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BSA A65 LIGHTNING 1972 650cc VERTICAL OHV TWIN: OIL SUPPLY CONVERSION

Dec 7

Written by:
Monday, December 07, 2009 8:39:06 PM  RssIcon

{ There are 2 other blogs, see Archive 5th July 2008 & 24th September 2009}

 

Both BSA and Triumph made oil in frame models at the time their production was coming to an end in the 70’s, this design had 2 main problems. Despite both companies closing Triumph did manage a come back but sadly BSA was never seen again.

One; when the bike stood for any length of time the sump would fill with oil by draining from the oil tank, this equally applied to the conventional separate oil tank designs. The cause was gravity and an inadequate one-way ball and spring fitted between the oil pump and the crankcase.

The other, because of limited space for threaded pipe fittings the plumbing was push on rubber pipes clamped with hose clamps, as the bike got hot and because the pipes were right next to the crankcase so did the pipes and leaks then ensued.

Also, specifically on the BSA, the oil feed and return was through a triangular fitting that had a central bolt and 2 of O-ring seals,clamped to the underside of the crankcase.Originaloilpipeconnectortocrankcase

For meanness, the BSA designers placed the bolt exactly ½ inch (13 mm) above a bottom frame tube, so that you virtually needed to remove, or at least lift, the engine to be able to replace the O-rings, this was another source of potential leakage, especially, again, as the bike got hot and the O-rings got hard!

My 1972 BSA Oil in Frame A65 was no exception!

The first part of my solution, whilst rebuilding the engine, was to have the bottom of the crankcase welded up where the above plate fitted and tap 2 of ¼ BSP threads, fortunately I found 2 of 90 deg. bends that I was able to screw into the crankcase and point in the right direction.Fiitingsforunderthecrancase

I say lucky, because the 2 threaded holes now in the crankcase were very close to one another. I then fitted normal hose tails and the same push on rubber pipe. Solution to that area, but still push on rubber pipes.

The next phase, how to overcome the push on rubber pipes and convert to crimped reinforced thread connecting pipes and install an external pressure fitting,that would not allow gravity to feed oil into the sump but would allow the suction force of the oil pump to overcome the ball and spring. PressureVale

 

Space is very limited between the bottom of the crankcase and the frame tubes and from the oil tank (frame down tube) and the crankcase.

At the bottom of the oil-in-frame oil tank is a steel plate which when removed allows for cleaning or replacement of the oil feed filter,

Oilfilter

the hole in the top of the filter fits over a steel tube, oil supply, which exits a the bottom of the oil tank (frame down tube)

The plate also has a drain plug for oil change purpose.

There is not enough room to fit the external pressure fitting between the oil feed tube before the rubber tube passes under the engine and certainly not enough space between the engine and the frame even though the pressure valve is only 22 mm diameter.

My solution was to fit a steel pipe through the base plate and up behind the oil tank base, terminating with a male thread, so that space, although tight, allowed for all the required fittings

OilTankbaseplateconversion

Then it was a matter of measuring, making the in-between pipes and fitting them.

Alltheparts

All the fittings and modified base plate

A view of the completed solution, not the only one? but it solved all the problems,

as you can see space is limited

Veiwbetweentheengineframe

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7 comment(s) so far...


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Re: BSA A65 LIGHTNING 1972 650cc VERTICAL OHV TWIN: OIL SUPPLY CONVERSION

Interesting bit of plumbing.
Would you by any chance know what the oil pressure should be on this model.Have just rebuilt my engine and fitted an oil guage.When engine is hot pressure is 1 kpa at 40 mph,3 when cold.Does this sound right?

By NIGEL CUTTING on   Saturday, March 31, 2012 11:41:47 AM
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Re: BSA A65 LIGHTNING 1972 650cc VERTICAL OHV TWIN: OIL SUPPLY CONVERSION

Hi Nigel Are you reading the gage correctly, the figures you give are very low, have you also got the normal oil pressure sender / light conected? Most oil pressure sensors are set to turn the warning light of at about 5-7 psi (34-48 kpa). Minimum pressure at warm idel should be 10-15 psi (70-100 kpa) at mid range rev about 35-40 psi (240-275 kpa) the oil pressure reliefe valve is about 50 psi (345 kpa) Low oil pressure is normally due to the crank bush wear, or bad oil pump

By Len Harrison on   Sunday, April 01, 2012 4:00:58 PM
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Re: BSA A65 LIGHTNING 1972 650cc VERTICAL OHV TWIN: OIL SUPPLY CONVERSION

Actually i think it is outstanding post. Thank's a lot for your post.

By Oil Tank Removal NJ on   Saturday, January 26, 2013 10:15:01 AM
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Re: BSA A65 LIGHTNING 1972 650cc VERTICAL OHV TWIN: OIL SUPPLY CONVERSION

IMHO It is not a good idea to measure oil pressure on any trad Brit twin unless you enjoy stress and disapointment. If you can see oil returning to the tank when the engine is running let that suffice. If you are really bothered, bite the bullet and get an SRM end feed conversion. If your timing side bush is stuffed you will not require a micrometer to know of it. Death could not ignore the racket it will make.

Cheers Alan

By Lightning Al on   Sunday, February 24, 2013 8:52:19 PM
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Re: BSA A65 LIGHTNING 1972 650cc VERTICAL OHV TWIN: OIL SUPPLY CONVERSION

Alan I tend to agree but the SRM conversion is very expensive (especially from outside the UK) and I have had a few timing side bushes re-machined by a "magician" engineer who has been doing them for many years, and they run for years! If you change the oil frequently
Cheers Len

By Len on   Monday, February 25, 2013 3:04:24 PM
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Re: BSA A65 LIGHTNING 1972 650cc - oil filter...

Hi,

Loved your article! I have a '71 OIF Thunderbolt but the oil filter screen has a big split in it. I cannot find anywhere in Australia to get a replacement. Any idea where I can source one from? I was looking at a paper filter conversion kit instead but would like to keep the old girl as original as possible. I am in the process of rebuilding her afetr an extende3d stay in the shed (due to a split fuel tank - now fixed!).

Thanks

Toby

By Toby on   Thursday, July 11, 2013 5:57:44 AM
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Re: BSA A65 LIGHTNING 1972 650cc VERTICAL OHV TWIN: OIL SUPPLY CONVERSION

Try www.britishspares.com/ they are in New Zealand Part number is 83-3642

By Len Harrison on   Friday, July 12, 2013 4:00:19 PM

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