New (to me!) '77 CB400F - US model

[mattsz]

AshimotoK0 - many thanks for those links! I actually have all those downloads already.  I like to have print materials to read and work from, so I purchased the Clymer.  I may try to print out the "official" Honda manual, or sections of it at least.

I must admit the Kawasaki service manual for my 2000 W650 is great!  Lots of information, great diagrams and clear photos... but of course, there's still errors and omissions... nothings perfect, I guess! 

[mattsz]

Stacking up questions here...

I've got one key, "opens" everything.  It's very basic, by the looks of its cutouts.  I could probably buy a blank and file a new one freehand in about a minute.  But, does the 3-digit number on the key imply I might be able to order a new one?  Or, perhaps might I have been able to in 1977?

[Bryanj]

Yes there are a few suppliers working to number

[mattsz]

Does the number suggest a certain key "blank" size or shape, or does it actually tell the cut pattern?  I've seen some other key threads, usually involving fuel tank access or ignition problems, with key numbers mentioned that have more than just three digits, and usually some letters as well...

[Bryanj]

The older Hondas used to start with a T or H but later ones just have numbers and can be 3 or 4. I think there is a firm called something like "hondakeys" on ebay who should be able to tell you if yhe number is ok. In theory there should be a number on the seat lock if you take it off and also on the ignition barrell if you take that off.

[mattsz]

Thanks Bryanj!

[zebedee85]

The rubbers connecting the carbs to the airbox should be nice and squidgy. If they're not then you may need to remove the airfilter assembly to give yourself enough space to wiggle the carbs free, this is the case on the 550f. warm them up, try lots of penetrating fluid around the rubbers (someone may chip in and not recommend this, but i find it works)

i found the 400f carbs quite tough even with good movement in the airbox rubbers, lots of easing, patience and sore hands.

[mattsz]

Thanks zebedee85!

The rubbers are pretty hard and "unforgiving."  If by the airfilter assembly, you mean the box the filter lives in - unless I'm mistaken, it seems like removing that is a major job due to all the electrical components mounted to the left side of it.

I was able to pull the airbox-side rubbers from the carbs, but I still can't see how to gain enough room to pull the carbs away from the engine-side rubbers.  Maybe some WD-40 would be safe to try - not to gain room, obviously, but to ease the movement...

I'll keep at, my hands aren't all that sore yet, so obviously I'm still not doing it quite right... 

[K2-K6]

I can't find it with search on here, but I thought that the more 400 experienced owners may unbolt the airbox and just move it back in the frame to allow more room.

Your hands do end up a bit scrappy doing things like this though 

Any heat you can get into them helps with flexibility.

[zebedee85]

the carbs are not seated that far into the manifold-side rubbers, there is 'just' enough clearance to pull the carbs back, push them down and then pull out - i think the side you pull them out matters too if i recall correctly.

[Nurse Julie]

I find it easiest to remove the air filter, undo the big clamp on the air duct guide, remove air duct guide by pushing the guide back into where the air filter was. Loosen all clamps.Pull back on cleaner chamber, this will remove the rubbers attached to the air chamber from the carbs. Then remove the cleaner chamber completely from the off side of the bike. The carbs then pull out of the carb insulators. Remove complete carb bank from off side of bike. Reverse to refit.

[mattsz]

I find it easiest to remove the air filter, undo the big clamp on the air duct guide, remove air duct guide by pushing the guide back into where the air filter was. Loosen all clamps.Pull back on cleaner chamber, this will remove the rubbers attached to the air chamber from the carbs. Then remove the cleaner chamber completely from the off side of the bike. The carbs then pull out of the carb insulators. Remove complete carb bank from off side of bike. Reverse to refit.

This is the approach I'm trying - but I can't seem to get the air duct guide to budge.  Nothing seems to move in there, and it all feels like hard plastic rather than rubber.  I'll investigate further...

[Nurse Julie]

It's just the metal tube that links the  two that you need to push through. It can be a bit tight. Have you undone the really big clamp holding the rubber around it ?

[Nurse Julie]

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[mattsz]

It's just the metal tube that links the  two that you need to push through. It can be a bit tight. Have you undone the really big clamp holding the rubber around it ?

I was going to write: Yes - all clamps are loosened, the big one removed completely.  I think my main problem is that the rubber bits are hardened up - I'll try to warm them up and maybe give them a massage.  Oh boy, please don't tell my wife about this!

But now I see your very helpful photo - the rubber that holds the air duct guide feels almost like the plastic of the air chamber, so I expect resistance.  But I'll do my best to work the guide backwards out of the rubber seal.

Part of my problem was, the parts diagram make is look like the air duct guide goes between the rubber seal and the air chamber - rather than the air filter cavity side, which your photo clearly shows.  Do you ever use any kind of lubricant to help ease parts along old rubber?