Cylinder head cover breather removal

[ocmr2002-11]

Dear all,

A question.

I am fitting a GSXR1100WP engine (water cooled model, 1993 year) to
my Phoenix.

The bonnet won't close by maybe and inch to give you the scale of the
problem, it will close but only with some force (maybe 10kg weight).
The bonnet that I have has some history, but basically I can take a
few mm out of it (thinning), but I don't really (rather than really
don't) want to redo it (i.e. cut another hole) as it looks nice at
the moment and in my mind it is "finished".

I can't lower or rotate the engine, as it is in the right place and
the sump would be too low, and the exhaust angles would all go wrong
(given the top tube). Also the craddle is all made and working.


The clash is on the "cylinder head cover breather", which is a big
old aluminium block that basically contains a labyrinth of passages
intended to allow the oil out of the air before the air leaves the
engine (to the carbs, or to be vented in my case). This unit is about
25mm in height and would normally sit under the fuel tank (on the
bike). http://alpha-sports.com/supr/1993%20GSXR1100/18.htm 
So,
Can I take off this breather, plate it, and then use a cam-chain
breather (basically a breather that attaches to the oil filler hole).
That would buy me the distance that I need. I don't know much about
bike engines, but the 'busa doesn't have a breather on the cylinder
head cover (it has a crankshaft one), which is basically what I will
have.

At the moment I have rashly purchased a breather from an earlier
model of bike (GSXR750, which is slimmer and MAY have the same bolt
spacing), but I suspect it might not fit, or will not gain me the
required space.


I think that I have my thoughts straight on this, but any wisdom
would be appreciated.

Thanks,


Matt

p.s. no, I don't have a dry sump (in that case I agree the problem
goes away).


 
 
 

[Mike A Veal-175]

Matt,

You're unlikely to find anyone else running that particular Gixxer
(it's pretty old - but a good bullet proof choice), so in the absence
of any specific wisdom on that engine...

An oil breather is an oil breather is an oil breather.

Most bikes have crankcase breathers that feed into the airbox. In car
installations it is common to junk the airbox and fit a filter,venting
the breather to the atmosphere.

In your case, I'd suggest either a remote filter (on the end of a bit
of pipe), or a remote catch tank and filter. The catchtank is probably
the more cautious option - untill you know just how much oil is going
to come out of that hole!

Hope that helps.
Mike V.

[ocmr2002-11]

Mike,

Thanks for your reply and thoughts.

I wasn't expecting loads of replies, as I only know of a few of these
engines in cars.  Just from a practical perspective, they are pretty
powerful, pretty cheap, pretty strong, and doesn't need a cat (as it
is before the cut-off).  Also good history in sidecar racing, which
although different to cars is a pretty good indicator.


As you say, it was a sort of general question.  After the deafening
silence from this site I posted this on the suzuki forum (oldskool
suzuki) the response that I got said:

"
The internal breather passages are designed to work with either a top
or lower breather.
If you try to make a top designed breather work with only a lower
breather you can suffer oil hang up in the head as the crankcase
pressure stays in the crankcase which will cause all sorts of
problems the worst of which is blowing the motor to bits.
Are you running an airbox with the breather circuit still sealed or
is it venting to atmosphere, these engines were designed to run with
a closed CCV system so that the crankcase pressure runs at a negative
pressure under normal conditions, removing this system and also
changing to a low CCV system only IMO will cause problems.By all
means add a Gearbox vent if you are running without the sealed CCV
system, this will only help but may struggle to let the cases breath
sufficiently on its own.
"

It is difficult to know what confidence level to put on this, but it
sounds sort of credible.

Incidentally, if I can sort this problem then I won't need a bonnet
bulge on a Sylva Phoenix even with the standard airbox.

Matt

[moospeed-288]

I don't know how true this is;

> Are you running an airbox with the breather circuit still sealed
or
> is it venting to atmosphere, these engines were designed to run
with
> a closed CCV system so that the crankcase pressure runs at a
negative
> pressure under normal conditions, removing this system and also
> changing to a low CCV system only IMO will cause problems.

But if it is then I might have a solution to negative crankcase
pressure. A few years ago I bought in a batch of Krankvents (
http://www.et-performance.com/
 ) for the bike-engined group. Essentially it's a tough valve for
creating negative crankcase pressure, goes into the vent pipe.

It was hard to say what affect it had (compared with it's over-
inflated claims). It definitely changed the sound of the engine and
maybe felt like it revved up faster but at the same time I wouldn't
have said it improved torque as such.

I've got one which I only used for 100miles or so if you're
interested, I had it on the car but had to lengthen the breather
pipe as the old one was getting "sucked in" and was too tall. Also,
I wanted to turn it upside down so that any accumulated oil would
drain out. My brain might be failing but I think it was Jim Giblett
who had one (both of us with R1's) which got blocked up in it's
natural "vent updwards" situation. I just never got around to
putting it back on but was keeping it for a future project.

Like I said, I'm not 100% convinced about the product claims or the
statement in your forum reply below but you never know...might be
useful to you...

 - Steve
moospeed


--- In bike-engined-cars@..., "ocmr2002"
<matthew.robson@...> wrote:
>
> Mike,
>
> Thanks for your reply and thoughts.
>
> I wasn't expecting loads of replies, as I only know of a few of
these
> engines in cars.  Just from a practical perspective, they are
pretty
> powerful, pretty cheap, pretty strong, and doesn't need a cat (as
it
> is before the cut-off).  Also good history in sidecar racing,
which
> although different to cars is a pretty good indicator.
>
>
> As you say, it was a sort of general question.  After the
deafening
> silence from this site I posted this on the suzuki forum (oldskool
> suzuki) the response that I got said:
>
> "
> The internal breather passages are designed to work with either a
top
> or lower breather.
> If you try to make a top designed breather work with only a lower
> breather you can suffer oil hang up in the head as the crankcase
> pressure stays in the crankcase which will cause all sorts of
> problems the worst of which is blowing the motor to bits.
> Are you running an airbox with the breather circuit still sealed
or
> is it venting to atmosphere, these engines were designed to run
with
> a closed CCV system so that the crankcase pressure runs at a
negative
> pressure under normal conditions, removing this system and also
> changing to a low CCV system only IMO will cause problems.By all
> means add a Gearbox vent if you are running without the sealed CCV
> system, this will only help but may struggle to let the cases
breath
> sufficiently on its own.
> "
>
> It is difficult to know what confidence level to put on this, but
it
> sounds sort of credible.
>
> Incidentally, if I can sort this problem then I won't need a
bonnet
> bulge on a Sylva Phoenix even with the standard airbox.
>
> Matt
>

[ocmr2002-11]

Thanks Steve,

It seems to be one of those areas which doesn't have any well known  
formulae.  I guess the gentlemen of Honda/Suzuki/Yamaha/Kawasaki know
the answer.


The real answer will probably engine specific.  Based on the lack
of "I did this and my engine blew-up" evidence, I suspect as long as
the pressure doesn't build then most things are fine.


What I have ended up doing is getting a gsx600 breather, which is
much more slimline, and is a bolt on (slight fettle) replacement*.  
It doesn't have as big a hole as the original, but its pretty damned
similar.  It is from an earlier bike, and they did make the hole
bigger on the later one, but I will probably add a crankcase breather
to be safe (loads of space down there).

Most critically, the bonnet now shuts!

Thanks for your kind offer of this special valve.  It all sounds very
clever, but I think I will avoid further complications for the
moment.  The question I always have with these "wonder devices" is,
do the major manufacturers use it, and if not why not.


If I discover  anything further on this dark art, then I will let you
know.  I guess I could talk to TTS or AB, but it feels wrong to ask
for advice when I am not going to send them money in exchange.  Maybe
next time I am buying something from them I will ask.


Anyway and most importantly, "my bonnet shuts!".

Matt

*also a bit of trimming to the underside of the bonnet.  Angle
grinders are damned good.