Topic: Low oil pressure and leak (CB750 F2 engine)

[754]

Did you check cylinder for flat ?
 Sounds like good chance the dowels may need trimming..
 When you say you add oil.. how much ? Like 1/2 -liter , or full liter ?
 How long does it take to get low ? Days ? Week ?........... and do you think it's burning any oil ? Or just leaking out ?
 

[Terry in Australia]

Yep, further to what Scott said, above, can you see oil spraying around inside the cam cover thru any of the tappet adjustment holes while the engine's running mate? If it looks "dry" you might have blocked oil jets into your head, which will cause major damage, I know, my first K1's cam, cam towers, pistons and cylinders were destroyed as a result of oil starvation to the head.

You won't see a river of oil (which is a good thing) but you should see droplets of oil bouncing around in there, and splashing out of the inspection cover hole in little droplets.

[mazingerzeca]

Thanks for the replies.
Yes, the test was performed whith the engine running, and there was no accumulation of oil on the head.
I didn't check the cylinder for flat, just the head.
About adding oil, about half a liter. It gets low when the engine is running, the level rises after a few minutes, and it gets lower overnight, which I've read that is the normal behaviour of these bikes, due to oil return to the sump overnight through the valves.
I'm pretty sure that is not burning oil, the engine was overhauled due to that, but I changed the valves, the guides for new bronze ones, the cylinders were rebored, new rings, and I don't find any sign of burning oil, no white smoke, no smell, no oil on the exhaust.
Terry, I see exactly what you describe thru the tappet holes, so I think that the oil on the head runs OK. I see the oil moving on the rocket arms like when you are beating an egg, to make an image.
I'm afraid that what happened is that the oil escapes through the head gasket, the level gets lower, add oil, escapes through the head and so on. I will have to check the head gasket. Fortunately, I installed the frame kit, which allows me to do this without taking the engine out of the frame.

[PeWe]

If this only about oil level in tank will decrease overnight but increase after running it.
-No problem. Many CB750 run like this.
- Just take bike for a ride, minimum 30 minutes. Check level, refill if not at top mark on stick.

-Problem if oil warning will flicker and you visually can see no oil down the tank. This is what I wrote about when letting bike idle on sidestand.