Topic: Stock air box questions (CB500)

[Scott S]

 Some of the parts of my stock air box were damaged or missing. I think I've collected enough stuff to re-install it, but have a few Q's....

 Look at this pipe at the bottom of the air box. It appears to be copper that someone bent into shape. I looked at the parts diagram, but can't tell exactly what the stock attachment looks like. Anyone have a good pic of what's REALLY supposed to be there?


 And the hose....I cut it off when I was fitting pods/breather, but it's about 24" long with a ~10mm i.d. It seems thinner walled than the breather hose I see at Pep Boys, etc. Any suggestions on a good replacement?
 It appears it was routed over the air box, down the back and into the copper pipe, originally.

[bryanj]

The pipe from the top of the engine just goes down behind the cases and is left open to air (ends in about the same place as the carb drain pipes)

The one from the bottom of the air box is originaly moulded rubber and ends open again to alow any fuel/water in the airbox to drain out

THEY SHOULD NOT BE CONNECTED TOGETHER

[TwoTired]

I agree with BryanJ.

I'd like to add that the plenum box drain tube was a reduced diameter molded tube, with a bit of open cell foam stuffed into the end of it.  This limited the amount of air bypassing the air filter yet still allowed overflowing carbs to not pool gas in that plenum.

Cheers,

[Scott S]

 Thanks, gentlemen! Excellent information.

 I'll have to see if the breather hose I have can be routed the correct way. It's thin walled and more plastic than rubber. It tends to kink at sharp bends. I guess it would be fine to leave that breather filter on there, huh?

 It looks like the part I need to replace the copper tube is still available thru Honda; "SKU: 17335-323-000
TUBE ASSY., BREATHER (Honda Code 0253690)"
 I'll call the local dealer today and see if he can get it for me.

 I'd still love to see some pics of the stock set-up, just to help me get this all figured out.

[Scott S]

 Anyone? It would be real helpful to see the size/routing of the breather hose....

[SohRon]

Here are a couple of shots from a 550, but I think it's the same as a 500...





The hose just runs down between the carbs until it makes its connection with the airbox.

The airbox and plenum share a similar drain hose as shown here:



The hose running from the bottom of the airbox must be plugged. Here is a discussion of that:

First off, an update on the Airbox drain tube discussion. This tube originally had a rubber cap that fit over the end of it with a split that could be pressed open to drain condensation or fuel from the tube. Here is a pic from the Honda shop manual:

While this cap/tube arrangement is no longer available (at least, not that I could find), it has been suggested that a substitute may be made by using the longer plenum drain tube (still available, and the same size and shape tube but without the cap), cutting it to length and adding a plug to the end. If I understand it correctly, the reason for the plug (and the original capped tube) is that we want air coming into the filter from the intake under the seat, not from the road surface. It does make sense. I found a small plastic plug (inset on this pic) that fits tightly enough so it won't fall out, but can be removed for maintanance, and plugged the tube.

Many thanks to Two Tired for helping me understand how this system works. I appreciate this kind of help; none of this is made clear in any of the four (Chilton's, Haynes, Clymer and, of course, the official Honda book) shop manuals I've been using for the restoration. It's these small details that can break a project.

Like I say, this is from a 550, but I believe they're the same.

Hope this helps.

[Scott S]

 Thanks, that helps. The 550 air box has a connector for the hose. The 500 does not, but otherwise looks the same. I can figure it out from here.
 Just a couple more parts to be delivered and I can re-install the factory air box!