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#833352 12/15/20 3:35 am
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At 1500rpm I have 10psi, at 1000rpm it's down to 5 or 6 psi. The pressure does go up as the rpms go up. Should I even be riding the bike with this oil pressure? The oil light does not come on.

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Are the pressures you quote hot or cold?
What are the pressures at higher revs? (hot or cold).
How are you measuring the pressure?
Just to understand the situation better you understand.

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The oil switch setting is 7-11 PSI so if you are reading 5-6 PSI then the switch is bad or the wrong one. A Triumph twin perhaps?

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Originally Posted by DMadigan
The oil switch setting is 7-11 PSI so if you are reading 5-6 PSI then the switch is bad or the wrong one.

I'm not sure that's correct.

The switch listed in the T160 parts book is 60-3719, Smiths PS 5330/1/03.

As I understand it, the suffix denotes the switch operating pressure* which, if correct, would make it a 3 psi switch.

*(this is mentioned in A65 manuals)



Originally Posted by DMadigan
A Triumph twin perhaps?

A Triumph twin switch would normally also be 60-3719* and I'm not aware of there being 'high' and 'low' pressure standard versions of 60-3719 switch.

*(earlier tapered thread and D2133 switches discussed at great length elsewhere).

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Missed it was for a T160. The '72 R3 parts book gives the switch as 5300/1/07 and the repair Manual gives the pressure as 7-11 PSI. The T150 workshop manal also gives the switch pressure as 7-11 PSI.
Is the 3 PSI 5330/1/03 switch change another of the T160 "over 200 improvements"? Or was it to keep the twin/triple parts count low?

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What is the hot oil pressure at 4000 rpm. Should be above 60 psi. Should be around 20-30 at 1000 rpm hot. I wouldn't ride it otherwise.


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I didn't take note of the rpms to psi as when I was riding there was 30,40,50 psi and thought all was good. I will take another ride and take note. I installed a Triples Unlimited oil pressure gauge.

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Hi Thomas,
Originally Posted by Woodsie
At 1500rpm I have 10psi, at 1000rpm it's down to 5 or 6 psi.
I'm guessing this is is when the engine's good 'n' hot? If so, seems low. However, ...

Originally Posted by Woodsie
I installed a Triples Unlimited oil pressure gauge.
... first thing I'd try is another gauge - I appreciate not cheap, but cheaper than rebuilding a triple engine that didn't need it ... unless you want a reason for taking your T160's engine to bits? wink

If the above pressures are with the engine hot, just as a matter of interest, what are they when the engine's cold?

Also, from the fitting instructions Les Williams sent out with his T160 oil pressure gauge kits:-
Quote
Oil pressure should read up to 80 psi when cold and 25-75 psi when running hot at 3500rpm. Please note that these readings depend entirely upon the condition of the engine
... this suggests potentially more variation than the workshop manuals' "Normal running ... 85-75 p.s.i." or even the "10 psi per thousand rpm" rule-of-thumb?

Hth.

Regards,

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Hi,
Originally Posted by L.A.B.
The switch listed in the T160 parts book is 60-3719, Smiths PS 5330/1/03.
As I understand it, the suffix denotes the switch operating pressure* which, if correct, would make it a 3 psi switch.
*(this is mentioned in A65 manuals)
The T160 workshop Manual appears to confirm - ""Switch operating pressure ... 3-5 p.s.i.".

Hth.

Regards,

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Originally Posted by Stuart
Hi,
Originally Posted by L.A.B.
The switch listed in the T160 parts book is 60-3719, Smiths PS 5330/1/03.
As I understand it, the suffix denotes the switch operating pressure* which, if correct, would make it a 3 psi switch.
*(this is mentioned in A65 manuals)
The T160 workshop Manual appears to confirm - ""Switch operating pressure ... 3-5 p.s.i.".

Hth.

Regards,

...And in section H17 it's "7-11 lb.".

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Originally Posted by L.A.B.
...And in section H17 it's "7-11 lb.".
cool

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The engine was hot when the oil pressure was low at idle. At start up the pressure is over 100psi. I will source another gauge. I definitely am not looking for a reason to tear the engine down. I will take it for a ride this weekend and take note of the pressures and rpms.

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Hi Thomas,
Originally Posted by Woodsie
I will source another gauge.
Just a thought, Triples Rule is in the US ...

Hth.

Regards,

Last edited by Stuart; 12/16/20 7:33 pm.
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Most auto shops have oil pressure gauges, many with compression fittings. Smallest 270 degree gauge that I found is 1-1/2". Wallmart has one for $10.48.
https://www.walmart.com/ip/1-1-2-Oi...ower-Mount-Connection-0-100PSI/217305475
https://www.walmart.com/ip/LYUMO-Mi...-160psi-0-10bar-1-8-NPT-Thread/538723906
You could use nylon hose with a compression to NPS adapter temporarily. NPS might be hard to find but short term you can use NPT, just do not tighten more than about 1/4 turn past hand tight.

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Thank you for the links DMadigan.

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I replaced the oil pressure gauge and my readings are almost identical to David P's pressures. I removed the OPRV today and all seems well with it. Can you just pull it apart, clean it and use it again or is replacing it a safer bet?

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Originally Posted by htown
What is the hot oil pressure at 4000 rpm. Should be above 60 psi. Should be around 20-30 at 1000 rpm hot. I wouldn't ride it otherwise.
Now you see our confusion. We get one answer like this.
And another like this
Originally Posted by Stuart
Also, from the fitting instructions Les Williams sent out with his T160 oil pressure gauge kits:-
Quote
Oil pressure should read up to 80 psi when cold and 25-75 psi when running hot at 3500rpm. Please note that these readings depend entirely upon the condition of the engine
... this suggests potentially more variation than the workshop manuals' "Normal running ... 85-75 p.s.i." or even the "10 psi per thousand rpm" rule-of-thumb?
Am I to believe that 1. I shouldn't ride the bike when it shows 40-50 psi with warm oil at 3500rpm? or 2. Les Williams says it's okay with as little as 25 psi?

BTW: I used to see the oil light flashing at idle when I returned from a ride. I replaced the sender with another of the same type, 5300/1/07, and now the light stays off. The gauge still reads 10 psi or under.


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We had 2 T-160's until a few years ago. Both had o/p gauges fitted. Bikes in Fl. Cold at start up almost 100 psi, after 10 mile easy warm up on the twister, 60-65 psi. Idle hot 30 psi. Both engines had standard cranks with std. rod & main brgs. Engines redone by me and Jim Crompton who was a BSA dealer and drag & RR'd R-3's. Both engines had NOS brgs. Jim had. Mine had std. bore, wifes was at .040. Both heads with Kibblewhite guides with seals on the intake. Valves OEM with slight reface and seats cut 3 angle with a Neuway cutters. Both on stock cams and tappets. The OP was with Valvoline VR-1 60wt. Hot ambiant 3/4 of the year. If temp got to 60 degrees or less a piece of cardboard across the oil/rad held on with hair ty's for easy to remove has the day warmed. John Healy & Phil Pick both have addressed 3cyl. O/P in tech articles over the years. Being the T-160 had the latest greatest oiling system upgrade the O/P was way better than T-150's & R-3's. These bikes don't tolerate hamfisted owners. Well sorted the are damn fine rides. Used many years by marshals @ IOM and until recently the last non Japanese bike to win the Daytona 200 when it was a real international event!!

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Is there a measurement for the length of the spring in the OPRV. The oprv came out relatively easy but it looks like it will be a bear to get back in!

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Woodsie, when you are finally done with your OPRV consider oil change to SAE 10W60 full synthetic. Castrol Edge in my area, but don't know what is available in yours, I also used German made Liqui Moly 10W60 with good results. It's expensive oil, but a cheap protection against engine problems.
Your hot oil pressure should read little higher with this oil than regular 20W50 and I found it helping in really hot weather.
My bike is closer to Les Williams figures with oil pressure, never went higher than 85 psi, but holds around 50 psi on 3500 rpm and 15 - 20 psi on hot idle which is between 1000 and 1500 rpm for me.

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The old rule of thumb was "10psi per 1000 rpm" with engine oil warm.
The oil pressure registered is only an indication of the output of the pump, the OPRV and the state of the bearings.
It is not an indication of the pressure between the shells and the crank--which is many times more than the input pressure as registered on a gage
You have a gage fitted--my advice would be to continue to ride the bike until your pressures go down to the "rule of thumb".
Your bearings are partly worn but have some life still left in them.
Not ideal but we can't have our engines always in new pristine condition--otherwise we would be putting in new shells every 5 minutes.
HTH

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Okay, so maybe I'll get one more season out of it and hope I won't need to have the crank ground when I get around to it. The people who can do that properly are pretty scarce these days.


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Hi David, Richard,
Originally Posted by DavidP
Now you see our confusion.
I don't see "confusion"? confused Both are opinions. Les based his opinion on: tearing down more triple engines than you and I have had hot dinners, including standard road bikes, modified road bikes, factory racers, factory production racer Slippery Sam after it had won five Isle Of Man Production TT's in a row (most races ~200 miles, last one ~400 miles); his business rep. up to 1992 (when he sold the business), etc.

Originally Posted by Tridentman
The oil pressure registered
is not an indication of the pressure between the shells and the crank
Mmmm ... the pressure take-off Les used is one of the drillings in the front of the centre crankcase; wouldn't this be the pressure between centre main-bearing shells and the crank? Or do you mean between the big-end shells and the crank?

Originally Posted by Tridentman
The old rule of thumb was "10psi per 1000 rpm" with engine oil warm.
my advice would be to continue to ride the bike until your pressures go down to the "rule of thumb".
+1.

Hth.

Regards,

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Thank you for all the sage advice. I'm going to relax and enjoy the bike.

Before I put the OPRV back in, I have a spring length of a whisker under 1.5", is this an okay length?

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Tridentman was talking about the hydrodynamic pressure in the bearing itself which is far higher than the pump pressure that is feeding it.
I have never seen the need for 10W-60 oil, 20W-50 is fine or even 10W-40 just like any normal bearing shelled engine. Too thick oil is going to heat up more and increase the temperature in the shells.
If you are concerned about the OPRV it should be pressure checked for leakage and relief pressure. Spring length will not tell you much unless you know the rate. Springs sag over time with load and temperature.Triumph twin OPRVs will fatigue faster because of the constant pressure variation of the pump. The triple gear pump has more uniform flow so the piston is not constantly moving back and forth.

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The often quoted 10 psi per 1000 rpm is just an an opinion from years ago. Many engines would not be happy with 30 psi at 3000 rpm during heavy power loading. And many engines never need more that 60 psi no matter what the rpm or load...It's really a matter of engine design...


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Big D Cycle in Dallas can do your triple crankshaft correctly. They did mine several years ago. I was at the same point at that time. 35-40 psi hot at 4000 rpm, around 10 at idle. John Healy responded on another forum to my post and recommended redoing the bottom end. On tear down the main saddle bearings were worn but not completely shot. Crank was reground 10 under and new bearings fitted. Also an NOS oil pump and new OPRV from SRM. Oil pressure is now 75-80 hot running and 30 at idle. I wouldn't say a triple engine was any harder to work on than a twin. Only tricky part was fitting middle piston. Install in block first then put the rod cap on through the sump opening in the bottom of the cases.

Last edited by htown70; 02/14/21 5:49 pm.
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Hi

For what it's worth, I recently purchased a oprv spring from LPW 1.5"

Regards


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3000 rpm on a triple is lugging it--they do not come on the boil until about 4500 rpm.
So--warm up the engine slowly and then ride it keeping it on the boil at over 4500 rpm and you will be able to postpone bottom end work for a while.
If you have 35 psi at 4000 rpm then you are under the level of the rule of thumb and should seriously consider getting the bottom end done before you have a disaster.
Fine judgement required!

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I appreciate everyones insight and opinions, good stuff. Thanks. I can't wait for Summer

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