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When speaking of front or rear it is usually describing the front of the bike or the rear of the bike. When talking about a V twin bike, you don't say the left or right cylinder because you're standing next to it. Apology accepted.
True... but I wasn't really talking about a motorcycle. I was referring to the photograph of the pipe/manifold assembly you posted. If you were holding it in your hand with the manifold on the right as it is in the photo, the return line is in front. :) As long as you're happy with the way you've got it connected then all is well and there's no longer any confusion.
 

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Discussion Starter #22 (Edited)
I see your point but I was referring to the pipe which is in front... the one in front of the other. The one nearest you as you look at them. My apologies if I've confused things... my logic always was a bit skewed from most folk's.
Okay so if I understand youse-guys, the front pipe is the suction and the rear pipe is the return?
When facing the engine from the kick start side, the outboard pipe is the return and the inboard pipe is the suction; this is how mine's plumbed.
I have no pressure at the pressure switch port however, I do have some drips of fresh oil. I'll try the compressed air recommendation tomorrow.
It worked normally a year ago when I moth-balled it. Flushed Oil Tank, cleaned the bird n' rock screen, installed new hoses, have good oil flow to the junction block.
Don't have enough inner reserve HP to kick 200-300 times nor enough family members or neighbors to accomplish that task.
 

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And remember...the pre unit connections are opposite the unit engine..

I've started many Triumphs after having the engine disassembled or if it was sitting for a time...I always use a oil pressure gauge for the initial start up and it can take 10-15 seconds to show pressure..
 

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What is the tread size of the pressure port? 1/8NPT or BHP?
That depends.

Pete said:
Since 1970,the thread in the timing case has been 1/8" NSP (27 tpi,parallel thread).The fitting,or pressure switch,is meant to pull up against a sealing washer.
Don't use 1/8 NPT (27 tpi,tapered thread);you risk damaging the thread or splitting the case.
Some were built in '69 with 1/8 NPT (tapered thread).
'68 and earlier use 3/8" x 26 tpi BSC thread,and a sealing washer.
 

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Discussion Starter #28
Mine is a late 1969 build. I have to consult both the '69 and "70 parts manuals.
When I pulled the sensor it definitely has a tapered thread and uses a thin fiber washer.
 

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Discussion Starter #30 (Edited)
Prime the sump.

As the OP and to close the loop on this thread, I had to prime the sump with 1 pint of oil and it solved the LOP/no return to the tank problem.
Thanks to everyone for their recommendations.
Don
 

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Hi,

What is the tread size of the pressure port? 1/8NPT or BHP?
That depends.
Pete said:
Since 1970,the thread in the timing case has been 1/8" NSP (27 tpi,parallel thread).The fitting,or pressure switch,is meant to pull up against a sealing washer.
Don't use 1/8 NPT (27 tpi,tapered thread);you risk damaging the thread or splitting the case.
Some were built in '69 with 1/8 NPT (tapered thread).
'68 and earlier use 3/8" x 26 tpi BSC thread,and a sealing washer.
Curiously, no reference to the source of the quote from "Pete"; unfortunate, because it's almost all incorrect. :bluduh

All early '69-season twins and triples, Triumph and BSA, have 1/8"NPT (National Pipe Tapered)-thread switches. During the '69 season, all twins and triples, Triumph and BSA, changed to 1/8"NPS (National Pipe Straight (i.e. parallel))-thread switches. The change was recorded on Triumph triples to an AC-date-coded engine; Triumph twins changed much earlier; unfortunately, the engine number isn't recorded but I know of October-1968-built one-owner bikes with NPS-thread switches.

Pete said:
Don't use 1/8 NPT (27 tpi,tapered thread);you risk damaging the thread or splitting the case.
This is simply twaddle. :( The OD of NPS and the maximum OD of NPT are exactly the same - 0.405"; NPT tapers down from maximum.

Unfortunately, (one of?) the switch maker(s) - presumably a Far Eastern subsidiary of Richard Cranium Ltd. - either releases batches every now-and-then, or one batch that has hung around since God was a boy, where the thread tapers up from 0.405" ... :eek:

It is only these incorrect switches that damage thread or timing cover. However, if you never use a spanner/wrench to fit the switch, only thumb-'n'-forefinger 'til the switch is fully-seated, you will never damage thread or cover. :thumb

Pete said:
'68 and earlier use 3/8" x 26 tpi BSC thread,and a sealing washer.
This is only true of the 650's, and it isn't for a pressure switch. It was simply for an oilway drilling into the timing cover; the blanking bolt is Cycle because the more-usual BSF thread is 20 tpi and presumably wasn't considered fine enough for a pressure seal. When Meriden had to fit a pressure switch to 650's, this blanking hole thread was considered the easiest to adapt for the switch.

Hth.

Regards,
 

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Hi Deltapapa, Most interesting outcome. Very glad you got it going.

Something you did cured the oil light not coming on that was not related to priming the sump. That is what is interesting...

The feed & return of the pump are completely stand alone systems housed in 1 casting. The feed & return pump's only real common denominator is the drive block. Understanding pressure to crank & oil pressure light is the feed plunger, return to tank is the scavenge plunger. That is why priming the sump cannot effect the feed side.

Of course the return oil lubricates the rockers, but that is not part of the "feed system". Rocker lube it is a function of the return system.

So you were either not waiting long enough for the pump to make pressure on the feed side to turn out the light or fiddling with things disloged a piece of dirt or something in the check ball. Remember oil returning to tank has no relationship with the oil light turning off.

My hunch is you got lucky & the dirt in the pump ball floated off with whatever you was doing. Blowing air, or pumping oil into the feed line will dislodge dirt like this sometimes.

Of course the feed has to work before the system fills the sump. It can take longer to fill the sump & start returning than we sometimes think. Still priming sump is not needed, it will prime on its own.

Again, filling sump with 1 pint & seeing return has nothing to do with oil pressure getting to the crank.

Did you replace the oil pressure switch? Did you ever check feed pressure with a gauge?

Funny thing how these old bikes can do odd things & you really can't put a finger on exactly what the cause was.

My bike is due for an oil change in the next week or so. I'm going to set a stop watch & measure how long it takes for oil pressure light to go out & how long it takes for return to show in reservoir.

I always clean reservoir screen & drain eng sump & clean that screen. Done dozens of these oil changes & never ever primed sump.

The return system is kind of interesting. When oil is in sump it pumps it out & then sucks air. When it sucks air you notice the return at tank stops momentarily. Of course the feed side of pump is pumping oil into crankshaft & the pressure release valve. The normal leak off of oil from these drains into sump. However the oil has to be deep enough in sump for pump to self prime & start pumping again. It takes many strokes of the plunger to do this. There is a suck air & then pump oil back cycle that goes on continuously. Sounds crazy, but in practice it works quite good.

Again, glad your back on the road before the cold sets in.
Don
 

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Discussion Starter #33
T-man,
I did not apply any compressed air to anything, nor did I install a pressure gage.
I explained my predicament to my British bike expert here in OK and he recommended adding a pint to the sump via the timing port.
I did this and immediately had return oil to the tank. It took about 15-20 seconds for the LOP light to go out.
Don
 
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