crankcase breather, where the f is it?

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Neosophist
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Re: crankcase breather, where the f is it?

Post by Neosophist » Tue Jun 21, 2011 2:57 pm

porndoguk wrote:
vfrderek wrote:Didnt you fit a pipercross filter or summat Rick?
yeah i had 2 spare piperX filters i had from an old car, i gave the other to curt,

doesnt make any noticible difference but i guess in theory it should help, and maybe lower emissions! after all only clean air is going into the induction and not dirty oil vapour,
Thats not quite true.

The crankcase has a breather (like all engines do) as the pressure of the combustion often leads to minor 'blow by' where in minor amounts (or major if you have knackered rings / cylidners) of the air/fuel mix burnt get past the piston rings and into the crank-case.

If the crankcase was sealed this pressure would send the gas along with some oil out through the weakest point, probably a joint / gasket or an oil seal somewhere.

Anyhow... some of these gasses are only partly combusted when they enter the crank-case, also water from condensation and unburned fuel gets into the engine oil.. when this oil is upto tempurature these 'burn off' (they evapourate)

Venting these out to the atmosphere was common on older cars as they didn't care too much.

Modern vehicles vent the crankcase back through the inlet, it's only a tiny fraction of the actual air/mix that is reused per given stroke but this helps to burn off any unburned fuelvapour thats come from the crank-case, and giving cleaner overall emissions.

There are cases when running high turbo pressure that the crank-case breather no longer works properly which is why some people vent them to atmosphere but theres no real reason to do so... it's not like your running the bike on 100% oxygen...
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

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Re: crankcase breather, where the f is it?

Post by Neosophist » Tue Jun 21, 2011 2:58 pm

porndoguk wrote:
Neosophist wrote:
hunter wrote:I hope not to,But that's the norm.
Indeed... is it whitesmoking constantly / a lot?

What does the oil look like, have you took the rad-cap off and have a look in there, whats the water look like, any oily droplets? are you loosing water?

Could just be a lot of condensation in the air.. these bikes take a while to warm up fully.

Ditch the oil and coolant and refil from scratch and keep an eye on them.

And it'd be worrying if its the h/g... these bikes are uber reliable even when seriously abused / neglected.. after years on 400 forums i've never seen anyone change vfr head-gaskets
im changing mine next month :P

to accomodate for the tidier heads i have from geoff.
Tidier heads? can't you clean yours up.. seems like a bad idea to me :whistle:
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

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Re: crankcase breather, where the f is it?

Post by porndoguk » Tue Jun 21, 2011 3:05 pm

i have snapped studs, some muppet has drilled a m8 thread on the rear there in a bit of a state,
and i dont want to be fitting a nice new tyga exhaust and then having no stud on the front and haveing to drill a bmm hole in one of the rear clamps,

perfectionist i know, but ill also get the valve clearances spot on too :)

i need to work out where i can get cheaper valve stem seals & gaskets

coming out at £6.50+vat each! and i obs need 16 of them!
and gaskets at £30+ each, i may get the set on ebay, but not sure of there credibilty, id always go for honda but i dunno on this occasion.

they any cheaper out there in japan land mart?
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Re: crankcase breather, where the f is it?

Post by oldgreyandslow » Wed Jun 22, 2011 10:09 am

Quick update

No water in the oil and no oil in the water, the plugs were very oily, I'm changing them, doing the valve clearances and cleaning/checking tne carb jets etc, replacing the air filter and putting it all back together and hoping!

If there's no smoke I'll be happy, if there is I'll do a compression test. And depending upon the result of that cry in the corner of my garage

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Re: crankcase breather, where the f is it?

Post by Neosophist » Wed Jun 22, 2011 11:26 am

That smoke could be fuel.. especially if its' running so rich! wipe your hands aroudn the exhaust and see how much soot there is..

will be loads better with the carbs sorted.

Hopefully it's not burning oil >.<

And yep.. Rick doing the job proeprly is expensive.. cost me quite a lot to do the Kawasaki (head / base gaskets are cheap though for genuine Kwak ones.. about 25 quid for both), valve stem seals, cam chain, camchain tensioner are not so cheap!

(I lapped all the valves in as there was some blowby due to rusty valves from standing a while...)

Hence me recomending not removing it unless necessary!!

Can you not remove the stud?
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

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Re: crankcase breather, where the f is it?

Post by porndoguk » Wed Jun 22, 2011 11:31 am

Neosophist wrote:That smoke could be fuel.. especially if its' running so rich! wipe your hands aroudn the exhaust and see how much soot there is..

will be loads better with the carbs sorted.

Hopefully it's not burning oil >.<

And yep.. Rick doing the job proeprly is expensive.. cost me quite a lot to do the Kawasaki (head / base gaskets are cheap though for genuine Kwak ones.. about 25 quid for both), valve stem seals, cam chain, camchain tensioner are not so cheap!

(I lapped all the valves in as there was some blowby due to rusty valves from standing a while...)

Hence me recomending not removing it unless necessary!!

Can you not remove the stud?
the front stuff is snapped deep in the head, so would require drilling and tapping,the rear has been drilled to an m8, so i dont want to be drilling new tyga exhaust to accomadate the changes, so im fitting the refreshed heads that have 8 mint m6 threads, which ive run my tap down all the threads to clean etc, all will be copper greased.

lap the valve,

valves clearanced set to tollerance,

new valve seals

new head gaskets,

all carbon removed from the outlets that is all i is doing :mrgreen:
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Re: crankcase breather, where the f is it?

Post by oldgreyandslow » Wed Jun 22, 2011 3:29 pm

Neosophist wrote:That smoke could be fuel.. especially if its' running so rich! wipe your hands aroudn the exhaust and see how much soot there is..

will be loads better with the carbs sorted.

Hopefully it's not burning oil >.<
There's an awful lot of soot!

I'll get there eventually! Or die in the attempt

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Re: crankcase breather, where the f is it?

Post by Neosophist » Thu Jun 23, 2011 12:25 pm

Yeah sounds like it's been running far too rich (which will explain the crap mpg too) get the carbs checked / reset and you'll be fine :-)
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

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