Author Topic: Timed breather, what is the actual timing?  (Read 2761 times)

Offline duTch

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Re: Timed breather, what is the actual timing?
« Reply #15 on: 18.03. 2016 09:47 »

Ok main breather's not blocked... *dunno*

Quote
If it's blocked, could it cause oil to build up in the crankcase?

  It's obviously there for a reason, so not being an expert just after dark on a friday eve *beer* I'd say it'd cause some kind of backpressure buildup  to add to the carnkcase pressure as the engine heats up *????*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Re: Timed breather, what is the actual timing?
« Reply #16 on: 19.03. 2016 12:04 »
Gappless rings cause a much greater induction pressure to be generated in the cylinder and will suck oil down the inlet valve .
You need to fit a seal to the inlet.
You also need to open the inlet a bit earlier.
I am a fan of gapless rings but they need a bit of fettleing to work properly.
Total Seal used to have a tech page which lists recommended things to do when fitting gapless rings to older engines.
They make a massive difference to the induction draught as well as increased cylinder compression.
I have them fitter to a couple of the hire cars and they produce a lot more down low but stick the boot in and I could empty the sump in no time flat.
This is exactly why I asked when was it blowing smoke.
Also you must specify the cast iron gappless otherwise you will e supplied the steel rings which are very difficult the bed in.
Because they ar gapless they produce excellent compression readings even if they have not bedded in properly.
Bike Beesa
Trevor

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Re: Timed breather, what is the actual timing?
« Reply #17 on: 19.03. 2016 21:04 »
Hi Trevor, I will ask Scott what specification rings he fitted, I know they were Total Seal brand, also that he has not fitted oil seals on the inlet (that would involve custom guides?) but then on the other hand his bike does not puff smoke particularly badly on the over run like you'd expect if oil was being sucked in through the guides.

If his problem is caused by blow by, which is as a result of fitting gap less rings, I think the easiest option would be to go back to conventional rings! What seems odd to me is that one does not hear of oil seals blowing out due to serious excessive case pressure problems on engines needing rebores, which implies the blow by on his bike is really bad, yet his bike is not smoking that badly.

On a recent long run to Dunedin (after a top end rebuild, new small ends, and light rehone) he thinks the crankshaft oil seal blew out after around 150 miles of 60mph cruising this limited him to 50/55 mph for the next few hundred miles or so, but after that the engine gradually improved until we were back up to 60 mph (oops officer) plus at the 1000 mile mark, so the theory is maybe the rings are very slowly bedding in. They have done a few thousand miles in total now.

So his current plan is to glue the seal back in and give the current set up another go, but he would still like to know if his breather timing is standard!

Going back to prior question, the oil tank breather has been checked and is not blocked.



New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Online KiwiGF

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Re: Timed breather, what is the actual timing?
« Reply #18 on: 20.03. 2016 07:38 »
The gap less rings spec is: brand Total Seal, gap less 2nd ring set, eg steel conventional top ring, gap less 2nd ring.


New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Online BSA_54A10

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Re: Timed breather, what is the actual timing?
« Reply #19 on: 20.03. 2016 09:57 »
Check that they are cast iron and not steel.
Total seal make a lot of steel rings and if you oreder by ring size and not engine type you can end up with wrong ring type.
The can aso be fitted upside down.
Bike Beesa
Trevor

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Re: Timed breather, what is the actual timing?
« Reply #20 on: 20.03. 2016 18:48 »
Hi Trev, As above he's definitely got a steel top ring (so potentially a bedding in problem there I think you said).

The spec of the other 2 rings is not yet known, but is cast iron even an available option from Total Seal for the gap less ring and oil ring? If so then he has potential bedding in problems there as well  *problem*

I'll check Scott is aware they fit one way up etc, I'm pretty sure he does know.
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Offline Rocket Racer

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Re: Timed breather, what is the actual timing?
« Reply #21 on: 20.03. 2016 21:58 »
Had a quick rummage, managed to find 4 breathers, gave them a quick clean with kero, and was slightly surprised that one (with a straight taper rather than a concave end) appears to have different timing *conf2*
Photo's attached.
I can't tell you what they came out of.
Didnt the longstroke motors have a completely different breather set up  *dunno*
If so then some motors do have different breather timing  *roll*
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline jachenbach

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Re: Timed breather, what is the actual timing?
« Reply #22 on: 21.03. 2016 02:45 »
So, Rocket's got a bunch of extra breathers. Not sure how many I've got (certainly more than I need). In the history of A10s has one ever worn out? Why are we saving these things????? Okay, I'm a packrat. Just can't bear to throw away any old part that MAY be needed someday. *smile*

Offline Rocket Racer

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Re: Timed breather, what is the actual timing?
« Reply #23 on: 21.03. 2016 03:12 »
So, Rocket's got a bunch of extra breathers. Not sure how many I've got (certainly more than I need). In the history of A10s has one ever worn out? Why are we saving these things????? Okay, I'm a packrat. Just can't bear to throw away any old part that MAY be needed someday. *smile*

Sadly those four are just the ones i found easily, there are more ..., as well as inner timing covers and other things no one will ever need  *whistle*
I  did wonder about making a bonzai tree from all the spare dynamo gears I've got  ;)
And I have a plan to build a "decorative" engine built up with mismatched and damaged parts either as a coffee table (sort of like the top gears porsche v8 one) or as a bar feature (if I had a bar   *beer*  )

Sorry, getting off topic
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Online KiwiGF

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Re: Timed breather, what is the actual timing?
« Reply #24 on: 21.03. 2016 07:31 »
If only I could mission controls permission for a coffee table like that....  *bash*

This link to a prior topic might explain the different breathers?

http://www.a7a10.net/forum/index.php?topic=9624.msg70144#msg70144

Scotts is a latish A10 swing arm, 1959 or 1960 from memory.
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Offline Rocket Racer

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Re: Timed breather, what is the actual timing?
« Reply #25 on: 22.03. 2016 06:58 »
a late type breathers gone in the post... Don't know if it'll arrive before easter but fingers crossed
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline duTch

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Re: Timed breather, what is the actual timing?
« Reply #26 on: 22.03. 2016 08:16 »

 Hey KiwiGF, unless I missed something, I guess we've all been just assuming that Scott has a BSA? maybe even an A10...? *smile*.

   If so, what model is it even, and I hope RR's breather helps.
 Maybe 'Scott' (or is he one of those imaginary friends *smile*) should join up? *beer*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online KiwiGF

  • Last had an A10 in 1976, in 2011 it was time for my 2nd one. It was the project from HELL (but I learned a lot....)
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New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Offline duTch

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Re: Timed breather, what is the actual timing?
« Reply #28 on: 22.03. 2016 11:11 »

 Ok,k, so the nudge gave results; great story, hopefully Scott and Jay will join in some time *smile*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online BSA_54A10

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Re: Timed breather, what is the actual timing?
« Reply #29 on: 24.03. 2016 10:03 »
We are getting a long way off topic here so I can 1/2 justify this speil.
Firstly the whole breathing thing and creating a partial vaccuum in the crankcase dates back to the era of oil slingers and felt seals.
No one bothered about it so no one actually thought about why we are doing it, they just did, and they did it wrong.

Air has a mass therefore there is a resistance to being moved and this applies just the same to flow through carburettors & valves as it does to crankcase venting.
Those who follow racing blue smokers will remember the massive leap in power that was attained when variable induction porting was introduced.
Those of you who play around with cam timing will also know that if it is right at idle it will be way out at 7000 rpm and visa versa.
This is due to the latiency of the moving gasses.

The exact same applies to breathers.
If it is right at idle it will be wrong every else.
The breather on an A series twin is right at speeds just above idle
Why?
because at idle and particularly at idle in the sales room you don't want a big puddle of oil dropping from the bottom of the bike.
If you can dig up Rex Bunns blog on the developement of the breather you will see some tables & graphs of crankcase pressures against engine revolutions and another of flow vrs engine revolutions.
They clearly show the mass inertia effect and that over certain rev ranges the system actually reverses itself and the breathers actually suck.
This was when he stopped looking for better valve material and turned towards flow through sytems.
Up to 1/3 rpm the M20 is oil tight with just a slight puff from the breather at 2/3 rpm it blows a continious stread of oil from the breather and at WFO the breather is again clean but oil pours out of the crankcase into the primary.
Bike Beesa
Trevor