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Oil Pressure #747750
09/03/18 3:41 pm
09/03/18 3:41 pm
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eelmgren Offline OP
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I bought a 1970 A65 as a project. It ran well but oil pressure went from 45 to 0 after about 5 miles and the low oil pressure light was on at idle. I measured play on the timing side bush, both clearance and float were about 4 thousands. I replaced rod big end bearings, timing side bush and set the float. Just got it back together. Started second kick. But, ... Oil pressure is about 40 at start and reads about 0 after 10 miles, tho the light didn't come on even at idle. I'm assuming the gauge reads a little low since the light didn't come on, but pressure shouldn't be dropping like it is. The pump looked OK and turned freely but I didn't take it apart. Should I suspect the pump?

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Re: Oil Pressure [Re: eelmgren] #747757
09/03/18 4:15 pm
09/03/18 4:15 pm
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did you send the crank out to check the clearances?? On BSA's that has to be perfect to maintain proper oil pressure. Also the pump needs to up to snuff too. Many on this board have beat this subject to death. However, everyone I have ever done has maintained the proper oil pressure when done with care. If the crank throws and bush journal are a little off they need to be brought back into the proper specs. These things do not oil like a triumph they feed and build pressure up through the bush, so they need to be tight. Oil pumps need to be checked and brought into specs. Do they need an oil cooler? they don't hurt, I always use one on a modified BSA , just a smaller one mounted to the front. With 20 50 oil my latest will maintain 40 pounds at 2500 rpm hot and rise to 45 above 3000 rpm. This is what they are supposed to have. I rebuild triumph and BSA twins and have found for the most part that machine shops that usually do not work on these things leave a little to be desired. So I send out integral parts to machine shops I know understand what they are dealing with. A good one is E and V engineering in Mich that specialize in these engines. So if you just cleaned the sludge trap ( hope you did) and installed new rod bearings and a std bush uou may not be in specs to have good oil pressure when the engine gets warm. Did you at least mike it all? to see where you are at? They can look good but be worn enough to lose pressure, especially on a BSA, they are touchy. There are services they can perform to make it oil like a triumph that work great, but are expensive compared to a std rebuild. Good luck. Now watch and see how many chime in to say they run their beezers with 20 pounds of oil pressure!! I just wont do it, I have been Hi Sided by them old BSA's that were running great with piss flow oil pressure, till they seized up.LOL

Re: Oil Pressure [Re: eelmgren] #747760
09/03/18 4:22 pm
09/03/18 4:22 pm
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PS. your 1970 should have the DD pump im it which is the better alloy pump. Perhaps someone changed it to the less desirable pump of earlier years that do not have the volume of the later pumps. You can visually look at the pump to plainly see the two capital DD's etched into it. Also you can tell if its early by looking at the bottom plate, it will be held in with screws, the later ones with bolts. They do make a big difference but you should have some pressure after 5 or 10 miles. That's barley stretching its legs.

Re: Oil Pressure [Re: eelmgren] #747762
09/03/18 4:36 pm
09/03/18 4:36 pm
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eelmgren Offline OP
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All clearances were checked. As I said timing side bush and rod big end bearings were replaced. Machine work & lower end was assembled by one who has been working these bikes for decades


"but you should have some pressure after 5 or 10 miles. That's barley stretching its legs"

No, -pressure starts good, then goes down. It appears as the oil warms pressure decreases.-

Re: Oil Pressure [Re: eelmgren] #747768
09/03/18 4:59 pm
09/03/18 4:59 pm
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Rotherham - S. Yorkshire
Allan Gill Offline

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Who’s Oprv Are you using? Is it a piston or ball type?


For 70 it should be a piston type, but if you have one of those shiny stainless SRM types (and I like most their products) I have found 3 to have stick. If they stick open you have the biggest problem. There are still some Original old stock BSA oprv’s knocking around in the states. I bought a couple and they have been fine. Checked them out and sealed them with rtv silicone.
I’d rather use the ball type over the SRM unit and found that with 20-50 oil the ball type didn’t have the light coming on when hot... the SRM unit did.

The next point to mention is that flow is more important than pressure. If you block the end of the journal (like what happens when the bearing shells are melting around the crank... the oil pressure will be fantastic.... does this still mean the engine is good? No

Another thing is the quality of oil will improve or lessen the chances of self distraction over a cooler. If the oil isn’t hot enough then (say your using a multi grade) it will not react with the modifiers and you’ll be left with a 20 oil.

If the rings have bedded in, I switch to an Ester based fully synthetic instead of mineral. The molecules reform in harsher conditions than the mineral oil and will last much longer. When using a semi synthetic I had starved the engine of oil (long story) but the engine ran 20 miles with no oil at all. It wouldn’t have done that on a mineral oil.... the additive pack did its job and the engine didn’t blow up. Had it a low flow rate and low pressure I may never have noticed.


beerchug
Re: Oil Pressure [Re: eelmgren] #747770
09/03/18 5:10 pm
09/03/18 5:10 pm
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Which pressure relief is installed? The ball type or piston type? Piston type is the best and can be installed in the ball type cavity. If t has a piston type, have you had it apart to make sure the spring is ok and the piston isn’t sticking?

What are you using for a washer under the OPRV? Sometimes the washer provided with gasket kits is way too thick. You want about 1/32” washer. I chamfer the case and use an O-ring for a seal.

If you didn’t go through the pump, you likely need to. The DD pumps are definitely the best alloy pumps, but the regular D’s are good as well. Are the pump screws tight enough. There is a fine line between tight enough and too tigh. If the pump body bolts are a little loose can cause loss of oil between pump sections.

Is the pump flat as well as the mounting flange on the cases? Do the holes around the pump area have burrs? And fit issues here will cause oil loss. Is the pump studs tight?

And one more thing to check....BSA sometimes did a p*ss poor job of drilling the cavity for the pressure switch into the oil galley. I have seen cases where you could barely poke a small torch cleaning file through the opening. Those engines always showed low oil pressure when warm. Other cases had a nice large hole.


Life is too short to drink cheap, bad beer.
Re: Oil Pressure [Re: eelmgren] #747772
09/03/18 5:49 pm
09/03/18 5:49 pm
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I understand that the clearances were checked. Did the crank need turned? Did you turn the throws but not the bush journal? Just curious as to what the specs were. Like I said, they have to be right on, not off a little on either one and the TB off a little too. It all adds up on a BSA. You can get away with that on a triumph but not a BSA. Guess Id check the pump to make sure it isn't worn out. If its good, then Id open the bottom up. Not questioning your mechanic and machine shop but Ive torn down plenty of BSA's that were supposed to be fresh that had no oil pressure when they warmed up only to find that the throws and bush journal were off and needed to be brought to tight tolerances. Just out of curiosity how tight did the crank fit into the bush when you were checking end play? was it a bitch to get it in and out? or did it fall into the case easy and were you able to remove it easy? If so, that's where id start looking. Good Luck.

Re: Oil Pressure [Re: eelmgren] #747778
09/03/18 6:41 pm
09/03/18 6:41 pm
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Not surprising you have no pressure. 0.004" of clearance on the timing bush is twice the limit. You only had pressure at warm up because the oil was thick.

Re: Oil Pressure [Re: eelmgren] #747801
09/03/18 7:59 pm
09/03/18 7:59 pm
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argyll. scotland, uk
gavin eisler Offline
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Was the TS main journal ground fresh with the new bush? It reads like you fitted a new bush but left the journal as found.?
The factory way was to supply accurately sized bushes to fit a crank ground to fixed undersizes.
More common now is to grind the crank just enough to make it round then bore /ream the new bush to size, leaving the desired 0.0015" fit. How was yours done?

New oil pumps are out there, SRM make good ones, or you could be a guinea pig for the new Hepolite iron pump.

Old pump can be fitted with new gears, ( if you can find them, they are out there), old pumps can develop excess end float , ie the gears are not well supported sealing on the flat sides, you can lose this by lapping down the pump body until when test assembled there is just a wee bit of drag. This is tedious, Ive done it with my old iron pump, but with the old alloy type you might be pissing into the wind if the body is warped , which they can do.
Much easier to fit a new pump, and if you didnt check the pump seat is flat , better do that first , they are usually bumpy, the alloy round the mounting bolts pulls up. Check by bluing the pump face lightly , trial fit and look for witness marks,, expect to see rings of blue round the two body mount hols., scrape the blued areas, rinse / repeat till happy/ fed up.

Last edited by gavin eisler; 09/03/18 9:49 pm. Reason: too many zeros in the fit

71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Oil Pressure [Re: gavin eisler] #747804
09/03/18 8:58 pm
09/03/18 8:58 pm
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eelmgren Offline OP
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The crank wasn't ground. It looked and measured good. The bush was fitted to the crank, again by somebody who has been working and racing these bikes for decades. I think he's considered something of a wizard around here. He also put the case together. I fitted everything else. I put a straight edge on the pump, it didn't appear warped, but I didn't blue it and check for contact marks. Guess I'll have to pull the pump off and look at it more closely when I have a chance. Was hoping to ride it to the Barber Festival this year.

Re: Oil Pressure [Re: eelmgren] #747816
09/03/18 10:02 pm
09/03/18 10:02 pm
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If the bloke who put the bottom end together was good, the problem is probably the relief valve either sticking open or not seating in the cases.
Try that before taking the timing covers off.
The bottom end is like a car bottom end, oil to the crank is fed via a bush so the clearance must be within spec and the pump reasonably good.
There is no special magic required on these motors, just thorough mechanics and reasonable engineering skill.


Lamas are bigger than frogs.
No room for sanity here.
Re: Oil Pressure [Re: eelmgren] #747817
09/03/18 10:02 pm
09/03/18 10:02 pm
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gavin eisler Offline
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The pump can be tested in situ , if the crank pinion , worm gear is removed , jury rig a short rubber hose with a screw driver bit stuck in to the end of the pump, drive with power drill , observe it doing its thing, a good way to see if its leaking at the pump or not.,oil should appear around the TS bush,

If you take it to bits to look at the pump , and relief valve, look hard at how the relief valve threads into the body.
Its good practice to put a bit of thread sealer stuff on the inner female threads to give the valve a fighting chance of sealing HP from LP across three pretty loose threads.
While you are at it get a clock gauge , mount to read crank movement diametrically at the TS end , nudge the crank up against the dial to check bush clearance, more than 0.002" is a fail, ish, if its not done many hours it should still be a fresh 0.0015". ,


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Oil Pressure [Re: NickL] #747860
09/04/18 5:32 am
09/04/18 5:32 am
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Rotherham - S. Yorkshire
Allan Gill Offline

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Originally Posted by NickL
If the bloke who put the bottom end together was good, the problem is probably the relief valve either sticking open or not seating in the cases.
Try that before taking the timing covers off.
The bottom end is like a car bottom end, oil to the crank is fed via a bush so the clearance must be within spec and the pump reasonably good.
There is no special magic required on these motors, just thorough mechanics and reasonable engineering skill.


Thanks for echoing my sentiments Nick,

To add I have seen a high mileage motor with more than the required end float giving good oil pressure, the one I mentioned earlier where the oprv was swapped and all was well.


beerchug
Re: Oil Pressure [Re: eelmgren] #748804
09/11/18 9:06 pm
09/11/18 9:06 pm
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eelmgren Offline OP
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Update-

Replacing the relief valve was easiest so I've done that first. The old valve had the course screen which I understand is for the triples.
With the new valve- when cold, pressure reads 50-75, it was below 50 with the old valve.
After the engine warms it goes down to about 25 at (I'm guessing) @3000 rpm and at idle the light come on.
I'm still not ready to suspect a bad bottom end job - so I'm guessing oil pump?

I've got a cheap oil pressure gauge on a tee fitting with the pressure switch. I don't know how accurate the gauge is but when both the light is on and the gauge reads zero I think I can assume pressure is low.

I wonder if whoever had this bike before me had the same problem and thought a higher pressure relief valve would fix it-

Re: Oil Pressure [Re: eelmgren] #748813
09/11/18 10:51 pm
09/11/18 10:51 pm
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NickL Online content
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You cannot go by the coarse/fine mesh on the valve, that changed week by week, i've had beezer twin ones that had coarse mesh.

Did you use some sealant around the inner threads with the new valve?

If it's dropping to 25psi at 3k when hot with 20-50 oil then there is a problem with either the pump or the bottom end.
If you have some patience and time you can rebuild the pump correcting any warping and truing the flat surfaces,
once that's done you can then re-size the gears so they rotate freely. The job takes typically 4-16 hours by hand.
Most people get another or a new pump......
As a simple test, fill the pump with oil and block the outlet side off with your finger, if when you rotate the pump by hand you
cannot retain the pressure with your finger and oil is not leaking out around the base plate or centre joint, the pump is ok.


Lamas are bigger than frogs.
No room for sanity here.
Re: Oil Pressure [Re: eelmgren] #748822
09/12/18 12:27 am
09/12/18 12:27 am
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sloppyoil Offline
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I know this has been beat to the ground but what exactly do you consider warmed up? If you ride the machine a mile or two that's not enough, need to run it at least 15 miles to make sure everything is warmed up. The higher pressure that is occurring 50 to 75 cold is more than likely caused by a longer spring or a spring that has been modified by stretching. If the engine is in good shape it will build oil pressure to the pound of the relief spring. If it has 0 when its idling after a quick warm up either your pump is wasted or the clearances are to loose on the throws and bush.

Re: Oil Pressure [Re: eelmgren] #748829
09/12/18 1:11 am
09/12/18 1:11 am
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gavin eisler Offline
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If all is good.
I consider fully heat soaked as 5K + for 50 miles, expect the oil light to flicker at idle.

If its worn out , you need 5K to make it go out.
Anything in between will get you home.

Last edited by gavin eisler; 09/12/18 1:14 am.

71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Oil Pressure [Re: eelmgren] #748840
09/12/18 2:49 am
09/12/18 2:49 am
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Magnolia, TX
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Flickering light at idle should go out by 1500 rpm when hot.


1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: Oil Pressure [Re: eelmgren] #749058
09/13/18 7:50 pm
09/13/18 7:50 pm
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eelmgren Offline OP
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Did you use some sealant around the inner threads with the new valve?
No, I have now

what exactly do you consider warmed up?
I assume it is warm when the oil is thin enough to make the pressure decrease. This has been about 5 miles.


I removed the inner timing cover and worm gear. I spun up the pump (clockwise looking front to back). I didn't see any oil coming from the pump, but there was a good flow from the timing side bush. How much oil should I see? How much is excessive?
I have the pump accessible. I may as well remove it and take a closer look.

Re: Oil Pressure [Re: eelmgren] #749063
09/13/18 8:19 pm
09/13/18 8:19 pm
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A good flow of oil from the timing side bush is not a good sign. There should only be a slight seepage. A flow means the oil is leaking out around the crank and not going to the rod bearings the way it should. Sounds like the bush is worn. That could explain the low pressures you are getting. You should be seeing around 40 psi at 3500 rpm after a ten mile ride on a 75 degree F day.
You really need to check the condition of the bush. Normal clearance should be .0015, .0030 is too worn to use. You can check it by mounting a dial indicator gauge and moving the crank end up and down. I highly recommend you buy the book. Building Budget Brits by Mike Brown. He has a good description of problems with BSA bottom ends.
I would not ride the bike as it is now. Starving the rod bearings will lead to a big bang.


1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: Oil Pressure [Re: eelmgren] #749065
09/13/18 8:44 pm
09/13/18 8:44 pm
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Adam M. Online content
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Low oil pressure is a common problem for big majority of BSA A65 owners.
I had it as well. Flickering oil light on idle after every more spirited ride I did.
And it persevered with freshly rebuilt engine with the best BSA made iron oil pump I paid good money for
and all the possible tricks with relief valve done.
I decided to ignore it, after first few years of ownership and no visible ill effects to the engine.
I used the best fully synthetic 20W50 engine oil ( Amsoil, Royal Purple, Loqui Moly,.Mobil 1 ) and set my idle
higher - 1000 / 1200 revs/min - it killed my flickering oil light.
The engine rebuilt in 2006 was used for 10 years of my ownership without any problems ( and I didn't babied it - revs between 6 -7k was used quite often on lower gears ).
Bike was sold to the new owner last summer and I didn't hear any complains about it's ability to run further smile.
My engine had an oil filter installed after rebuilt, which was a big part of it's success, I believe.

Re: Oil Pressure [Re: eelmgren] #749071
09/13/18 10:24 pm
09/13/18 10:24 pm
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eelmgren Offline OP
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WOW - So many differing opinions

The engine has about 20 miles since overhaul. New bush and was reamed to fit the crank. Again, the bottom end was done by someone who has been working these for decades. He's in his 70's and still races them every weekend. I suspecting something other than the engine.

I opened up the pump. Didn't look bad other than being very dirty.

Re: Oil Pressure [Re: eelmgren] #749074
09/13/18 10:42 pm
09/13/18 10:42 pm
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Not many different opinions really.
An oil filter is a VERY good idea, you can plumb one into the return line.
The switch for the oil light should be a 5lb one.
The relief valve should seat properly and be sealed to the inner threads.
The pump should work and be fitted properly.
The oil should be 20w/50.
The timing side bush should have no more than a 1.6 thou clearance.


Lamas are bigger than frogs.
No room for sanity here.
Re: Oil Pressure [Re: eelmgren] #749078
09/13/18 11:23 pm
09/13/18 11:23 pm
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Well, you have answered your own question when you stated a good amount of oil is coming out of the bush area. Shouldn't be hardly any or none would be perfection. That's how a bsa builds the pressure. if its leaking out with a drill at low rpm cold just imagine how much is pouring out when its hot, and starving the rod brgs. The clearances are off, either he cut to much off or he didn't mic it correct. Tear it apart and send the crank out to E and V engineering and have then clearance the whole shebang for you, that way it wont go boom.

Re: Oil Pressure [Re: eelmgren] #749082
09/13/18 11:34 pm
09/13/18 11:34 pm
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At the very least check the crank movement with a dial indicator gauge while you have the timing cover off. Pull the intermediate gear first, just mark it well. Plus you got a rebuilt bottom end and you say the pump is dirty. Says something about the workmanship of the guy doing the rebuild.

Last edited by htown; 09/13/18 11:36 pm.

1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: Oil Pressure [Re: eelmgren] #749089
09/14/18 12:15 am
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If you can get bigger than a 2 thou feeler gauge into the bush/crank journal when cold, the clearance is too big.


Lamas are bigger than frogs.
No room for sanity here.
Re: Oil Pressure [Re: eelmgren] #749099
09/14/18 1:19 am
09/14/18 1:19 am
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Posts: 1,351
Magnolia, TX
htown Offline
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htown  Offline
BritBike Forum member
Joined: Mar 2006
Posts: 1,351
Magnolia, TX
See page 40 in this mag for an article on how to check the clearance. Very easy to do and will give you peace of mind that it is correct. But if you would rather spend days debating with people on here that's your option.
https://books.google.com/books?id=g...amp;q=measuring%20bsa%20bush&f=false

Last edited by htown; 09/14/18 1:22 am.

1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: Oil Pressure [Re: eelmgren] #749276
09/15/18 3:00 pm
09/15/18 3:00 pm
Joined: Sep 2014
Posts: 84
GA
E
eelmgren Offline OP
BritBike Forum member
eelmgren  Offline OP
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E
Joined: Sep 2014
Posts: 84
GA
In all fairness, the dirty oil pump was on me. My engine guy only had the case halves, crank, cam and con rods.

I don't have the time now so this project will get pushed to the back of the garage once again. I'm putting it back together and will run it to see if cleaning and reassembling the oil pump made any difference at all, but I am starting to suspect the bush wasn't reamed correctly.

I put the pump and inner timing cover back on yesterday. Today I opened the timing hole on the front of the engine case and oil flowed out. Does this mean the oil pump check valve didn't seat?

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