[Drew71]

At some point in my motors life it got what looks like a reed poked into the front rocker. It does breath cuz oil mists up on my frame. But I still have rocker leaks.

That thing is prettier than girl with all her own teeth.

nice work mate

 

[kbg]

I think I'd be more worried about the poor top end oil feed on pre units
before the breathing!

 

[bon]

You're right kbg , but having what little oil there is up there to leak out doesn't help either.

 

[nomad69]

Here's a couple!!

 

[reverb]

...KBG, I have an old pre unit and have plenty of oil in the top end
the problem with the old ones is with the leaks; imposible to stop them, normally on external oil pipes.

 

[kbg]

...KBG, I have an old pre unit and have plenty of oil in the top end
the problem with the old ones is with the leaks; imposible to stop them, normally on external oil pipes.

Thats opposite to me, I got no leaks but very little oil gets up there!
If you stone all the banjos flat and anneal the copper washers, and
use the black rocker gaskets with the metal in the middle yours
should'nt leak either.
If everything is flat that is.
How do you get plenty of oil up there, do you run a feed from the timing cover?
I have a 3/32 restriction and get 10 psi cold and so low you can,t read it hot.

 

[reverb]

...hello Kbg, I do not know that black rocker gasket with metal!, however, I do not have any leaks in the rocker boxes bases.
The leaks are from the banjos.
I used the copper washers, but not anneal them, but with cement glue, do not worked for me.
Now I put aluminnum washers without glue (because they are so slim)
still I have leaks, too much I tell ya, but this is a 1948 engine...
Every time that I rebuilt something, the leaks seem to "change" the place, but always from one of the banjos

-possibly your problem is with the oil pump; mine working perfect; I rebuilt it few years ago

 

[lowbrowcustoms]

On my '55 generator pre unit Triumph race bike I have an iron head w/ eternal oil pipes. It doesn't leak at all. Wes (Four Aces) built the motor, just copper gaskets, I have had it apart a couple times, back together with same washers and no issues with leaks. I do have each rocker box vented. And yes, there is pressure there, run the bike with vented rocker caps and it is a steady and forceful exertion through each vent. I did not run a generator so made a block off plate and also vented from the crankcase additionally.

Tyler

 

[Timecycles]

Like Lowbrow, my 39 Triumph salt racer is vented off both rocker boxes and from the case. No leaks from any of the usual places. I have the motor apart and there is no evidence of oil starvation. Cheers.

 

[reverb]

...hello fellas, so seems that the solution is only with those vents...because with stock conditions, the old ones always leak too much from those banjos.


Timecycles, do you have any close pictures of your engine with those vents?

thanks

 

[hogster]

if it isnt leaking oil look closely on the flywheel cover see if you can make out the letters h-o-n-d-a

 

[bon]

I am going to use the breather with the reed valve set from a yamaha xs650 as recommended by the guys on here , this is to create a small vaccum in the crank case , but if i have open vents from the rocker box caps the air will flow in through them and be drawn down into the crank case and be pumped out from the main breather so no vaccum, i was going to use small non-return valves as used in pneumatic systems on the rocker caps, any comments ?

 

[Timecycles]

Reverb - I will get a pic up for your but I simply drilled and tapped the valve adjustment covers and threaded in a hose fitting. For racing, I made a small round steel catch bottle out of some exhaust tubing, mounted it under the bike and attached hoses from the bottle to the vents. The bottle is the vented to a small round air filter. I welded a bung in the bottle for a drain plug. Pretty simple system.

 

[reverb]

...hello Timecycles, ok
yes, I prefer the covers because I do not want to unbolt the boxes, due to torque, etc

thanks

-what I do not understand why the factory did not do that in the following years? They changed lot of things...very strange that nobody complained about it

 

[Nanonevol]

New owner of a 67 Bonneville. My mind is boggled at all this breather talk and opinions and improvements! I don't actually see a crankcase breather on my new purchase. Can someone tell me where it would originate on a '67?

 

[supercrouton]

New owner of a 67 Bonneville. My mind is boggled at all this breather talk and opinions and improvements! I don't actually see a crankcase breather on my new purchase. Can someone tell me where it would originate on a '67?

The crank breather on a '67 should be through the intake cam, and out of a tube "spike", facing toward the ground, in front of the countershaft sprocket.