Topic: how do I fit the plenum chamber

[malcolmgb]

ok got my CB400F up and running fine, now what is the best way to fit the plenum chamber between the carbs and air filter box? do I have to remove the bolts holding the box and move it back out of the way somehow?
Also does anyone have pictures of the correct routing of the float bowl overflow pipes & carb breather pipes.

[Gordon]

If I remember correctly from my days with the 400F, the air box has to go in before the carbs.  Probably not what you wanted to hear since your carbs are already installed.

Failing that, a large rubber mallet can work wonders!

[nickjtc]

Hold your tongue just so, make sure that the vibes in the shop are positive and that Jupiter is aligning with Mars, and it will all go back together with no problem.

Speaking kind words to the bike before starting helps too.

[cmorgan47]

here's how i do it (several times over the last month)

take all the boots out of the "plenum chamber"*
put the carbs on
put the "plenum chamber" on the air box
start with the middle boots and work your way out.  this part blows, but it's the easiest way i've found.


*  never heard that word before.

[supersport_CB400F]

I think this is correct Mal, I can’t think what else those clips are for., sorry about the photos but it’s an awkward place to get the camera.

[Honda CBer]

is that frame powdercoated? it is gorgeous...

[dusterdude]

yea,that sucker sure is clean

[supersport_CB400F]

is that frame powdercoated? it is gorgeous...

CB, yes it’s powder coated 3 years ago and that photo was taken today, no rust came back and it’s hard as nails also!…. that stuff gets my vote….cheers

[supersport_CB400F]

yea,that sucker sure is clean

dd did you find any old bushing’s? I know it's clean but it won't be when I get to ride the dam thing 

[malcolmgb]

here's how i do it (several times over the last month)

take all the boots out of the "plenum chamber"*
put the carbs on
put the "plenum chamber" on the air box
start with the middle boots and work your way out.  this part blows, but it's the easiest way i've found.


*  never heard that word before.

can you confirm please;
take the 4 carb rubbers out of the plenum chamber and fit to the carbs, then put the plenum onto the air filter box, then locate the 4 carb rubbers into the plenum (inner 2 cylinders first).

[malcolmgb]

I think this is correct Mal, I can’t think what else those clips are for., sorry about the photos but it’s an awkward place to get the camera.

thanks for the pics Dave but I think my pipes have been shortened, they just reach down to that clip and seem close to the chain.

[Tim2005]

Here's how I do it- an alternative method...

1. Make sure your rubbers are soft and flexy- or soak them in a bucket of very hot water for a bit if not.
2. Fit carbs to bike. Fit tank & fill carbs with fuel to make sure no leaks. Remove tank. 
3. Slide back the big oval metal sleeve into the airfilter housing
4. Work the plenum chamber c/w all 5 rubbers (yes, 5, big one on the back too) & clips in from the right. When it's in place check everything's still attached properly.
5. Attach it to carbs (turn up radio to drown out the language). Tighten carb clips.
6. Push the metal sleeve forward & engage sleeve rubber, fit clip. Leave radio turned up.
7. Fit breather tube to bottom of chamber

Takes anywhere from 15 mins to 90. For added excitement, snap off a centre exhaust stud and drill out the remains.

[malcolmgb]

3. Slide back the big oval metal sleeve into the airfilter housing

6. Push the metal sleeve forward & engage sleeve rubber, fit clip. Leave radio turned up.

I don't have a sliding sleeve, my air filter box seems to be 1 piece.   

[Tim2005]

You should have one- have you got the parts book (or find it on the hondaforfun site) - it's "guide air duct 17235 333 000" . Without it, there's little point in fitting the plenum chamber as you'll be effectively running on iopen carbs anyway.

[malcolmgb]

You should have one- have you got the parts book (or find it on the hondaforfun site) - it's "guide air duct 17235 333 000" . Without it, there's little point in fitting the plenum chamber as you'll be effectively running on iopen carbs anyway.

sorry my mistake  I have just checked it does have one, I thought it was all part of the air filter box,  I now have to find out how to remove it, It doesn't move at all in the rubber moulding.

[cmorgan47]

can you confirm please;
take the 4 carb rubbers out of the plenum chamber and fit to the carbs, then put the plenum onto the air filter box, then locate the 4 carb rubbers into the plenum (inner 2 cylinders first).

i put the chamber on the airbox without the boots
then put the carbs on the intake manifold, again with out the boots
then put the boots into the chamber--pain in the ass, may require use of a screwdriver or something to jam them in
then attach the boots to the carbs
finally, tighten all the hose clamps down

[malcolmgb]

thanks for all the advice, everything is now ready for fitting, all I need is a calm moment in my life 

[supersport_CB400F]

thanks for all the advice, everything is now ready for fitting, all I need is a calm moment in my life 

You’ll never get one of those with a 400 Mal…..this bloody thing of mine is kicking till the end....but I'll win 

[malcolmgb]

Finally done it, after about 4 hours in total over the space of 4 days and numerous attempts and methods. The final attempt was about 30mins which involved my mate taking a call from his work at a crucial stage.

The method I used in the end was;

1 - remove boots from chamber and soak in hot water
2 - fit boots to carbs 2 & 3 and tighten clips
3 - fit boot to chamber position 4
4 - slide chamber into place and fit boot to chamber position 1
5 - push boots 2 & 3 into chamber (not easy) push boots onto carbs 1 & 4 all at same time.

It was a 2 man job as well.

I'm going for a lie down in a darkened room now

[cmorgan47]

curious why you fit the 2&3 boots to the carb first.  i always found it easier to get all the boots into the chamber first then stick my hand through the airbox hole to jam all four onto the carbs.  took some wiggling and shoving, but easier than getting them into the chamber once they're on the carbs, as those flanges are a pain and i kept pulling the boots off the carbs if i put them on the carbs first.

[supersport_CB400F]

I’ve never had a problem with fittings and I’ve never done all that soaking and two people thing  pheww I’m exhausted just reading …well at least the bugger’s are on! 

Are you sure the rubber mount on the head is the correct order they need to be fitted the correct way around,  they have numbers top and bottom so # 1 can be put on as 4 and 2 can be fitted as 3 and it makes a big difference. 

[malcolmgb]

I’ve never had a problem with fittings and I’ve never done all that soaking and two people thing  pheww I’m exhausted just reading …well at least the bugger’s are on! 

Are you sure the rubber mount on the head is the correct order they need to be fitted the correct way around,  they have numbers top and bottom so # 1 can be put on as 4 and 2 can be fitted as 3 and it makes a big difference. 

the carb mounts were fitted when I got it, not sure if they are right but carbs went on no problem, the chamber rubbers felt quite hard when cold that is why I soaked in hot water.

you have me worried now about whether the mounts are right, I will look at first light tomorrow, will it do any damage if they are on wrong or can it be left until next strip down possibly over winter.

[supersport_CB400F]

I  dont think any damage can be done but it just makes things a PIA when fitting….leave them on till your ready I would recomend.

Dave

[malcolmgb]

I can't see the numbers, where exactly are they, can they be seen once everything is in place.

[supersport_CB400F]

I can't see the numbers, where exactly are they, can they be seen once everything is in place.

In the blue circle mal 2&3.