling. It also has a very snappy throttle response (despite the throttle wire being rusty).

Now it's gotta be taken apart and fit into the back of my station wagon for its journey north.
 

Erskine

New Member
Dumb question but have you thoroughly flushed the fuel tank out?
The crap in old tanks is incredible. I've found logs, boulders, shopping trolleys, strange petroleum dwelling fish.
You never know whats in there.
;)
 

PHeller

New Member
True, but I've got an inline stone filter on the line, so its getting clean gas...but necessarily "good" gas.

I think I've got a sync issue.
 

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