Cam Breather Pipe Re-positioning



27 replies to this topic
  • David_W

Posted October 27, 2003 - 01:04 PM

#1

Hi All

Long time since I visited TT. Hope everyone is good.

Has anyone re-positioned the breather pipe from the top of the engine that exits at the bottom below the engine guard? It's always bothered me, and with all the rain and water we get in the UK, I'm worried it is going to suck water up one day.

Any ideas? I had thought of routing it into the airbox, or up behind the headlight? :)

Thanks.

David

  • simon@vic

Posted October 27, 2003 - 01:38 PM

#2

it shouldnt ever suck when the motor is running or not. possative crank case pressure.

  • Dean400

Posted October 27, 2003 - 02:00 PM

#3

When the piston travels up, it is going to suck air; and when the piston travels down, it is going to blow air; right?

  • tctrailrider

Posted October 27, 2003 - 02:09 PM

#4

Has anyone re-positioned the breather pipe from the top of the engine that exits at the bottom below the engine guard?


Yes. Try the search option for info.. If you stall it while the hose is under water it sucks whatever up the tube. I beleive the solution was to install a T up high, leaving the current drain and rerouting the other into the air box.

  • simon@vic

Posted October 27, 2003 - 05:00 PM

#5


I beleive the solution was to install a T up high, leaving the current drain and rerouting the other into the air box.


yes
this is what i and most others do

  • yamahasocal450

Posted October 27, 2003 - 06:59 PM

#6

i just took an aircompressor hose fixer thingy majigger and screwed it into the airbox and plugged it up and secured it with a zip tie :)

  • David_W

Posted October 28, 2003 - 12:27 AM

#7

Cool. Thanks for the tips guys.

Cheers.

  • Quickrik

Posted October 28, 2003 - 03:00 AM

#8

Best tip I've got is re-route it down the left side of the cylinder so that it dribbles the excess oil onto you chain. Hold it in place by a bit of lockwire or cable tie by the cam chain tensioner.

  • MN_Kevin

Posted October 28, 2003 - 04:11 AM

#9

it shouldnt ever suck when the motor is running or not. possitive crank case pressure.


:) THIS IS ABSOLUTELY INCORRECT! :D

The engine WILL suck while you are kicking her over. It pulsates in and out while running >> the pulse "out" exceeds the pulse "in" >> you shouldn't (key workd SHOULDN'T) >> suck anything in while the engine is running.

NEVER, EVER, EVER fire off your bike if the breather tube is submerged in water, silt, sand, pumice (that WOULD be bad!! :D).

Your engine WILL gulp in whatever is at the end of that breather.

After having my breather up behind the headlight, I have installed a 'T' as the line exits the head. One end hangs down along the main frame as OEM. The other end of the 'T' goes up into the airbox.

This allows the condensing oil vapor to drain out of the tube, vice just collecting in it or draining back into the engine...

  • Hick

Posted October 28, 2003 - 09:31 AM

#10

I had thought of routing it into the airbox, or up behind the headlight?


Not sure about your bike, but on the WR/YZ 426 it looks like they planned for an eventual breather routing to the air boot. On top of the air boot there is a nipple where you could make a hole and install a hose barb (you might need a 90°). Then Tee off of that either in the stock location or down by the carb vents. I never tried that (live in the dez) but that would make for the cleanest install IMO.


Hope this helps.

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  • AfricaOffroad

Posted October 28, 2003 - 11:05 AM

#11

I've started my 450 a number of times while partly submerged in water.

When draining my oil (do it every 200 miles)I have never picked up any water contamination.

I find it hard to believe that Yamaha would make so basic a design fault on their enduro bikes :)

Posted Image

  • Hick

Posted October 28, 2003 - 11:37 AM

#12

I find it hard to believe that Yamaha would make so basic a design fault on their enduro bikes





That's pretty funny. :)


Put your finger over the end of the breather tube and kick her over a few times. At some point you will feel a slight amount of vacuum.

  • JerseyDirt

Posted October 28, 2003 - 12:08 PM

#13

Whats the point of putting a "T" in and routing the hose to two places as opposed to just routing the hose directly and only to the airbox?

  • tctrailrider

Posted October 28, 2003 - 01:29 PM

#14

Whats the point of putting a "T" in and routing the hose to two places as opposed to just routing the hose directly and only to the airbox?

The thought is by using a T the "blow by" will drain through the lower tube rather than into the air box. If a vacuum is created it will suck air from the air box before it lifts the weight of the water through the lower tube.

  • Dean400

Posted October 28, 2003 - 01:31 PM

#15

Does the 450 have the breather in the same location as the 400/426?

Anyway, I can say that my WR400 will suck water when starting it with the breather submerged. I stalled it while crossing a creek and hopping over a log. :)

  • JerseyDirt

Posted October 28, 2003 - 01:45 PM

#16

When you say the "blow by" will drain through the lower tube do you mean the small amout of oil which escapes? If so, then is the point of dual routing the hose just to help keep the airbox cleaner?

  • MN_Kevin

Posted October 28, 2003 - 02:11 PM

#17

Whats the point of putting a "T" in and routing the hose to two places as opposed to just routing the hose directly and only to the airbox?


This allows the condensing oil vapor to drain out of the tube, vice just collecting in it or draining back into the engine...




If so, then is the point of dual routing the hose just to help keep the airbox cleaner?




The thought is by using a T the "blow by" will drain through the lower tube rather than into the air box. If a vacuum is created it will suck air from the air box before it lifts the weight of the water through the lower tube.




the answers were there, before your questions were even asked.

  • dominator426

Posted October 28, 2003 - 05:17 PM

#18

How about installing a PCV valve, about halfway down the tube and positioning it so pressure can escape normally, and seal up under negative pressure...

  • Hick

Posted October 28, 2003 - 05:59 PM

#19

How about installing a PCV valve, about halfway down the tube and positioning it so pressure can escape normally, and seal up under negative pressure...


Not sure if that will allow the cases to vent properly since it is a one-way valve. But I think it has been done before all the same.

  • MN_Kevin

Posted October 28, 2003 - 07:40 PM

#20

a PCV valve is known as a check valve.

Never having taken one apart, I do not know what they look like inside. There are hang open checks and spring loaded checks. Some check valves require a certain position to operate, i.e. completely horizontal.




 
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