Topic: Can anyone identify this for me?

[750K8 Kev]

I just bought my 78 750k last week and noticed this hose with a clamped nipple coming of the carb. It looks like a vaccum hose, but I'm scratching my head as to why it would have a clamp and male end. I can't for the life of me find where it would go, anyone have an idea? It's coming off the left side of carb 2, and mounted off a vertical nipple.

Thanks,
Kevin

[Nikkisixx]

It is most likely the vent tube for the float bowls.  It should be tucked away where dirt and whatnot can't get into it.

[750K8 Kev]

It is most likely the vent tube for the float bowls.  It should be tucked away where dirt and whatnot can't get into it.

but why the clamp and plastic insert on the end?

[754]

 A 78 has a  elbow fitting on top of airbox.. pretty sure that hose is breather off the valve cover and should go to air cleaner..

 77/78 emission stuff..

[750K8 Kev]

Thanks guys

[madmtnmotors]

The male fitting connects to another hose that runs over the air filter housing on my 78' CB750K. There is even a small loop bracket on top of the air cleaner to hold the vent hose in place. From there the additional hose routes down behind the engine in the vicinity of the carb drain hoses (I think). I think they split the hose at the top of the air filter housing to maybe allow removal of the air filter housing without pulling the vent tube from the carb since it might be tough to get to.

[750K8 Kev]

The male fitting connects to another hose that runs over the air filter housing on my 78' CB750K. There is even a small loop bracket on top of the air cleaner to hold the vent hose in place. From there the additional hose routes down behind the engine in the vicinity of the carb drain hoses (I think). I think they split the hose at the top of the air filter housing to maybe allow removal of the air filter housing without pulling the vent tube from the carb since it might be tough to get to.

So it's nothing to worry about then?

[Spanner 1]

I think I'd move/extend it like mad... describes, you need it clear and clean as it is a vent line for the carbs.....

[TwoTired]

If it attaches to the second smaller nipple on top of the carbs, it is a carb bowl vent.  It allows air in to push the fuel through the jets.  It should not be plugged.  But, it is best if it is long so as not to allow dust in, and bugs die of fuel vapor before they can crawl into the carb bowls.  The union is to make servicing easier, I believe.  It should have an extention hose that routes back between back of engine case and swing arm pivot.

[fishhead]

If you do unplug it, make sure that you don't have a vacuum source at it.
  Some of the Keihin PD carbs also had a vacuum source for the vacuum operated petcocks(and I believe the Automatics also had a vacuum source for something there also).

[eurban]

Holy smokes, there is a lot crazy of speculation here! ! !

Simply put that is the carb vent hose and just about every newbie to the 77/78 PD carbed bikes wonder where it should be connected to.  The answer is that it doesn't connect to anything and while honda may have engineered some sort of clip to hold the hose out of harms way, letting it dangle about shouldn't cause any issues. The "plug" in the end is hollow and may serve to keep the hose end from collapsing or perhaps acts as a restrictor. . . .Fishead, there is no vacuum operated petcock setup on any SOHC 750.  The only Sohc that I have seen one with is the CV carbed 650s and this was an inline device mounted to the carb rack.  

[750K8 Kev]

 :DWell thanks for the responses everyone. I'll just extend it so it's outta the way and that's that.