Topic: Oil pressure and Tappet covers

[kingrabbit]

Re 1975 CB750F
Almost everything is stock
Question is about oil pressure vs oil circulation to the top end.

I have owned this bike for several years and it was very reliable and smooth. Like sewing machine smooth. This summer it developed some clacking noise. I tweaked the timing, the valve clearances and the cam chain tensioner. Synched the carbs. The clacking is still there.
I read on here somewhere that with the bike running I should get oil splashing if I remove tappet cover. I do not. Zero splash.
I changed the oil and filter.
I pulled oil pan off and the pump. The filter screen was clean. Very little debris in oil pan. The pump gear turned freely and moved oil in the process.
The oil gauge shows pressure.
Oil in tank moves when engine runs.
The clacking is still there. Bike gets hot and does not have the top end power it should have.

So the question is is it possible to have oil pressure but no circulation to the valves? I think that’s what’s going on here.
How do I definitively diagnose this? What’s the fix?

[754]

 yes, very tiny oil feeds  to the cam, they plug up sometimes usually one side.
 then it eats your cam and rockers. an early clue  your valves will need adjusting often,
 it seems to happen more if an amateur has re assembled the top end.
 
 so remove the 4 other caps,  I am guessing one side has oil, the other not. it will be wet inside and around the valve stem where the keepers are.

[ekpent]

 Any signs on the engine that silicone gasket sealer was used anywhere on any of the covers etc.. No oil flow would wipe things out fairly quickly. If you wanted to do a really good inspection sometime by removing the valve cover and cam the engine will have to come out if the frame if stock.

[kingrabbit]

There are no signs of bodged repairs. Bike is pretty tight until this started. So I removed all 8 valve covers and ran it a minute. No oil splashing or spraying or misting out of there.
Oil light went out when bike started. Pressure gauge shows pressure. Like 60 psi.
How do I know it’s plugged oil feeds vs pump?
I read on here somewhere a stuck valve in the  pressure pump can cause this issue? Assuming it’s that pump that provides the oil to the top end...

[Bodi]

If you see 60psi at the gallery, the pump is OK. The valvegear gets oil through small orifice restrictors, not a lot of oil is needed up there and it isn't pressure fed to the cam "bearings", cam faces, and rocker faces etc. like the main bearings require... this lets enough oil through to lube the valvegear and maintains system pressure for what needs it.
A total lack of top end oil means, fairly quickly, major damage. Looking in the tappet covers, are the parts visibly wet with oil?
Yes? might be OK but further inspection would be good. You should see slinging drops or mist in there with the engine running, much of the lubrication is via splash from the rotating cam. No oil flying around = something is wrong.
No? needs disassembly and full inspection for valvegear damage, and to see why the oil flow has been blocked. The bottom end can be assumed OK as you have had good oil pressure.
The question about silicon is important. Using silicon to seal gaskets and particularly the main case split will make a lot of little silicon chunks from where the stuff squeezes out on assembly tightening. These just fall off pretty quickly when the engine heats up, fall into the oil. Not a big problem, the oil filter will catch chunks... until the oil filter gets clogged with them, causing the filter bypass valve to open and let them on into the oil gallery.
Naturally anything that can't go through the restrictor orifice will jam in it and block oil flow. Reduced flow is not unusual, total blockage is pretty rare.
I don't know why Threebond/Hondabond doesn't do this. Maybe if someone went nuts with it and put a 1/4" bead around the case split it would, you want a very thin bead or film. But I have not see problems with the correct sealant used.

[ekpent]

 Blocked feed hole to the cam tower ='s this   

[754]

 Like I said take off the 4 outer caps, then are both sides just as wet ? if one side looks less wet, the oiling is compromised.
 when setting valves the feeler gauge always comes out wet. if the oiling is compromised, it will probably be almost dry.
 did you take a look?

[Jerry Rxman Griffin aka MuthaF'er]

Have you revved it up with the exhaust tappet covers off? It sprays better then with your best friend down there close looking for it 

[kingrabbit]

Looks like there is less oil circulation on 3-4. The attached pic is a bit of paper towel I positioned in front of the exhaust tappet holes.
What’s next?

[754]

Get in there with a strong flashlight, dark room.  Take all 4 caps off thecsuspect side, take a good look for wear or shavings, compare to good side for reference.
 You can try to put a q-tip down beside valvespring , try to sweep bottom  see if it brings up shavings.
 Once the cam lobe starts to wear off, there is often a thin fin of material left at original height, to one side of the rocker. Its because the rocker does not always cover the lobe..
 if you see that, grab yourself a drink....... cuz it aint gonna heal itself.

 Fwiw, I had one far worse than the pic, 200 miles from home, cut the frame, got some parts and fixed it.
a piece as small as 1/8 inch can block the oiling system., and kill your cam and rockers.. sometimes the cam will break in two.

[seanbarney41]

from what I have seen, usually the outermost cam bearing and journal on the side that is plugged, will eat itself fastest.  On mine, the cam was literally rattling around in a hole 1/4" too big within less than 5 miles.  The cylinder head had a palm sized pile of aluminum shavings and every cam lobe and rocker were blued and scored except for the ones furthest to the other side.

[754]

 when partially plugged they can go for months, mine did.,

[kingrabbit]

Hey I appreciate the input and sage advice guys.
So I did the Q Tip probe. Reached down around the valve springs as far as I could. No metal shavings or particles. I noted brown residue up in back on #4. Burnt oil or rusty oil. I sprayed some penetrating oil in there.
Is it possible to clear the oil passage without pulling the head? Where exactly are the oil openings that feed the valve train?

[bryanj]

Under the cam carriers so the engine is out and the cam out

[Jerry Rxman Griffin aka MuthaF'er]

Is it possible to clear the oil passage without pulling the head?

If you have a frame kit installed on your upper frame rails only, so you can remove the valve cover. The head can stay put but the rockers, cam, cam towers must come off. I'd get a second opinion from someone that knows what to look for before removing the engine.

The oil passage/jet (2 total) is under each of the cam towers. It directs oil into the cam towers and it sprays from the cam tower oiler opening holes. Cover your exhausts, remove #1 and #4 exhaust inspection caps, fire it up and rev it good one time. Maybe even have a second pair of hands so that you can observe with a flashlight while the other person revs it. Say, maybe, 5K or more.... not just a little.   

[kingrabbit]

No frame kit so I am going to try the ‘rev-er-up’ test. When you say cover the exhausts do you mean plug em? Like jam a potato in there?

[754]

 I think he means cover the pipes so oil does not hit them.
 if you are not getting valve clearances that are loosening, you likely don't have an oiling problem.

[kingrabbit]

I tried it. Pried my son away from gaming long enough to start n rev it to 5000 for a few seconds. Good spray out of #1. Nada on #4.

[evinrude7]

I tried it. Pried my son away from gaming long enough to start n rev it to 5000 for a few seconds. Good spray out of #1. Nada on #4.

is it dry in there on 4?

[scottly]

Don't run the motor anymore, although the damage may already be done. I have weldless frame kits on hand, should you decide to go that route..

[kingrabbit]

Evinrude I would not call it dry in there but clearly restricted. I noted as this problem progressed and I checked the valve clearances several times that the tappet covers were wet. More recently I sprayed penetrating oil in there with the feeble hope it would help clear the plugged orifice.
Scotty what does the frame kit go for?
I have another running bike and this one is offline til this gets sorted.

[evinrude7]

i'd pull the motor.

[Deltarider]

Is there any difference in oil supply when in: a) on the sidestand and b) on the main stand? Personally I never have my bike idling when parked on the sidestand.

[754]

 when you see the oil passage, and the restrictor jetm with the tiny holes you will understand why you can't clean it from the outside. it's 2 inches down thru the parts. be care full with disassembly,  very easy to blow those jets across the room..

[ekpent]

 This is what the little fella looks like .