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Help identifying hoses and what goes where CRF250X 2011

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Hi,

 

Just getting the bike ready for the season and found two oddities and can’t seem to find a solution myself so thought I’d ask.

 

There is a clear/reddish tube that is clipped onto the swing arm but when you follow it up mine does not seem to be connected. Not sure where it belongs;

 

IMG_0737.JPG

 

Then, the t-intersection coming off the valve cover only has two connectors. Did something fall off?

 

IMG_0738.JPG

 

I’ve just taken the smog kit off and blocked the things that needed blocking but I’m worried I missed something or messed it up.

 

Thanks!

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Posted (edited)

That is the crankcase breather,

 

a hose plugs into the back of the valve cover (near the top engine mount)

then splits into a T  (2nd pic)

one end off that T plugs into the airboot (nipple closest to the filter)

the other end is routed towards the bottom of the bike and has a plastic plug in the end (circled)

Hard to see but that lower tube may be missing a section, seems a bit short.

Edited by mlatour

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Posted (edited)

The smog pump also plugs into the airboot but to the nipple closest to the carburetor.

Edited by mlatour

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I think it will be able to route over, it just looks as though it was always in this position. I didn’t want to assume that both questions were the same issue.

If that’s the case though, I must have been sucking air in past the filter, possibly dirt too.

That’s not good!

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While it can suck in some air, I think the crankcase breather actually does more 'pushing out' of combustion blow-by.

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The  T connection in picture 2 connects to the tube on your swing arm if I recall correctly.

You can remove the 2 tubes and the T, plug the airbox hole it leaves (showed in picture 2), and completely remove the big tube from picture 1.

Run a new line from the valve cover to the swing arm where all your tubes are...makes it easier to work around the carb and cleans it all up, that's all your missing.

That's what my tokyo smog removal kit did.

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Posted (edited)

While most engine breathers run a single (unplugged) down tube,

Honda's theory in adding a T and splitting the line is to:

 

-not vent directly to atmosphere so no risk of ingesting dust or water

-create a vacuum inside the crankcase to reduce pumping losses but separating the oil mist in

the lower tube (plugged) so it doesn't get re-introduced in the fresh intake air stream.

 

On most CRF's the gearbox vent tube is also split by a T (seen on the far right in the 1st pic)

where excess oil can leak out the bottom and if ever it get clogged by mud, the top tube can still breathe.

 

IMO this engine & gearbox breather setup are best left in stock form as they are well thought out.

Submerging hot engine cases while crossing a stream will draw a vacuum/water from single lines simply routed downward.

 

 

Agreed that all the tubing on a CRF250X does add clutter on the bike.

I've removed the hot start cable, coolant overflow tank & hoses and, the PAIR smog valve but

pretty much left the stock carb and case breathers in stock configuration.

Edited by mlatour

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