I have replaced pump several times with my CB750 on side stand. 2 times for priming it (again) due to air trapped inside.
(Last time due to I removed the spring , piston with rubber I replaced due to wet sumping, oil in tank leaked thru the pump when parked. Air entered when oil went out the short time it took to do the rubber swap. Had to remove pump and prime it in a container with oil.)
If stock 4-4, remove pipes for cyl 3-4.
I had to remove my 4-2-1 on my K6 completely since it cover the oil pan
I used my phone selfie cam to inspect the pump and everything else. Remove eventual gasket residues. A pain if a sealer has been used before with residues on gasket surface.
Honda stock gasket (light green) the best alternative I have tried.
Holes where they should and a have nice surface.
Oilpan can be removed several times without replacing the gasket. Same with other covers when using Honda gaskets
I was laying down on my back when I was installing the carefully primed pump. Then I saw how to fit it.
Priming:
You have to rotate the pump sprocket with the relieve valve open to let air bubbles out when priming. The big alu nut removed or at least almost off with spring and piston inside.
Stock spring better than eventual oil pump kit replacement spring. I got 70PSI when cold with shiny replacement spring when cold at idle. 80PSI with old stock.
Rotate sprocket with pump submerged in oil, cover one hole with finger. You'll feel how it will suck. If not, cover the other hole. Rotate in other direction and feel the underpressure.
If you can not feel this, pump has air and will not work. No oil pressure when running engine on starter without sparkplugs.
The 3 new o-rings and knock pins must sit. Easier to have some oil on them. You'll see which is best, knock pin sit in case or pump. O-rings are important. I did both....
The pump must go on absolutely parallel to engine to avoid damaged knock pins or alu scratched off.
There is a reason why I have ca 10 new knock pins as spare
Worst first time....
