Can oil pump be bench tested?

NickZ

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I have the timing cover off my 71 Roadster in order to adjust the camshaft chain. The bike has just over 23,000 miles on it. While I'm in there I'll install new seals on camshaft & crankshaft and oil pump.
I do have an issue with oil draining from tank to sump when the bike is idle for several days. I have the oil pump out and measured its end float to be 0.0015". I compare that to a spare pump which measured 0.0005" end float.
It would be convenient for me to just install the spare pump to get the bike back on the road and refurbish the original pump later. But I am a little concerned about putting an unknown pump in without assuring myself that it is functional. I picked this spare up with a bunch of parts I bought and do not know much about its history. I think it came from a 1973 850 engine. Other items that came with that bunch of parts have had issues. Is there a way to bench test an oil pump to be sure it is functional?
 
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Yes, but it will need you to build a test rig, a spare timing side crankcase would be a good start and then you need a way to drive the pump, read the revs and read the pressure.
 

NickZ

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It really doesn't take all that long to lap a pump so why not do it? The instructions are in the factory manual section C25.
I was planning to go that route till I read this thread:

The 4 bolts are definitely center punched and I gather from that thread that it will require a delicate grinding operation to get them out without negatively impacting the threads of the brass plate on the bottom. C25 doesn't mention that step, but if necessary, makes it not such a straightforward task.
 

NickZ

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Yes, but it will need you to build a test rig, a spare timing side crankcase would be a good start and then you need a way to drive the pump, read the revs and read the pressure.
Hmmmmm, sounds like this might be more effort than just refurbishing the original pump, as LAB suggests.
 

L.A.B.

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I was planning to go that route till I read this thread:

The 4 bolts are definitely center punched and I gather from that thread that it will require a delicate grinding operation to get them out without negatively impacting the threads of the brass plate on the bottom. C25 doesn't mention that step, but if necessary, makes it not such a straightforward task.

My Commando's pump screws weren't centre punched. If they had then I would've used a small drill to remove the punched metal until the screws could be loosened.
 

Richard Tool

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The center punching ( staking when I was schooled) is no big deal .
A Dremel tool with a tiny burr or a drill and small bit used carefully can undo the deformed area . Lapping the pump is very simple .
I would add checking the keys/ key ways on shafts and cogs if not mentioned in the manual.
 

BERT

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I am in the same boat with this 72. I found some bits of gasket in the crankcase gallery behind the oil pump and rotating the worm gear can feel there may be a piece inside, along with a bit of end play. The lapping part is straight forward. The deburring is too. The screws can be replaced , but there is no listing in the factory parts list for the threaded backing plate if the threads end up being questionable for reasssembly. Is there a listing for another model year?
 

acadian

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Likely just needs to be lapped and tightened up, I recently received a new Andover pump which, on arrival, was not particularly tight. I stripped it, machined grooves for x-rings, then clamped it down tight in a bench vise for fastening.

IMG_3522.JPG
IMG_3521.JPG
IMG_3523.JPG
 
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@dynodave has bench tested many Norton oil pumps.
Ask him, he offers all kinds of Norton repair services.
Sorry-no
I did local club member testing, for many years, primarily for research and education for myself and local club friends.
Two tests, pressure rig for stationary static test for wet sumping potential, motor driven flow rig for dynamic flow and pressure measurements.
It would seem my research and results are challenged or outright rejected. Open offer for factory shop manual "rebuild"...no...testing...no We're obviously not on the same page as to working on and verifying the condition of NHT pumps.
Flow testing I consider too time consuming, time expensive yet under appreciated.
 
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Google translate does a reasonable job. based on page 1.
Nice , hope it works for you ! can help for few things if you need , I had even spoken of you to the guy about the X-ring you fit on the shaft and post a pic (sorry no copyright for you !! ) and ask him if he could translate in english to put on this forum.............
 
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No copyright, I just copied AMR and took their O ring size and looked up the matching X ring.
 

NickZ

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I just discovered another issue to IMG_8736.JPG consider. I noticed that the original pump from my '71 and the spare that i think is from a '73 850 engine have different characteristics:
Brass plate:
Original= 1.83" x 1.18"
Spare= 2.00" x 1.15"

Length of shaft beyond drive gear:
Original= 0.35"
Spare= 0.50"

Also, the body of the original pump has a bevel on the outside of the lower stud hole that the spare does not have.

So, the body of the spare is slightly larger and the length of its shaft is slightly longer than the original pump. The spare unit fits into the 71 engine nicely.

I see from prior threads that there were pumps for earlier Norton heavy twins that were built slightly different. I wonder if my 71 has one of these?
Anybody know if there would be a performance difference between these 2 pumps?
 
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Your pix does not appear to be both 6 start drive gears RH is 3 start LH is 6 start
Oiling a 750 or 828 is identical.
While not 100% cosmetically identical, all pumps originating from large diameter crank engines 66+ will interchange.
1960+ 650 and 750 have a smaller inlet and used usually on 3 start gears but would still work OK for a street motor as a 6 start
500-600 1.5" cranks have narrow gears. I think they are not made any more so wide gear is now used as 3 start only.
More nitpicky differences ...
 
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