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E: Engine Breather Timing a long description of a different way. (part 1)



Nigel Spaxman

Well Known and Active Website User
VOC Member
#21
At first I wrote this with the idea of MPH, but then I though why waste all that paper, I might as well just post it on here. I am glad you are all enjoying this. Maybe it will eventually be in MPH. I think it might reach a lot of other people by being in MPH. I would love to know what Neville Higgins thinks of this.
 

Nigel Spaxman

Well Known and Active Website User
VOC Member
#22
What I would love to see is a Vincent with a dry back tire after a 300 mile ride on a hot day.

They all seem to put a little oil on the tire.
My 1360 is promising, but I haven't done a 300 mile summer day with it yet.
On a long group ride some years ago a friend who was new to Vincents commented on this. " Every bike here has some oil on the back tire " was his comment.
There were about ten twins plus a Comet present.
I had a good look around and he was correct.

Maybe a catch bottle is the only way to eliminate this. A better breather will only add a bit more mist to the rear tire problem.



Glen
That's why a lot of people run a hose way out the back with a nozzle pointing outwards. On a perfect engine I think mist comes out of the breather pipe.
 

oexing

Well Known and Active Website User
VOC Member
#23
On a good engine there will be next to no oil mist from the breather - provided it is a one way reed or ball type. I will definitely fit a breather hose to the front or rear inlet valve cap with the reed valve at the highest place of the tube so any bit of oil collecting there will run back into the engine. With a one way valve there is very little air coming from the crank case.

Vic
 

vibrac

Well Known and Active Website User
VOC Member
#24
Do you realise that this subject has been talked about on the Forum for 10 years! if you don't believe me put "breather" in the search box top right
Not only that there are 50 years of MPH articles before that some suggesting altered timing of the valve.
It must be the most talked about subject in the VOC club, funny thing is its rarely mentioned on other makes
 

Glenliman

Well Known and Active Website User
VOC Member
#25
I don't think there is a breather hose termination (other than a catch bottle) that will prevent the mist from getting on the tire.
As mentioned, there were 11 Vincents that had just completed a good run and all had the dreaded moist back tire. Two or three might have had tired engines, but the others were all in good shape. I'm not sure if any had reed valve arrangements.

My OZ bike has the Eddie Stevens well back and curved out twin SS pipe breather termination. This is designed to eliminate the oil on tire problem.
The SS tubes and mount look very nice, but there is still a little oil mist getting on the tire.

When all of the leaks are plugged, this bike uses very little oil.
At the end of a 2500 mile trip to California it required just 8oz to bring the level back up.

Glen
 

oexing

Well Known and Active Website User
VOC Member
#26
Sorry, I should have been more specific: Timed breathers are quite OK as well when timed in a proper way. BUT: The original plus the elephant trunk get oil loaded air from the timing chest without much of a chance for the oil to separate from air. It is just not a brilliant place to fit a breather. So that is why I will pick the valve covers for adding a hose plus reed valve - and the reed valve at max distance from the cap so oil mist can settle and return into the engine. Works that way great on the 460 cc Horex that had a timed breather from the primary sprocket right vertical to the bottom - and a drop of oil regularly. So a reed valve went into the big valve cover in a box with ss wool as mist filter.

Vic
 
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Glenliman

Well Known and Active Website User
VOC Member
#27
Do you realise that this subject has been talked about on the Forum for 10 years! if you don't believe me put "breather" in the search box top right
Not only that there are 50 years of MPH articles before that some suggesting altered timing of the valve.
It must be the most talked about subject in the VOC club, funny thing is its rarely mentioned on other makes
That's because they are oily old buggers.
At the final Vincent Owners Club presentation for the IOM event in 2007 there were at least 150 Vincents parked on a rather nice flagstone patio area.
When it was over the flagstone looked as though the Exxon Valdez had gone aground there and split in two!
Still lots to talk about when it comes to Vincents and oil leaks.
Many have given up, some are still fighting the good fight!

Glen
 
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Glenliman

Well Known and Active Website User
VOC Member
#28
Just remembered that when John McDougall rebuilt the top ends on my OZ bike he worked his way into the timing chest as well.
Good thing, there were some issues at play in there.
One of the problems was with the breather.

I recall being quite thrilled with the bike first season as it did not drip condensate goop from the breather like all of the other Vincents. I took this as a sign that the engine was in great shape.
John found out why there wasn't anything coming out of the breather pipe.
The breather sleeve was seized on the spindle and the pinion was rotating on the sleeve!

Anyway, I see in the notes he provided which list labour performed each day"
"Opened up breather"
Now I recall discussion of this, but of course at the time I had no idea what he was talking about.
He definitely had his own ideas about breather timing and also modifying the breather for more open time.

Glen
 
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oexing

Well Known and Active Website User
VOC Member
#29
Yeah, another reason why I did not keep the original timed breather: The "alu bush" inside is not a real great bearing with its slot. Instead a needle bearing went in there and a reed valve will be connected to a valve cap.

Vic
 

Glenliman

Well Known and Active Website User
VOC Member
#30
On the other hand the replacement breather has done 55,000 miles without complaint
At least I think it's ok, haven't peeked inside there for 55,000 miles.
A few drops of grey goop still show up on shutdown, so I think we're ok:)
 


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