Breather pipes and rev counter

[Ralph]

The electronic rev counter behaves fine till about 5500 rpm then takes off into the red
going to check all the connections but wonder if it's a known fault.
The small breather pipes on the heads, were do they go? on mine they
join at a T piece then a pipe goes down to a connection on the small
front bit of the chain guard just above the sprocket, it looks a bit Heath
Robinson so suspect it's not as original.

[George 350]

Hi Ralph,

After many years, my rev counter began to do almost the same as yours, except mine did it from 6000rpm. Having tried a new wiring loom and taking the signal from the 'other' cylinders coil unit without any effect, I decided to live with it. Then I had to replace the voltage control unit (now has an NLM one) and lo and behold, the rev counter behaves perfectly!

Regarding the breather hoses, it depends on what model you have:- early bikes were a simple road draught system, where each rocker box pipe went via a 7mm bore pipe to just below crankcase level (front fixed to front downtube, rear went down the gap between chassis number plate and the back of the engine) while later bikes had a system which connected the rocker boxes to the airbox. I don't recall ever seeing one which went onto the sprocket cover though. Post a picture and others might comment as to what you have.

George.

[Ralph]

Thanks for that George.
It's a 75 Strada, I think your right about the breather I think the first owner had decided to
put any oil coming from the breather to good use to oil the chain but it never blow's any out
so it does not make any difference, the plastic pipe used is getting due for replacement so
I was thinking of returning it to standard, I also wondered if the configuration had any
impact on the valve gear oiling as I have come across breathers of tuned length but it
does not seem so, not seen any connections to the air filter so straight pipes it is.

What you say about the rev counter is interesting as I fitted a NLM regulator a bit back
and have only noticed the problem since then so mine seems to be acting the opposite
to yours but I will look into that, the NLM reg run's very slightly lower volts than the org
one but seems to work fine will have a look at that side of things.

Thanks again will let you know how I get on.

[EVguru]

I also wondered if the configuration had any
impact on the valve gear oiling as I have come across breathers of tuned length but it
does not seem so.

You need to make sure that both labyrinth baffles are present in the main crankcase breather. They create just enough pressure to direct the oil mist to the top ends.

[Ralph]

Yes the main breather is as intended it was just the two top ones from the rocker covers,
after looking at the rev counter connections though I could not see any problem all being
clean and tight it now works better not perfect but it does not take off till over 7000 now
and I can live with that till winter then I will have another look.

[adrian]

i've looked closely at the crankcase breather on my Strada, and the way the baffles are orientated, it looks the passage of air is blocked where the 2 baffles meet. When running the engine, there doesn't seem to be any air flow from the breather, and a thumb held over the end generates no back pressure. Should i cut back the plastic hose and destroy the second baffle to make a clear passage (a baffle will never come whole as the hose has shrunk around it).

[Ralph]

I would not, on mine the main breather as a very slight pulsing if you cover the end of the pipe
with your thumb but you have to take care to get it fully covered, dont mess with it unless you
are sure something is up as it plays a big part in oiling the rockers and shafts.

[EVguru]

If you ever need to get a baffle out, just split the pipe along its length and unwrap it.

If the pipe is very hard then use heat to soften it. Boiling water is the safest way.