Racers thread mainly, having trouble with your breathing ?

Ron, No relation that I know of, but as the world knows all with the Dietz name share a superior intellect. There is a Carol in the family but she was a Williams imported from the UK.
 
So what has happened with this? Has the original design been modified? Did they work? Are they for sale?
Its shiny and i want one!

FFFANARCHY
 
dual breather is not for sale, did not work, seems the balls decided to fight each other or they got confused and let way too much oil through

on our black engine race bike I machined up a custom reed valve body that bolts on to where the starter motor should be as we don't use starters anymore on the race bikes
just use a remote crankshaft starter as don't like rollers
reed valve seems to be working far better and the standard set up is still in place, we just removed one of the outlets and made the standard deal out of billet
 
If any Lav motor should have major venting dramas, it's the 360 deg SFs, both slugs sucking and blowing in unison. Early (SF1 and prior) had a smaller breather port on the cam cover, so in making the dia bigger the fabbrica must have known it was an issue. I'm hoping that running a 270 crank reduces the fluctuations somewhat but would be interested in an upgrade for the 880 I'm building if it's doable without major hassle.

Not an expert in this, so any advice happily taken on board. Phil, what is the symptom of insufficient venting on a big SF twin? I have blown the gearbox countershaft seal completely out of the motor after a high speed run on very worn rings with the old SF1 small breather!! Oil everywhere ... is this an extreme example of the potential probs?
 
Hi Quentin - The main manifestation is the g'box oil seal blowing. the unseen ones are extra extra pressure under the pistons sapping power and adding stress. I've added an extra breather over the g/box on the twins - with a Morini 3? breather baffle in it . Have got a Chinese reed valve block for some 50cc motor that looks easy to fit on the hollow L/H rear engine mounting block - will do this for my 860cc.
    When we made our 120? 1200cc motor in 1980 - on testing at Snetterton we found that we were continually breaking the 6mm cambox bolts. I remembered my old factory endurance triple had steel horseshoes over modified cam pillars - with an 8mm nut bronzed onto them and the cambox was beefed up with weld to take 8mm allen screws. didn't want to do something like that as it only masked the problem - so we put an extra (quite large) breather from the cambox. This solved the problem.
  Haven't got the brainpower to work out  if one breather blowing and one sucking is correct - but with breathers top and bottom it has always worked - am minded these days to use one way valves to be sure! - regards -Phil
 

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Piranha Brother 2 said:
If any Lav motor should have major venting dramas, it's the 360 deg SFs, both slugs sucking and blowing in unison. Early (SF1 and prior) had a smaller breather port on the cam cover, so in making the dia bigger the fabbrica must have known it was an issue. I'm hoping that running a 270 crank reduces the fluctuations somewhat but would be interested in an upgrade for the 880 I'm building if it's doable without major hassle.

Not an expert in this, so any advice happily taken on board. Phil, what is the symptom of insufficient venting on a big SF twin? I have blown the gearbox countershaft seal completely out of the motor after a high speed run on very worn rings with the old SF1 small breather!! Oil everywhere ... is this an extreme example of the potential probs?
Click to expand...

Reckon the breather is quite adaquate for road use, factory racers often had an additional breather from the oil filler hole.

I found an additional breather allowed my long-stroke GTL to rev a bit free-er, the breather system seems to be at its limits with 750cc.

Seems breather issues begin once when excessive piston blow-by sets in. 

The larger breather requires the later head/rocker cover to be fitted, has a larger spigot for the bigger thread.  Should be enough of those laying around.

piet
 
Thanks Piet and Phil. I've got the big breather cam cover already. Wolfgang sells small breather versions that have been bored and fitted with the larger thread/cap. I like the idea of using the cavity at the rear engine mount 0 but I guess the oil filler would serve as well without mods.

Better get off this laptop and head to Phillip Island to watch the boyz in practice and qualifying!!
 
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