thanks Bill, you are very helpful for the beginner like me. yup I will get a pressure gauge and see.

I checked the service manual of CB-1 and it says "oil pressure at oil pressure switch: 490kPa, 5kg/cm2, 71psi)" which is similar to what you advised 5 bar.

but I am curious because it doesn't mention what revs - seems it means 71psi pressure to make the light goes off at idle but not your advice 7000revs ??

Plan to drop the oil pan......
is it difficult to do that or just
remove the exhaust and unscrew the oil pan bolt, that's it?

So finally I was determined to drop the oil pan because I heard ticking sound from the head. And found the pick up screen was completely clogged by some papers. Most likely they came from the aged oil pan paper gasket. Relief value and oil pump are fine. Everything on my bike runs correctly now. Thanks for all of you who helped.

Here is the clogged screen.

http://postimg.org/image/42bx1vcrp
http://postimg.org/image/rbyz6gxut/

Could be helpful information if someone have an aged bike and it uses paper gasket.....and have low oil pressure

hi, nice to see your sorted.

Thanks bill...the only thing I am concerned is the ticking sound I heard ... Means there was some damages caused to camshaft and values? Though I don't hear it ticking anymore now..

yvescheung wrote:Thanks bill...the only thing I am concerned is the ticking sound I heard ... Means there was some damages caused to camshaft and values? Though I don't hear it ticking anymore now..

That could be down to the fact that the oil flow to the valves and cam followers has been increased since the filter was cleaned , it is the highest point in the oil system and could/would have been the first to suffer oil starvation

yep...hoping that didn't cause too much damage to the camshafts and valves...it's as normal as it should be and no strange sound from the head now...