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this oil in airbox drain pipe is happenin with not just yamaha but alot of the newer models from all makes

Quote:

Originally Posted by johnno (Post 99380)

this oil in airbox drain pipe is happenin with not just yamaha but alot of the newer models from all makes

I got my breather box replaced on Friday at the same time as getting an oil change. Dealer did it under warranty and total time for both jobs was about 30 minutes. I'd given him the deails on the part numbers and he'd been able to sort the rest from there. Interesting he'd previously spoken to Yamaha about the problem and they'd not mentioned this at all to him!

Would agree this is not an easy job. Mechanic at the dealer was having problem with it as it's in a difficult to access area.

Will have to give it a few days and see if i'm getting any oil collecting anymore.

I've done about 2500km's since the new breather was installed and indeed, no more oil-residu in the drain-pipe! And during those km's I was runnin' high revs a lot(on motorways, doin' 130kmh-5000rpm), which used to fill the pipe easily! But ya might ask, where is the oil-residu now? Will it be filtered and returned to the oil tank, or straight back to the engine? What does the new breather do exactly, which the old one didn't? I think we need answers to these questions, don't ya agree?
Greetz, Hans.

Nerd Alert, Nerd Alert!

Quote:

Originally Posted by dallas (Post 99826)

Hi Hanz - good to hear the mod works - I've got the part on order with my dealer too...

Basically the plastic box is a catch tank - the crankcase breathes into this, along with any oil that is blown out under pressure (as you surmise, this tends to happen at higher constant revs - ie motorway riding). The idea of the tank is that it collects the oil and allows it to drain back into the crankcase. There is another pipe that leads from the catch tank to the airbox which allows the pressurised air to flow out of the catch tank and into the airbox, where it is re-burnt in the engine.

The problem (it seems) with the original design is that the pressure of the air/oil mix from the crankcase was too great to catch it all in the tank, and therefore more of the oil passed though the second hose and into the airbox.

The re-design includes baffles (plates, like a maze) inside the catch tank so that the oil hits these and separates from the air-flow - the air continuing on out into the airbox, the oil reforming and returning to the crankcase down the pipe it came up - typically once the revs drop and the crankcase pressure recedes...

How boring am I?!

xxx

Thanx, JMo! That's cleared now, good explantion. And you're not boring....you're experienced, well-informed, enterprising, funny, sharp, good rider etc., but not boring!! Thanx again, greetz, Hans.

One note between, the MT-03 uses the same (old design) plastic tank. Interesting to know that I did not hear about problems of these MT guys. On the other hand, some are complaining about surging.

At the end we can be happy that our big single runs that smooth, without surging and now with an 'evo' plastic tank. Hope that in other countries the exchange will be done as trouble-free as in Germany (also some dealers need a customer's hint to read their Yamaha-announcements).

Gruss
hombacher

Quote:

Originally Posted by JMo (Post 99832)

Not so true, the oil pressure on a dry sump motor is about 20 psi or 1.5 bars, actually a very low preassure, but when the temperature gets higher, the AIR PRESSURE inside the crancase gets higher and must be released, this is the main reason for the breather, but along with the air some vaporized oil goes away with the air, the main purpose of the catch can is to cool down and depressure that air so the oil can became liquid again and come back to the crankcase, the remaining of the vaporised oil goes tru the intake and gets burned into the engine.

The design problem on the XTZ is that the breather box is not able to cool down the vapors long enough to make the oil come back to the crankcase, but the long hose from the breather to the air intake IS LONG ENOUGH to cool it down, and the oil goes down to the drain pipe iso being burned inside the engine.

The new breather box has a longer path and is able to cool down the excess air and vapours before in reaches the airbox.

Excuse my poor english, i'm spanish,

have fun,

j.

Ah - another nerd! Thanks for clarifying that Jiauka - I should have been more clear that it is the air pressure inside the crankcase that needs to be released, rather than the oil itself under pressure - and as you say, some oil is carried out along with the air...

xxx

Quote:

Originally Posted by JMo (Post 99852)

You're wellcome, from your previous post it looked like you were talking about OIL pressure, and some people may think that the full crankcase, head and so is under oil pressure, and we all should know that this is not true, the actual oil pressure is quite low, but the air pressure needs to be released.

BTW: I have changed the breather too, so far so good ;) :), no more oil at the drain hose.

And some side note, when an engine gets older and the piston rings have some leakage the pressure from the top of the piston at the compression and power stroke goes tru the rings and increases the air crankcase pressure a lot, but when the exhaust valves open that pressure is released back tru the rings to the combustion chamber but that air has some oil vapours, the engine "burns oil", a good breather box design minimize that issue.

have fun,

j.