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Discussion Starter #1
Hi,

I have a '75 Honda CB500T. I removed the side air filters and am putting on pods (it has been jetted accordingly). I want to know if I can remove the breather box.

If I do, what do I do with the small tubes that leave the carb and enter the box?

Thanks!
 

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...I removed the side air filters and am putting on pods (it has been jetted accordingly)...

That was probably the worst thing you can do to a 500T especially if the carbs are stock.
 
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All I'm saying is the stock carbs do not work very well with pods at all. You might find yourself frustrated trying to get the bike to run right.
 

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Discussion Starter #7
The worst would be driving it into a tree.
Gotcha. Like I said the carbs have been jetted for pods. And I found it was having a hard time idling. So I pulled the stock ones off and put on the pods and it's back to normal.

So, back to the original question, can I remove the breather box?

If I do, what do I do with the small tubes that leave the carb and enter the box?
 

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Well if you're adamant on not using the OEM air boxes then there is no need for the breather box either.

Even rejetted you are still going to find that the stock 500T carbs do not run well with pods.

Also I am not sure I understand this bit "what do I do with the small tubes that leave the carb and enter the box?" What small tubes? Got a picture?

 

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Also do yourself a favour and don't throw away anything you removed. Parts for these bikes are getting harder and harder to find as is and you may find yourself needing them later.
 

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Discussion Starter #10
Also do yourself a favour and don't throw away anything you removed. Parts for these bikes are getting harder and harder to find as is and you may find yourself needing them later.
For sure on keeping the OEM parts. I don't have a close up picture. I'll grab one tonight. But here's the gist of it. There is rubber tube that runs out of the carb into the breather box. From what I have read/understand it's a way for oil/gas to drip out. It goes into a filter in the breather box and then looks like it drains out of the drain hose on the breather box.

Also, I grew up in Seattle and graduated from UW. The bike is from Seattle too.

Thanks for the help!
 

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I don't remember my 500T carb having a hose like that. I'd go look but I rode the nighthawk today.
 

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Discussion Starter #12
Here are 2 pics:
The first is the tube going into the breather box (pink circle)
The second is the tube coming out of the engine. (blue circle) IMG_6635.jpg IMG_6636.jpg
 

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Here are 2 pics:
The first is the tube going into the breather box (pink circle)
The second is the tube coming out of the engine. (blue circle) View attachment 249010 View attachment 249018
When you said "small tubes that leave the carb and enter the box?" that threw me off. That tube is for crankase ventilation. I wouldn't plug it but not sure what to do with it.
 

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Discussion Starter #14
When you said "small tubes that leave the carb and enter the box?" that threw me off. That tube is for crankase ventilation. I wouldn't plug it but not sure what to do with it.
Yea sorry i was going off memory when I wrote that. The few comments I have seen from people were that it spews some fluid out. One recommendation was to tie it vertically so it doesn't spill out everywhere. My current thought is to tie it facing down so that if it does spew it heads toward the pavement. Maybe put some foam in the tube itself to help filter it.
 

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When you said "small tubes that leave the carb and enter the box?" that threw me off. That tube is for crankase ventilation. I wouldn't plug it but not sure what to do with it.
Thats right. It's the breather tube of the engine. Honda changed the breather tube design from a simple hose (450) to a hose connected to the air box with the 500. Probably because of the assumption that the cleanest air is in the airbox.
500 breather.jpg
I wouldn't remove the airbox just for the looks. If you want to use pod filters you can try the angled pod filters from Common Motor Collective witch sould fit in the exising airbox.

Honda CB350 / CB360 / CB450 Angled Boot Pod Air Filters | Common Motor Collective
 

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Discussion Starter #16
Thats right. It's the breather tube of the engine. Honda changed the breather tube design from a simple hose (450) to a hose connected to the air box with the 500. Probably because of the assumption that the cleanest air is in the airbox.
View attachment 249042
I wouldn't remove the airbox just for the looks. If you want to use pod filters you can try the angled pod filters from Common Motor Collective witch sould fit in the exising airbox.

Honda CB350 / CB360 / CB450 Angled Boot Pod Air Filters | Common Motor Collective
Cool thanks for that link!
 

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According to the manual.. that tube and breather box is for increase fuel efficiency. The leftover fuel in the air is supposed to be reburnt a second time to help meet USA's standards

Just repeating what I read in the manual
 

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According to the manual.. that tube and breather box is for increase fuel efficiency. The leftover fuel in the air is supposed to be reburnt a second time to help meet USA's standards

Just repeating what I read in the manual
Yeah, I know. I’ve read it as well but I doubt that you could possibly measure any increase in fuel efficiency. It sounds more like marketing talk about efficiency to me although it makes sense to me to end the breather in the air box.
 

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It is a sort of pollution control just like a car had a PCV valve from back in the day. The idea is the vapour inside the engine that is generated by the combustion process such as blow by on the rings for instance is vented out that tube on the valve cover and recycled back into the air box and then back into the carb venturi to be reburned.
The simplest thing is to vent it to atmosphere and extend that tube down to the lower section of the frame where it can drip any vapour that condenses back down on the road.
 
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