SOHC.co.uk Forums > CB750
Is this master cylinder original or reproduction
andy120t:
My CB550 original one is a faded purple too..it looks far nicer than the replica ones. Patina!
Oddjob:
--- Quote from: Martin6 on May 26, 2023, 05:35:15 PM ---Could someone explain how the oil flows through the filter system / how it works?
--- End quote ---
Comes from the oil pump, which sucks it through the strainer in the oil pan or sump, the oil pump feeds the oil filter, it flows on the outside of the filter and strains through to the centre of the oil filter bolt which then feeds the crankshaft first which in turn feeds the conrods and the oil reducing valves which are fitted to the barrels before they go on, this then feeds the camshaft journals and then flows back down through gravity. The rest of the engine is mainly lubricated by a splash system, with all those moving parts inside the engine there is a lot of oil being thrown around. This is on the 500/550, the 750 has a completely different arrangement. The 550 also has a small oil pump in the gearbox but that's not really part of the oil system.
There is a relief valve fitted to the oil pump and another fitted to the oil filter bolt, the filter bolt one is one I've recently found to be sticking, I tested 5 bolts and only one worked as it should, one was jammed and the other 3 were sticking. This relief valve is just a small cup with a spring which forces it up inside the bolt, the spring is held in place by a small roll pin. To test the relief valve get a small piece of right angled metal and slide it into one of the holes right under the nut end of the bolt, you can see the relief valve up overing up the next layer of holes, press down on the cup and the holes should become exposed, it should then move back into place when you release the pressure on it. The idea is that if the oil filter blocks or collapses (which one of mine has in the past) the pressure of the oil will force the cup down, oil will now flow through the top holes and exit the next holes down, these holes will be inside the filter when it's in place. So it bypasses the filter and allows oil to go into the engine but of course it's now unfiltered oil so it's not a good idea to leave it like that.
That help?
robvangulik:
A picture says more than a thousand words? ;)
Martin6:
Thank you, I know it's not rocket science, but I'm struggling with how the bolt and filter are sealed, so that only filtered oil continued onwards. Plus how the pressure relief arrangement works. The picture helps. I know I don't need to know, just interested.
To check:
- The fixing bolt (with the holes in) screws into an engine supply 'gallery'. Does it have 2 different types of holes, one set for filtered oil and one for unfiltered (when pressure relief is required)? With the main supply holes in the bolt inside the filter, passing filtered oil into the motor via the gallery?
- The spring which requires the washer (which the bolt goes through), is it only there to push the oil filter hard enough to seal against the bolt on the flange outside that engine supply 'gallery', also ensuring the pressure relief mechanism section of the bolt is outside the filter?
- The pressure relief holes in that bolt. Are they are outside the filter (in the end section within that outer spring)? Does it work so, as flow gets restricted by an increasingly dirty filter, pressure builds in the oil filter housing until it pushes down the spring inside the bolt and unfiltered oil is forced through those pressure relief holes in the bolt and straight into the gallery?
Craizeehair:
--- Quote from: Oddjob on May 26, 2023, 06:16:34 PM ---
There is a relief valve fitted to the oil pump and another fitted to the oil filter bolt, the filter bolt one is one I've recently found to be sticking, I tested 5 bolts and only one worked as it should, one was jammed and the other 3 were sticking. This relief valve is just a small cup with a spring which forces it up inside the bolt, the spring is held in place by a small roll pin. To test the relief valve get a small piece of right angled metal and slide it into one of the holes right under the nut end of the bolt, you can see the relief valve up overing up the next layer of holes, press down on the cup and the holes should become exposed, it should then move back into place when you release the pressure on it. The idea is that if the oil filter blocks or collapses (which one of mine has in the past) the pressure of the oil will force the cup down, oil will now flow through the top holes and exit the next holes down, these holes will be inside the filter when it's in place. So it bypasses the filter and allows oil to go into the engine but of course it's now unfiltered oil so it's not a good idea to leave it like that.
That help?
--- End quote ---
Can these be brought back to life if they are sticking or is a replacement bolt?
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version