Author Topic: crankcase pressure etc  (Read 6648 times)

Offline Rocket Racer

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 1379
  • Karma: 16
  • A kiwi with a racing A10 rig
    • NZ Classic Sidecar Racing
Re: crankcase pressure etc
« Reply #45 on: 04.10. 2017 04:04 »
I run bunn breathers on my road rocket, I am forced to run catch bottles on both the inlet (the timed breather) as well as the exhaust on the rocker gear. In my case I'm also trying to expel methanol fumes rather than have them gather in the crank where I'll end up with water if left unchecked.
I still have trouble fully sealing the top end rocker box 3 gaskets but partially put this down to the fretting rocker box suffers from due to vibration through the head steady at the rev's I'm running which are typically in the 6-7000 range but have been seen to hit 7500.

On my road going 60 SR I had to replace the tacho cable to remove leaks, but my race RR runs the taccho driven cable which doesnt suffer those problems

Yes many oil rings are rubbish.
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

Offline t20racerman

  • A's Best Friend
  • ***
  • Join Date: Feb 2011
  • Posts: 227
  • Karma: 7
  • Keep it nailed!
    • The T20 'Super Six' Suzuki website
Re: crankcase pressure etc
« Reply #46 on: 04.10. 2017 06:31 »
"That's why I'm trying to get one of these:

http://www.ebay.com/itm/Stoney-Racing-Oil-Catch-Can-One-Way-Non-Return-Check-Valve-PCV-Breather-Hose-/182462713511

Unfortunately out of stock. ☹️"


Here is another option:

https://www.mikesxs.net/catalogsearch/result/?q=breather+REED+VALVE

Looks ideal - but they want to charge me $117 for postage to the UK! 🤤
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Online duTch

  • Ricketty Rocketty Golden Flashback
  • Wise & Enlightened
  • *
  • Join Date: Oct 2011
  • Posts: 4519
  • Karma: 40
Re: crankcase pressure etc
« Reply #47 on: 04.10. 2017 07:57 »
Quote
......On my road going 60 SR I had to replace the tacho cable to remove leaks, but my race RR runs the taccho driven cable which doesnt suffer those problems. .........

 Is there something wrong with that statement ? doesn't quite make sense to me...but many things don't
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

Offline coater87

  • Wise & Enlightened
  • *
  • Join Date: Jul 2008
  • Posts: 1181
  • Karma: 6
Re: crankcase pressure etc
« Reply #48 on: 04.10. 2017 15:23 »
"That's why I'm trying to get one of these:

http://www.ebay.com/itm/Stoney-Racing-Oil-Catch-Can-One-Way-Non-Return-Check-Valve-PCV-Breather-Hose-/182462713511

Unfortunately out of stock. ☹️"


Here is another option:

https://www.mikesxs.net/catalogsearch/result/?q=breather+REED+VALVE

Looks ideal - but they want to charge me $117 for postage to the UK! 🤤

 high postage cost? Welcome to the world of owners living in the U.S.

 Its ridiculous, and I am going to say 18-24% of the cost of my rebuild is due to postage. *sad2*

 Lee
Central Wisconsin in the U.S.

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8027
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: crankcase pressure etc
« Reply #49 on: 04.10. 2017 20:32 »
Either way it would be better with two. One in and one out like the Bunn breather set up I have on my Cafe. The timed breather is disabled. https://www.a7a10.net/forum/index.php?topic=8292.msg58577#msg58577
 Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Online Sluggo

  • Serial Hoarder, or Eccentric Collector depending on viewpoint
  • Resident Legend
  • *****
  • Join Date: Jun 2017
  • Posts: 623
  • Karma: 11
Re: crankcase pressure etc
« Reply #50 on: 04.10. 2017 21:30 »
This all has been a very interesting topic and read it front to back.  It seems topical and resurges in interest often with different makes and models.  Some years back I worked a spell on a bike backlog for a local shop and they carried a number of bikes modern and vintage.  The owner was very interested in the BUNN Breather issue for some of the modern Enfields as we built hot rodded versions for some customers.  People tend to get tunnel vision and not look beyond their specific make and model.  At that time I amassed a huge amount of discussions and tech materials from a wide range of sources and shared it with the brain trust at that shop.
We concluded that the BUNN breather had merits but anyone could make their own versions and I suspect thats what did in the supplier.

This topic is hotly debated on Norton forums and seems to be several different guys supplying their perfect mousetrap for Nortons.  Some of them are quite clever and well engineered albeit expensive however some just modify and adapt a japanese bike metal PCV flapper valve and that seems to work for a fraction of cost.

I used to build some V8 performance engines and we installed a few with a vacuum pump setup that worked really well,  Eliminated leaks, increased ring sealing and slight boost in power. You can make your own but Moroso sells kits.  Not totally feasible on a A10 but the concepts are worthy of study for a better understanding.

I have some HD bikes and multiple Buells, As universally known HDs are known themselves for leaking oil.  Buells design for their breather system is I believe the final word on solving these issues in reasonable way.  The sportster engine design ran a number of case breather setups as well as eventually having breathers thru the cylinder heads with "Breather Bolts" that vented INTO the air cleaner which created a slight vacuum as well as met EPA emissions requirements.
But Buell changed that system into a baffled breather system out the TOP of the cylinder heads with PCV valves and hoses. (Again culminating into the intake)  Many people in the Buell world have setup alternatives where they go to a check valved catch can,  or vent openly but most agree the top of the head PCV valve setup works really well.  Many other V Twin models now copy this design as well or adapt this system.

I have greatly angered some BSA owners in the past arguing the timed disc setups in BSA Singles and twins is inadequate (FACTORY STOCK IS BEST you heretic!)  But simple testing shows thats not true.  I do think on a BSA Preunit twin that the venting from the case UP thru the head is problematic  but could be addressed easily enough but likely would be visible externally.    It seems logically that 2 large fittings (one at the head and one off the case) into a good PCV-check valve set up would be the way to go.
I am not going to tell you guys what you have to do, but instead encourage you all to look at what other makes and models do like I did and adapt what works best for your situation,.
Remember that any advice received on a free internet forum is generally worth about 1/2 of what you paid for it.
We overcharge every 3rd customer to pass the savings onto you.
You can have High Quality, Low price, and fast turnaround. Pick any 2, Never all 3 at the same time.

Offline t20racerman

  • A's Best Friend
  • ***
  • Join Date: Feb 2011
  • Posts: 227
  • Karma: 7
  • Keep it nailed!
    • The T20 'Super Six' Suzuki website
Re: crankcase pressure etc
« Reply #51 on: 06.10. 2017 16:17 »
Either way it would be better with two. One in and one out like the Bunn breather set up I have on my Cafe. The timed breather is disabled. https://www.a7a10.net/forum/index.php?topic=8292.msg58577#msg58577
 Cheers

That is an excellent looking system muskrat - thanks. I'll definitely look into doing that :-)  A couple of things though:

 - Taking the air in from the top sounds good with respect to cooling (and air flow through the engine) but is the original venting between the crankcases and the rocker box up to the job for moving air quickly in and out? I wondered if it was a bit restricted? Did you mod this in your engine?

- Here's the best Bunn breather I can find to buy anywhere in the UK:
http://triumphbonneville.com/store/engi.html (scroll down on the page a bit...)
This was recommended on the thread you pointed me to. Have you or anyone experience of this particular system? Looks good to me, and happy to buy it, but just wondered if it was what I need.

Thanks, as always to all, for the amazing help and technical info on this forum. :-)

Adrian

1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Offline t20racerman

  • A's Best Friend
  • ***
  • Join Date: Feb 2011
  • Posts: 227
  • Karma: 7
  • Keep it nailed!
    • The T20 'Super Six' Suzuki website
Re: crankcase pressure etc
« Reply #52 on: 06.10. 2017 19:04 »
Sluggo - a very interesting post. Combined with muskrat's observations, it seems clear that this is the way to go. :-)

I chatted with a Commando guy at work today and he was of the same opinion, but also pointed out that this was a VERY contentious subject for some of the 'you can't beat the std set-up' guys who inhabit a lot of Norton forums. Twas ever thus...  ;)
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8027
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: crankcase pressure etc
« Reply #53 on: 06.10. 2017 20:23 »
G'day t20.
Yes I have the Bunn breathers on my Cafe. It works great, the motor accelerates a lot quicker and no oil leaks. That kit from Shropshire is identical to mine. I'm surprised to see one for sale as the Bunn has been out of production for years.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Offline t20racerman

  • A's Best Friend
  • ***
  • Join Date: Feb 2011
  • Posts: 227
  • Karma: 7
  • Keep it nailed!
    • The T20 'Super Six' Suzuki website
Re: crankcase pressure etc
« Reply #54 on: 06.10. 2017 21:28 »
G'day t20.
Yes I have the Bunn breathers on my Cafe. It works great, the motor accelerates a lot quicker and no oil leaks. That kit from Shropshire is identical to mine. I'm surprised to see one for sale as the Bunn has been out of production for years.
Cheers

Thanks so much for the reply muskrat - really appreciated. Have just ordered the kit.... :-)

Oh, one other thing muskrat - have you improved the internal breathing between the rocker cover and the crankcases - or is yours just as BSA made it?
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8027
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: crankcase pressure etc
« Reply #55 on: 07.10. 2017 10:42 »
G'day t20.
No alteration to the oil drain holes. All breathing is from top to bottom (in via ex cover out via std breather hole) so it helps rid the rockerbox of spent oil.
At idle you can hear the valves working.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Offline Topdad

  • bob hebdon
  • Wise & Enlightened
  • *
  • Join Date: May 2011
  • Posts: 2215
  • Karma: 32
  • l
Re: crankcase pressure etc
« Reply #56 on: 09.10. 2017 15:43 »
Hi T20 any chance of some pictures showing how you fitted it ? cheers bob
" rules are made for the guidance of wise men and the blind obediance of fools"
United Kingdom

Offline t20racerman

  • A's Best Friend
  • ***
  • Join Date: Feb 2011
  • Posts: 227
  • Karma: 7
  • Keep it nailed!
    • The T20 'Super Six' Suzuki website
Re: crankcase pressure etc
« Reply #57 on: 10.10. 2017 20:07 »
Will do. Haven't got the bits yet though. I'm off work in two weeks, so should be sorting it then  - and hopefully fitting a 5 speed gearbox at the same time :-)
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Offline Cleve

  • Active
  • *
  • Join Date: Jan 2016
  • Posts: 8
  • Karma: 0
Re: crankcase pressure etc
« Reply #58 on: 11.04. 2019 17:57 »
Hi

I'd be really interested to read the pdf but the link doesn't seem to work?

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8027
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: crankcase pressure etc
« Reply #59 on: 11.04. 2019 22:36 »
G'day Cleve.
I see the original didn't work but a link in another topic did (https://www.a7a10.net/forum/index.php?topic=3634.msg24978#msg24978). Try this http://www.a7a10.net/BSA/oba.pdf
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7