Author Topic: Flexible joins on oil pipes.  (Read 1023 times)

Offline v8ivor

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Flexible joins on oil pipes.
« on: 11.01. 2016 18:46 »
The A10 plunger build that I'm working on is not going to be standard stock. On saying that, I am not destroying or customising any original parts that I have, just making do with what I can find. I want to plumb the oil pipes with copper pipe and brass fittings (Brazing the joints ) But I would like to join the flow and return pipes between the gearbox and timing case with Prestex couplings, Who thinks that this is a BAD idea rather than using flexible pipe that would limit any vibration cracks ?

Offline bikerbob

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Re: Flexible joins on oil pipes.
« Reply #1 on: 11.01. 2016 20:14 »
The flow and return pipe are flexible for a reason to stop them cracking, your oil feed to the rockers should also have between the oil tank return pipe and the rockers a short section of either rubber or plastic tubing. Solid copper pipe is asking for trouble.

Offline Derby Rob

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Re: Flexible joins on oil pipes.
« Reply #2 on: 15.01. 2016 20:18 »
hi, as i understand it copper pipe will " work harden" and crack with age and vibration ,i would go with flexible pipe myself.
61 BSA A7,yamaha rd500 ,suzuki ts250er,suzuki x7,1958 francis barnett cruiser 80

Offline v8ivor

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Re: Flexible joins on oil pipes.
« Reply #3 on: 15.01. 2016 22:12 »
Although the old Indians and Harley's had plenty of ridged oil and fuel pipes, I don't think they were copper.

Online bsa-bill

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Re: Flexible joins on oil pipes.
« Reply #4 on: 16.01. 2016 09:45 »
Quote
Although the old Indians and Harley's had plenty of ridged oil and fuel pipes

photos of old bikes/machines with copper pipes often show a coil in the pipe, I always assumed this was to dampen any vibes and so prevent the pipes cracking, flexi pipe much better in my opinion
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline BSA_54A10

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Re: Flexible joins on oil pipes.
« Reply #5 on: 16.01. 2016 14:26 »
Nope.
The coil is there to compensate for different expansion rates between the external copper tube and the two end of the engine.
Same reason BSA oil banjos are not a strait piece of pipe.
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Trevor

Offline v8ivor

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Re: Flexible joins on oil pipes.
« Reply #6 on: 16.01. 2016 14:31 »
I agree with you Bill, to be safe, but my Indian 4 has copper pipes from both tanks to the carb with soft solder joints and my old Chief had 4 copper pipes from the oil tank (Without loops ) Yet my old WLA had a looped gas pipe that I think was steel. But as this is a BSA so I will use flexible joints.

Online bsa-bill

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Re: Flexible joins on oil pipes.
« Reply #7 on: 16.01. 2016 19:47 »
I stand corrected Trevor *smile*
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline olev

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Re: Flexible joins on oil pipes.
« Reply #8 on: 16.01. 2016 23:52 »
You could be partially right, Bill.
in industry, copper sheathed pyro electrical cables and 1/4'' copper pneumatic control lines had vibration loops adjacent to their connections to machinery.
This was to stop the copper breaking at the compression gland.
It might not be an issue with a soldered joint?
cheers

Offline BSA_54A10

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Re: Flexible joins on oil pipes.
« Reply #9 on: 17.01. 2016 04:42 »
big difference between  an electrical cable and a copper pipe.
Way back when steam was in common use and before the slip coupling had been invented steam pipes had little omega looking bends to allow for expansion when the pipes were being steamed and contraction when they were not.
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Trevor

Offline shuswapkev

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Re: Flexible joins on oil pipes.
« Reply #10 on: 17.01. 2016 07:03 »
they used copper when as oil proof rubber hadn't yet been invented.....and even for quite a few years...wasn't really available to motorbikers...likely very expensive...

  I reckon steel is better than copper...but definitely would have a rubber section for vibration and heat movement....  I get my rubber hose from hydraulic places...the budget auto suppliers have some they seem to think allright...but...not something you can afford a failure on

Online Triton Thrasher

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Re: Flexible joins on oil pipes.
« Reply #11 on: 17.01. 2016 09:41 »
Oddly enough, stainless steel also has fatigue issues.

For reliability, the rigid metal section should be no more than a stub that you fix the flexible hose onto.

Online bsa-bill

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Re: Flexible joins on oil pipes.
« Reply #12 on: 17.01. 2016 09:54 »
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For reliability, the rigid metal section should be no more than a stub that you fix the flexible hose onto

see where your coming from TT but I'm thinking that due to the very small holes that the rocker feed studs have in them and the not so great oil pressure that leads to them would a long run of rubber not (that will be to some degree expandable) loose pressure.

This is the great thing about this forum, random queries lead to lots of info that is of benefit to many of us
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline duTch

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Re: Flexible joins on oil pipes.
« Reply #13 on: 17.01. 2016 10:40 »

 I get your drift Bill, but given that the rockers are fed By 'excess' from the return which has an unrestricted hole, I can't see there'd be much pressure to lose anyway. ..? 
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Offline BSA_54A10

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Re: Flexible joins on oil pipes.
« Reply #14 on: 17.01. 2016 10:40 »
FWIW I use teflon tube inside stainless braid.
Works really well, fixed end on the engine and slip joint on the oil tank.
Oddly enough I get tons of nitwits criticising my bike but on one ever picks out the oil lines.
Cost a bit to get made up but I will never need to make any new ones again forever.
Bike Beesa
Trevor