Topic: CB350f Airbox and Carb Fiasco

[karateisland]

Well, it's not really a FIASCO, but there is more than one problem.

Reading the guide on Honda Hobby for removing the carbs, there is one step in particular that I get stuck on:

Now here is the tricky part. There is a metal insert ( item #5 Air Duct Guide see page 70) that connects the two airboxes and it will have to come out. The duct has a flange on it that is in the rubber bit (item #6  Air Cleaner Element Seal). I usually pry the rubber edge with a screwdriver that I bent 90 deg. You can use what ever you have as long as it is not sharp.  When you put this back in put the metal piece in the rubber and use a little lubricant and pop the rubber in to the hole with the metal already in it. Takes a bit of force but if you wiggle it then it is not so hard.

The issue is that the manual he is referring to is no longer on the page so I am having a devil of a time getting that airbox off. Since I couldn't figure out what he meant, I pulled back the airbox with a strap as I'd read about, but the carbs still wouldn't budge.I even tried boiling water and a hair dryer. No luck. I think getting the airbox off may give me a bit more space. I doubt these carbs have ever been taken off before.

Would taking the airbox off help? Any other ideas or do I just keep rocking and pulling? My arms are pretty sore already!

These carbs are going to be the death of me.

The last thing: I noticed that there is a hole in my airbox about 66% the size of a dime. Do I need to replace it? Is there something else I can do about this? The bike was not running when I got it (I know, I know), so I don't know if this would turn out to be an issue.

[rboe]

I just did this. To remove the carbs I took off the throttle cables. Removed that flexible manifold that connects the airfilter box to the carbs (it was still pretty flexible so compressing it helped a lot). Loosened the four hose clamps from the carbs, the clamp to the air box, wiggled a lot and pulled it out on the throttle side.

That left the carbs on the isolators. Had to wiggle them up and down while pulling it back. Was a dickens but they came off. Install was much easier (had amor-alled them).

I did not touch the air box that holds the air filter save to remove the filter and reach in to help the manifold get back on when it came time to reinstall it.

Historicly I have a #$%* of a time with the carbs and the isolators.

[tomkimberly]

As Rboe said. The 1st time is always the hardest.

BTW, be very careful if you use a pry bar, the fins on the cyliners break easy. I like to use a wooden stick. Hint: (steal your wifes broom).

Tom

[karateisland]

Got it off! Thanks guys. The broomstick was an inspired idea. The carbs are finally off.

But there's still the issue of the hole, which is not in the airbox (I was having a tough time figuring out what the parts in that area were called), but the manifold. It doesn't seem to me like the hole should be a huge issue, but I'm not sure.

Is it worth replacing? Or can it be repaired? Should I even bother?

[rboe]

I'd look for a replacement as a first option (the hole will let in unfiltered air)).

Plan B, patch with RTV. Maybe inflate a ballon in side the manifold, use plastic sandwich wrap (saran wrap) as a mold for the outside. Should be flexible enough to last a couple off and on's.

Plan C. Some talented folks can weld patches on plastic (body shops?) so that may be an option for you too.

[tomkimberly]

I hope your wife did not catch you with her broom.   

Glad you got them off.

Do you mean one of the rubber tubes between the carb and the air box or between the carb and the engine has a hole? Is the hole threaded? It could just be one of the sync screws is missing. Pictures of course would help.

Tom

[karateisland]

Tom--no broom troubles here. It was the garage broom. I was more worried about the teapot and the hair dryer I had in the garage. Luckily, I got out unscathed.

The bike is in the garage and I am still in my bathrobe at the moment, so I'll show you a picture of the same part on ebay. I am referring to one of these:
http://www.ebay.com/itm/CB350F-CB400F-NEW-Air-cleaner-Chamber-/180902516198?_trksid=m7&_trkparms=algo%3DLVI%26itu%3DUCI%26otn%3D3%26po%3DLVI%26ps%3D63%26clkid%3D9198899746075309632&_qi=RTM1084481#ht_500wt_1200

There is a hole beneath the four tubes on the carb side. If it is letting in unfiltered air, I should probably get a new one but I had a bit of sticker shock looking at them on the internets.

Does anyone know a good place to source this?

[tomkimberly]

That's a drain hole, hook up a piece of tubing about 12 inches long and it should have a plug in the end you can remove and drain any fluids that accumulate evey 3 months or so.

Tom

[lucky]

Get a workshop manual.

[karateisland]

You're right, Tom, a picture would have been better. I will remember this in the future.

The hole looked like it had been melted in, was definitely not supposed to be there--so it wasn't mentioned in any shop manuals I have. I managed to find a cheap enough replacement part for it so I sprung for that.

[TwoTired]

That's a drain hole, hook up a piece of tubing about 12 inches long and it should have a plug in the end you can remove and drain any fluids that accumulate evey 3 months or so.

It should NOT have a solid plug in that drain tube.  If the carbs overflow, that drain keep gas from puddling in the inlet chamber.  (Fire hazard, or hydro lock of a piston danger.)  So, use some open cell foam instead, that will let the gas out, but not allow much air to get in.

[lucky]

The fact that the hole was not shown or mentioned in
 workshop manuals is valuable information.

It means it was not a factory design.
And that is helpful information.
Sometimes what is NOT shown, is just as important as what IS shown.

[LesterPiglet]

This should help identifying things.

http://www.cmsnl.com/honda-cb350f-four_model14341/

[tomkimberly]

The fact that the hole was not shown or mentioned in
 workshop manuals is valuable information.

It means it was not a factory design.
And that is helpful information.
Sometimes what is NOT shown, is just as important as what IS shown.

Chill dude.

[rboe]

You're right, Tom, a picture would have been better. I will remember this in the future.

The hole looked like it had been melted in, was definitely not supposed to be there--so it wasn't mentioned in any shop manuals I have. I managed to find a cheap enough replacement part for it so I sprung for that.

So you DO have the drain hose too?

Ya, I got sticker shock myself. Dang clean new unit though. Very tempting.