Topic: Honda CB400F - Sort of a rebuild

[Timmy]

Hello!

So, after lurking around on this page and DoTheTon, I decided to buy myself a Honda CB400F. Got a decent price for it 1400€. It went through the yearly inspection with a clean sheet.
The inspection was done by the previous owner and since I don't have my license yet (hopefully have it in a week), I bought the bike without testdriving it. Stupid, maybe. But it revved "fine", sounded alright and so so when I looked at it.
When my father in law drove it home, he said that it only produced like 8 HP. I was devastated. Though the compression was totally blewn, that I hade to rebore etc.
Luckly, I found that it was no spark on 1-4 cylinders. Woho! That means I could solve it.

So I bought a Dyna S ignition system since I didn't want to fiddle with points, and the bike started on first try. All though still only on 2 cylinders. So I started swapping sparkplugs, and then suddenly it ran on 3 cylinders.
Took it for a spin, and it ran better and better. Then on all four! Yes, still need to do the timing correct but got it alright by chance.

Now I have had it standing for 2-3 days. So when I drove around the block yesterday, I only had spark on 3 cylinders again. 4th was dead. Switching sparkplugs again between 3 and 4, starting again. 4th cylinder ran, 3rd was cold. So I have ordered new sparkplugs.

Thing is that I couldn't just sit for a day or two, so tonight I pulled the carbs Really want to go through them and be sure that the jets and needle is clean.
But I have a problem. I'm not 100% sure how to pull that needle and the "tube" it runs through.
Should I remove the hex screws? They are "locked" by some stupid thin sheet metal thingie.


Also, I broke the "plastic" thing that goes between the carburators and keep them with fuel. Is that something you can buy seperatly?

Anyway, my plan for this whole bike isn't quite clear or set in stone yet. All I want right now is to get it running good and crisp, so I can ride this summer at least.
During the winter here in Sweden, I will have some time to do either an engine renovation, or the cosmetics; painting frame, rear seats, cafe cuts, re-wiring and so on.

Oh yeah, and here it is. With a small dent in the tank.

[Bankerdanny]

The tube thing is called a slide.

You remove the slide using the other nut in your photo. Bend down the lock tab (I do this with a small regular screw driver and a hammer, tap very gently) and remove the bolt, the shaft with the arm on it will slide out and you can lift the slide out. The slide is held to the lift arm by 2 screws with very small phillips head screws.

When you slide the shaft out pay attention to how the various washers and spring go on.

[Timmy]

Ah, I wasn't sure if I was gonna mess and do like that.
I'm in between if I should order new jets before I put it back on the bike, since I wanna run pods.

If I do run pods, would a main jet of 80, idle 35 and raising the needle put me quite alright for it to run quite good. Everything else is stock. I'm at sea level.

Also, all the tubes, like the one from the crankshaft - they all go in under the current airfilter. Can I just leave them be, and leave the old air filter still attached?


Can this marked plastic piece be found anywhere? I frecking broke it when trying to separate the carbs. Why use plastic?! The T-connector from where the fuels goes is nice metal.

[Timmy]

I will try to glue the plastic thing with some loctite tonight. Think that'll solve it.

[iron_worker]

Check CMSNL.com for stock of that part.

IW

[Timmy]

I tried CMSNL.com but couldn't find that part. What's it called? Does it have any number?


I cleaned the bowls and jets today, blew the carbs clean with WD-40 and jerked the needle up and down, blowing air to clear dirt. Thinking of removing the needle and check it and the tube it goes down to if there's any problem with them. But they seemed to be in fine shape and no resistance when throttleing. Right now I just want to get them back on the bike, put some the new spark plugs in and get it running on all 4 cylinders again.

When that's done, I need to dynamic time the ignition, and sync the carbs. Gonna check if the valves are correctly adjusted as well.

Gonna add some pictures tomorrow. Pretty late now, so I need to go to bed to not be a zombie at work tomorrow.l

[Bankerdanny]

You should really use carb cleaner to blow the jets clean. Once the slide is out blow carb cleaner through all the jets and various orifices in the carb and make sure that a steady stream or for the small hole on the jets, a thick mist, comes out of all of them.

I'm afraid that I can't really help you with the jet tuning. I always run the stock airbox.

As far as the tubes that vent to the box, yes you can just leave them open, but route them so any oil vapor that comes out doesn't get on the tire. You may need a combination of longer hoses and zip ties.

[Timmy]

Thank you Bankerdanny for the advise!
Gonna do that if I get any problem later on. I just wanna rule out the spark issue first. Couldn't pick up the spark plugs today

See if I can get the time to put the carbs back today.

[Timmy]

Geez. This bike is giving me a headache.

Last evening I cleaned the carbs with YES and WD-40. Just scrubbing light, blowing all the jets with WD-40 and my lungs. They were looking pretty decent and the carbs ran before. I just wanted to double check and sort everything out.
I also benchsynced the carbs, but don't know how much it actually did.

I don't have a garage, and I live in an apartment with my daugther and girlfriend. Hence the cleaning of carbs next to the dishes. And no, I prioritize the bike and carbs before the apartment right now. Girlfriend not that happy, but I'm glad she puts up me and that the whole kitchen stinks of WD-40 and gasoline





Here's where they rested during the night. I gather all my hobbies in one place: hockey, craft beer, motorcycle. To bad the bike doesn't fit


Sorry for not having any pictures of the finished results, but I didn't do the outside that clean. It's a project for the winter. I just want her to run this summer!
Put them babies back on the bike recently. What a fu**ing struggle. And I didn't even manage to get the all the manifold from the carbs into the air-box. Just like one of them. Any tips?
Thinking of buying K&N pods just since that would be easier to put there lol.
Got a nice battlescar:


Anyway, connected everything, turned the key and let the engine turn a few clicks on the start button to pump around the gas. Choke on and BAM! Fired up quite fast.
BUT, it now ran on cylinder 2-3-4. 1st cylinder was cold. 
Kept on reving a little, tuning the idle a bit and went for a short spin around the block. And guess what happen? 1st cylinder kicked in, bike ran like a godess (almost). Still getting to much air due to not all carbs connected 100% to the airbox. BUT STILL! Yeajj.

I guess it's due to a weak spark or something? The black/white cable from the ignition -> 1-4 coil lost some copper wires. Need to re-do that one to be sure.
And as mentioned before, I need to set the ignition. Haven't even done the static one, since I didn't have any lamp to check it with when I attached the Dyna S.

[Timmy]

Connected all the rubber thingies between the carbs and plastic box that goes to the air filter. Pain in the ass.

But it fired up an ran on 4 cylinders. Took her for a spin, and she really pulls! So much that the clutch slips around 7-8k. Guess no one has changed it in years. A lot of years.

Next on the list:

- Re-do the black and white cable shoe to the 1-4 coil.
- Set the dynamic timing.
- Change oil and spark plugs.
- New clutch.
- New air filter (stock or pod, don't know yet)
- Sync them carbs
- Check valve tolerance
- Try stretching the cam chain

I also want to put another exhaust on there, but the thought of pulling them carbs of again for re jetting...Then I'll porb go pods, since that would be easier to put back.

[Mister Gumby]

That's a good woman you have there, letting you rebuild carbs in the kitchen! It gets quite warm in the summers here in Arizona so last year when I was trying to get my 350f rolling, my wife was cool enough to let me wheel it inside.



You'd be wise to invest in a Clymers manual, its always the first thing I always buy when getting a new bike.

[Timmy]

Haha nice. Our apartment isn't big enough to fit the bike and she wouldn't be cool with that. Ah well.

I got me the shop manual. What's the difference to Clymer?



Anyway. I failed my drive up exam Getting a new chance 25/7. Fingers crossed.

Today I changed oil, filter and plugs. The manual said 3 liters, I put 3 liters in and it turned out it was to much. Just above the line. I started the engine just a bit to see that the new ignition setup was OK. Ran it 500 meters and back. Couldn't hurt with a bit to much oil I thought.

Lol idiot me. Luckily Honda made this engine handle idiots like me. The crank case hose puked out some oil right over the air filter. I still needed to change that before, but now definitely.
I made a pipette of a straw and a shoot you use for medicine. Sucked 2-3 deciliters from the engine so the level of oil was under the suggested line.


Does anyone even read all the text, since there's no pictures?
It's a hassle to get the pictures here. Need to email me them from my iPhone to my mail. Upload to Flickr then link them. Not much to see anyway. An oil change

[strynboen]

i have brushed mine 400/550 kab vith battery acid..it kleanes all fine up..then wask in dishvash..and -wd 40..vhen it dryed up

[Timmy]

@strynboen - thanks for the tip. Might be doing a more detailed cleaning during winter. They'll do for now

[strynboen]

be care..it eats eyes and clothes. ..but rust and oxid are gone in minuts

[Bankerdanny]

No project is truly yours until it has drawn blood.

[Timmy]

Bankerdanny, I guess not!

I'm waiting for money and time to make the next moves on the bike. Also to get me the license hehe.

Gonna change the clutch since it slips at high revs.
Probably need to replace/rebuild the damn front brake.
Set the timing and sync the carbs.

Then ride the hell out of it!

Winter is coming...

... And that's when I'll do most of the stuff.