What's this hole / tube for?

[Nurse Julie]

Hi Chaps
On the back of my engine, just above and below where the crankcase splits at the same level as where the swinging arm sits, there is a long horizontal hole, or tube in the engine casting. Either side are bolts joining the bottom of the engine to bit of the engine on top but between these bolts is this tube. At the moment the drain tube from the bottom of the air filter case is routed through this tube but not only does it not look right but the angle of the tube is so acute it crimps and occludes the tube. I have worked out that is not correct and have re routed it but what should be in that tube, if anything?. Sorry, tried to take a pic but so tight in there even with swinging arm out that nothing really showed.
Ta in advance
Julie

[tom400f]

I know the orifice to which you are referring.

Mine's pretty stock so I'll take a look for you this eve. I've had the carbs off and fitted a new air box filter thingy (the one in the bottom) so I may not have replaced all those tubes exactly as they came off. Back later...

[tom400f]

Hi Julie

The pipe I have routed down this tube is the one from the bottom of the inlet manifold. Fore/aft is about lined up but there is a slight left kink required to pass it through, though nothing serious.

As you say, if you've struggled to get the pipe from the bottom of the airbox down there then that is much further back. For that, mine just goes in front of the swinging arm. See pics - again as you say difficult area to photograph.

Cheers
Tom

PS - had another look - when the airbox tube emerges from the other side of the s/a it cunningly passes through a guide secured under the centre stand left side pinch bolt (hope you have that - heard they are very expensive to replace  ). It's a very long pipe and has a pinch-drain affair at the bottom of it.

[Nurse Julie]

Hi Tom.
Thanks for looking and the pics. Yes, I do have all the original guides which is handy. It must have been the PO that stuffed the pipe from the airbox down there but the end was not attached to the airbox, it was only when I tried to attatch it to the plastic tube on the box that I realised it would kink. I will need to have a good look at it again tomorrow as I think the pipe is actually upside down, or even the wrong pipe as the pinch drain is at the top not the bottom !!!!.

Regards
Julie

[tom400f]

This is called "doing a Simon"

Thanks to Ash for posting the original Honda manual from which this is clipped

[Nurse Julie]

Hi Tom.
Ah ha, now I can see with the enlarged pic. Right, there is no pipe coming off the bottom of the inlet manifold, I can see where the pipe attaches and that would go straight down through the hole I was asking about. But.....no spare pipe in sight so I think that has fallen off in the past. Then the pipe coming off the air filter case would go down almost horizontal through the guide under the centre stand pinch bolt. That all makes a bit more sense now. I think I just need to buy a new pipe from the inlet manifold and a new pipe with the pinch drain for the bottom of the air filter case.

Thanks very much Tom, very helpful

Regards
\julie

[Nurse Julie]

Just looked on DSS and the drain pipe from the air filter box with the pinch drain at the bottom is now an obsolete part. Does anyone know where else I can get this from?. Its Part No 17358-374-000. They still do the breather pipe from the bottom of the air inlet box which is handy as that's the one I'm missing completely.
Julie

[Trigger]

Just looked on DSS and the drain pipe from the air filter box with the pinch drain at the bottom is now an obsolete part. Does anyone know where else I can get this from?. Its Part No 17358-374-000. They still do the breather pipe from the bottom of the air inlet box which is handy as that's the one I'm missing completely.
Julie

measure the outlets and order Nitrile rubber smooth pipe

[AshimotoK0]

You could try Ian (Boggieman) on here Julie, he sold quite a few 400/4 parts earlier in the year.

http://www.sohc.co.uk/index.php?action=profile;u=4731

Ash

[ka-ja]

Hi Julie,
           Is this the one CMS Holland    Ken

             http://www.cmsnl.com/honda-cb400f-england_model14639/tube-breather_17335323000/#.VKb-tMn0fjI

[Nurse Julie]

Hi Ken.
Thanks for that. It is the correct part No. but it seems to not have the pinch drain on it anymore, maybe it's one of those things you don't really need.Why have a pinch drain when you can just let is come out with gravity instead
Regards
Julie

[steven400/4]

i thought the one at the bottom of the airfilter box was the only one that had the pinch slit at the bottom the one on the air chamber was just a hole ??

[tom400f]

That's the one Julie means, Steve

I bought 17335323000 from DSS - it has no pinch drain but since only the upper part was perished I used only that (or some such memory anyway). No idea why there is a "valve" in it at all. Perhaps to keep the crap out as there is likely no pressure or even some suction...

[Nurse Julie]

i thought the one at the bottom of the airfilter box was the only one that had the pinch slit at the bottom the one on the air chamber was just a hole ??

Hi Steven.
Yes, that's what I'm saying. On my bike the one with just the hole in the bottom that should be coming off the inlet manifold has been put on the bottom of the air filter box by someone in the past in error, there is no pipe at all attached to the bottom of the manifold. So all I need to do is swap the one with the hole over to the inlet manifold and obtain a new one with a pinch drain for the air filter box.
Regards
Julie

[steven400/4]

ok i can look in my stash to see if i have an old one if you get stuck but not sure i there is any in the boxes