Oil pressure relief valve shims (2008)

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Reggie, your numbers seem pretty high to me. But I use 20W-50 syn and that may explain much of it. If it works, great, but I would worry about some of those numbers, particularly the cold ones.

Having said which, I defer to the experts, whom I hope will chime in.
 
Yesterday, I removed the pressure release valve and took out two shims. I also changed the oil for SAE40. This dropped the cold pressure to about 60psi/65psi, at a fast tickover.

What I do find interesting is that within about a minute, the cold oil pressure starts to drop quite quickly, as the oil starts to heat up. I know this is obvious, but it is how quickly that the difference in readings happens that suprised me.

I went for about a 30 mile thrash, and most of the time, the engine was making just over 10psi per 1,000rpm, for example at 3,000rpm, 35psi to 40psi which I was quite happy with, but by the time I had arrived home, it was just under 10psi per 1,000rpm, for example at 3,000rpm, 25psi, but this was on a very hot engine.

As I understand it, putting shims back in will not alter the "very hot" oil pressure readings, so I suppose that although not worryingly low when "very hot", my only solution to this would probably to put back some SAE 50? I'll probably give it a couple of more runs before I make any decisions.

Just out of interest, I had used the "Mick Hemmings" method to end up with two shims in my pressure release valve. Mine is an after market stainless steel version. I don't know if that is likely to make it different in its characteristics to a proper Norton type. I wouldn't have thought so?
 
Reggie said:
Mine is an after market stainless steel version. I don't know if that is likely to make it different in its characteristics to a proper Norton type.
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Did you buy it from a specialist Norton parts supplier, or just someone who sells British bike parts?

Is it the correct 'flat domed' Norton item?
 
I've just had a look . The dome is flat. Is that an oxymoron?

This part was already on the bike when I bought it, so I do not know where its origins are from.

Was there a round dome type on earlier Nortons?
 
Reggie said:
Was there a round dome type on earlier Nortons?
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I don't think so, but I think it is possible to fit the BSA/Triumph type?

They are normally fully domed and set at a higher release pressure.
 
Interesting to know about the Mick Hemmings tips. I have his engine rebuild DVD but must have missed that.

As it turns out though, that's exactly how I have my 750's relief valve shimmed. I have one shim in there and the relief valve fires at about 60 psi according to my OldBritts oil pressure gauge.

I'll have to double check the 850 before the first startup (coming soon!)

Debby
 
debby said:
Interesting to know about the Mick Hemmings tips. I have his engine rebuild DVD but must have missed that.
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It's at 1 hr. 09 mins. into disc 2 (rebuild disc).
 
I use 20W-50 syn and hot idle tends to be about 20 PSI. I haven't been into the timing chest yet (I will soon, to put in an RMA cam chain adjuster). Cold starts go to maybe 60 PSI tops. Hot running tends to be about 40 PSI (I run between maybe 2500-3500 RPM for the most part). Motor seems to be healthy.
 
Yes, I can see them. :)

Greg, what is that "clear grease" that you use for priming the pump and where does one obtain it?

Do you lap the brass end plate or just the body?

Debby
 
The grease is called Super Lube Synthetic Grease about a dollar an oz.
Made by NSF http://www.jamestowndistributors.com/us ... rosion+Gel

Dow 111 is also used on the gaskets and the double00 plumbing washer.
Yes the brass plate is lapped along with the body. I was just trying to show that it is not a hard job to get to know what the oil pump is up to and how good your filtering has been. Little hunks of valve spring are very scary objects and after 34 years it's time to look for yourself.
 
Searched out this thread as I had my valve apart a couple of weeks ago and found to my surprise, it had no shims at all. Had the bike since Adam and Eve, but don't remember ever taking shims out or even having the valve apart more than once, so it must have been that way from new. Went to replace the copper washer between the dome and the body and found the new one to be one heck of a lot thicker than the one (paper thin) that was in there, so I lapped the old one and ran a torch over it to soften it and just put it back in. Reason for not using the new thicker one was that if I thought about it, the thickness of a new washer is the deciding factor as to whether or not you need shims, and how many. A thick washer sets the clearance inside large and a super thin washer will reduce the inside clearance and accordingly the number or shims needed to take up the slack. I suppose if I can, I will check the oil pressure but since the oil pump pumps to the holding tank and the motor isn't overly loud, it will be the old ignorance is bliss thing. Perhaps I'm lucky and the Mick Hemming adjust is already in place due to the super thin washer. Comments?
 
I agree, the thickness of the washer is going to affect the relief valve blow-off pressure slightly, although once the oil has warmed up and thinned out, then the oil pressure isn't likely to reach the relief pressure, -even if the valve was set a bit on the low side?
So the thicker washer probably wouldn't do any harm?

A pressure test could at least give some warning of impending disaster, but would have to be done fairly regularly to monitor any gradual or sudden deterioration in oil pressure?
 
I don't even know what a shim looks like, so no idea how thick they are, but that copper washer I almost put in was about 3-4 times the thickness of the one I put back in, so I bet it would have effected the adjust of the valve. Moot point at this stage of the game though, as I essentially didn't change the adjust I have had in the machine for at least 30 years by replacing the old washer. May come to me ordering a new one as it might be the source of the small leak that is somewhere in that region of the motor, then I would Mick Hemmings it and see what the old adjust was. Won't build it out though, just to see, if it doesn't leak. Lazy guy...sleeping dogs :wink:
 
hewhoistoolazytologin said:
I don't even know what a shim looks like, so no idea how thick they are
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They are small steel discs approximately 0.430" (10.9mm) in diameter x 0.0355" (0.9mm) thick.
 
Hi , I will "refresh" that post....very bad weather here , so what could I do ?? great idea plumbing an oil gauge : presto buy a smiths 2" gauge (new?)on the bay , buy BSF double banjo bolt some goodridge braided line, and fittings (demon tweeks have the correct flat bsp at a decent cost), trim a piece of alloy , fix it between clocks , start the bike (in fact all those preliminaries took me ages ......!), and bingo no leaks , happy I am......BUT the gauge shows a 100 psi ++++ (needle blocked at the upper limit scale), scratch my old head > faulty "new" gauge ? and bingo went on the forum and found that old 2008 link.....take another OPRV on another cdo, (from which I can hear the famous piston slap), fit it and the pressure went down to a reasonnable reading , dismantle the previous one ( no noise when shaking it , and five or six washers ) here I am ....
work in progress......!!!!!!!!
 
The relief valve had so many shims in it that it could not open?
 
Yes , I think so , just back from the shed , there was definttly six washer , and no slapping noise when shaking , my own fault......!
now I will check them all..........
 
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