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#590813 - 03/19/15 2:01 pm A10 oil pressure..how would you ever know?  
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zoe Offline
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How would you ever know if your A10 had low oil pressure?

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#590814 - 03/19/15 2:15 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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Lew Graham Offline
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Christchurch New Zealand
If there is a loud bang and the drive side conrod has punched a hole through the crankcase, that would be a fair indication. At swap meets one finds that there are many more timing side crankcases for sale than drive side cases. This is the reason.

#590820 - 03/19/15 3:38 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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Alex Offline
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How would you ever know that your sludge trap is plugged?


A smattering:
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'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#590823 - 03/19/15 4:07 pm Re: A10 oil pressure..how would you ever know? [Re: Alex]  
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zoe Offline
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How would you ever know before it's too late? Since it's evidently not possible to check the pressure with a gauge what are the early signs of low oil pressure in an A10.

#590828 - 03/19/15 4:52 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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trevinoz Online content
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Even with good pressure, take note of Alex's post.

#590837 - 03/19/15 5:57 pm Re: A10 oil pressure..how would you ever know? [Re: trevinoz]  
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zoe Offline
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It seems you wouldn't know your sludge trap was plugged, or partially plugged, unless you remove the sludge trap plugs and clean everything out. What does that have to do with being able to detect dangerously low oil pressure before you throw a rod? Am I missing something? All I want to know is how to try to prevent the situation of a thrown rod, or some other catastrophic failure, before it happens due to low oil pressure and/or a too worn timing side bushing.

#590839 - 03/19/15 6:06 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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kommando Online content
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Scotland
You have no way of knowing but you can reduce the risk by futting a return line oil filter, unless you are doing big mileages that should be enough.

#590851 - 03/19/15 7:14 pm Re: A10 oil pressure..how would you ever know? [Re: kommando]  
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Hi All,
Quote:
what are the early signs of low oil pressure in an A10.

The first sign of low pressure on the A7 /10's is tappet clearance increasing
This is due to the PRV not opening and feeding oil to the cam trough
leading to worn cams / followers

2c
John

#590859 - 03/19/15 8:01 pm Re: A10 oil pressure..how would you ever know? [Re: chaterlea25]  
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zoe Offline
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What prompted my original question is that someone on this forum suggested that .004" clearance on the timing side bushing meant it needed replacing which I don't doubt, i.e. if a narrow, hand cut ~ 3/32" wide, piece of .004" shim stock would slip between the crankshaft journal and the bushing the bushing needed to be replaced. My Haynes manual says .0015" is ideal when new and .002" is the wear limit.

So, I can just barely, only at some locations within crankshaft rotation, get my .004" shim stock to slip in but I have no problems with valve adjustment or anything else, i.e the engine runs great, has good power, no noticeable wear particles in the oil, etc.

I'm not enticed to replace the bushing but I also don't want a catastrophic failure.....what to do?

#590865 - 03/19/15 9:04 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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DMadigan Online content
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Is the A10 OPRV the same as the A65 thread and diameter? I am making OPRVs with a -03 JIC port on a banjo that you will be able to connect to a pressure gauge.
If you can get a 0.004" shim between the crank and bush I would say it is well past worn. I know little about A10s except what is in Bacon's book but unless the pump is a lot greater capacity than an A65 the crank is probably looking to relieve itself of excess reciprocating weight soon. Power and running performance give little indication of connecting rod failure.

#590928 - 03/20/15 11:11 am Re: A10 oil pressure..how would you ever know? [Re: DMadigan]  
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Return flow in the oil tank indicates the oil pump is working ergo you have oil pressure.

#590937 - 03/20/15 11:42 am Re: A10 oil pressure..how would you ever know? [Re: LarryLebel]  
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zoe Offline
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The oil pump is working well as I have good flow back into the tank but I think I'll have to go to the trouble of installing a new timing side bushing based on what I'm hearing on this forum. Better safe than sorry.

#590941 - 03/20/15 12:12 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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kommando Online content
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Quote:
Return flow in the oil tank indicates the oil pump is working ergo you have oil pressure.


But if the OPRV is stuck open you have low oil pressure but as it dumps to the sump you will have good return. If the timing side bearing is shot again you get excess flow too early to the sump and good return to the oil tank. All good oil return flow shows is that oil is getting to the feed pump and then to the return pump, it tells you nothing about what is going on in between. To know the oil pressure you need a gauge.

#590943 - 03/20/15 12:33 pm Re: A10 oil pressure..how would you ever know? [Re: kommando]  
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zoe Offline
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Since it appears there is no way to check the pressure I'm left with no choice but to tear it down and install a new bushing with .0015" to .002" clearance and check and refresh everything else along the way. I like doing this stuff but it a a pain in the butt at the same time. Peace of mind is worth the effort as the risk of losing a case with the original factory case would be somewhat of a disaster value wise.

#590946 - 03/20/15 12:43 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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Rickman Offline
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..........
Plus the thought of it going BANG! somewhere far from home, or at speed, or cranked over in a turn...

If you REALLY want to cover ALL the bases, years ago, I had a friend who's engine went BANG! because the flywheel broke in three!

Maybe have the crank and flywheel magnafluxed? Nitrided?

Last edited by Rickman; 03/20/15 12:46 pm.
#590953 - 03/20/15 1:22 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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After initially riding a BSA Bantam (the normal first bike in UK in those days) in 1964 I bought a 1960 A7 Shooting Star. After about a month I was going about 70 mph down the local dual carriage way (the place to see "what'll it do") when there was a loud bang and no power.
I was lucky that the engine had not seized but the primary side rod had made a nice hole in the crankcases--about two inches by two inches.
With not a lot of mechanical knowledge at that time--and no real experience of motorcycle engineering--I had a real stroke of luck. The father of a friend of a friend heard about it and said "bring it around-we will have a look at it". Only turned out that he was an ex road racer--having raced in the immediate post war years against Geoff Duke etc. He taught me how to strip the motor. Then the next stroke of luck--he was then the superintendent of the light machine shop of a big local engineering company (employing about 12,000 people). So the crankcase half went into the trike bath for several days and was then welded up by a Lloyds accredited welder using what was then the new fangled Argon Arc process for welding aluminum.
We built the bike back up and it was as good as new until I sold it about 9 years later.
So--having seen the results of a thrown rod--Zoe--attend to the problem before it throws a rod--not afterwards.
And to my late mentor----R.I.P. John Thomas

#590956 - 03/20/15 1:35 pm Re: A10 oil pressure..how would you ever know? [Re: DMadigan]  
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If you can lift the crankshaft 4 thou, I don't think your engine is safe to run.


Amateur Loctite enthusiast.
#590972 - 03/20/15 3:52 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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My point was that you can't monitor everything going on in your engine. To some extent you always have to rely on your ability (or the person your paying) to put the thing together right. Particularly on a road bike where you're usually operating well below the limits.

Trying to use oil pressure to diagnose whether or not .004" of radial clearance in the timing side bearing is ok is a whole 'nother bag of nuts. The simple answer is: the bearing is shot, time to tear it down. That will solve your oil pressure gauge installation problem.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#590987 - 03/20/15 5:11 pm Re: A10 oil pressure..how would you ever know? [Re: DMadigan]  
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Originally Posted By DMadigan
Is the A10 OPRV the same as the A65 thread and diameter? I am making OPRVs with a -03 JIC port on a banjo that you will be able to connect to a pressure gauge.
If you can get a 0.004" shim between the crank and bush I would say it is well past worn. I know little about A10s except what is in Bacon's book but unless the pump is a lot greater capacity than an A65 the crank is probably looking to relieve itself of excess reciprocating weight soon. Power and running performance give little indication of connecting rod failure.


I am interested in your A65 PRV. My mate is just about to finish rebuilding his Spitfire MkIV and it would be really nice to monitor the oil pressure when starting it up.
Can you supply one? And send it to Norway?

#591013 - 03/20/15 9:20 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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Jon, I have not got the pieces from the shop yet. Then I have to make a check on the relief pressure.

#591036 - 03/20/15 11:49 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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Mr Mike Offline
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I am not familiar with the A-10 OPRV. You can modify the A65 OPRV so you can use a test gauge. I used to do it so I could check my oil pressure at least annually ON MY a65. I had the same concerns as you, Zoe. I have now converted to a new pressure control system of my own design that permits a gauge to be installed. I have pictured it before on this site.

Mr Mike

#591041 - 03/21/15 12:49 am Re: A10 oil pressure..how would you ever know? [Re: Mr Mike]  
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zoe Offline
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Is the oiling system similar enough on the A10 to the A65 that I could install a fitting on the A10 OPRV cap to which a pressure gauge could be fitted?
I've now got my engine apart and will install a properly fitted timing side bushing anyway but I would like to be able to check the pressure in the future.

#591153 - 03/21/15 5:07 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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Mr Mike Offline
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Zoe,
An easy way to make a test setup is to find an early OPRV with the flat hex cap. Drill and tap for 1/8th NPT for a 90 degree fitting and a gauge. Temporarily plug the return port. Easy on A65 with 8-32 set screw, not sure on A10. You can also solder up the bypass holes on the A65 plunger. This will give a test port. Bear in mind you will have no pressure relief. The firt time I tried this I ruined a nice oil filled gauge when I pegged it on startup at. Warming oil first will help and you may only be able to run at idle if you have good oil pressure.

Mr Mike

#591234 - 03/22/15 8:12 am Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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Hey Zoe
Did you remove your slud trap? If so what did you find? Jeff

#591328 - 03/22/15 5:08 pm Re: A10 oil pressure..how would you ever know? [Re: zoe]  
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same comment as Mr Mike above , only difference was I wrecked a manky old gauge so wasn't as pissed off. All I did was use an old A10 OPV and make a brass "collar\' to go inside to blank off the holes then just reduced the male thread down with all sorts of fittings till I had one a gauge would go on. With effectively no OPV it shot straight up to max (100psi gauge) ...I killed the motor straight away.

I just needed to see the pressure once to be happy and forget about it ...so far so good.


"There's the way it ought to be and there's the way it is" (Sgt Barnes)

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