Topic: Cb400f cam chain ?

[soonerbillz]

So I got my bike all back together and it starts and runs great.
 But at around 5-5500 rpm the motor(sounds top end) makes a short screeching noise.
 If I go to 6k or drop to sub 5k it goes away.
 Also after warm up the the idle hangs high then slowly drops.
 Oh yeah.. the tach over 5500 rpm, the needle swings wild +/- 2-3k rpms. Below 550k its stable.
 Other than these things the bike runs perfect.
 Any advice it much appreciated !
 Thanks all.

[scottly]

Pull the tappet covers off and make sure oil is getting to the top end. The screeching sound may be the cam running dry, trying to seize.

[soonerbillz]

Pull the tappet covers off and make sure oil is getting to the top end. The screeching sound may be the cam running dry, trying to seize.

Should I see oil freely pumping to the cam like other engines I've seen?

[scottly]

First look to see if the cam is wet, on both sides of the engine.

[Mark1976]

First look to see if the cam is wet, on both sides of the engine.

+1

[Nurse Julie]

Pull the tappet covers off and make sure oil is getting to the top end. The screeching sound may be the cam running dry, trying to seize.

Should I see oil freely pumping to the cam like other engines I've seen?

The oil to the cam on the 400 comes out of 2 spray bars, take 2 end tappet caps off, hold a piece of tissue over the tappet hole and you should see small splatters of oil on the tissue.

[PeWe]

I had a similar sound from my CB750 just before 5000rpm.
I was sure the cam got no oil. Checked inside, OK.
It did not sound bad at lower revs so I searched Internet and found the explanation on a Kawasaki forum.

Inline fours resonance frequency was in that area.
One or 2 exhaust spigots not tightened. OK after tightening them.
This with 4-4 and stock spigots. Crank balanced so no internal issue.

So verify all bolts are tightened as they should.

I have also had a vibrating horn and other things hitting each other in that rev area.

Speedo and tacho can scream too, their cables included.

[Tim2005]

First look to see if the cam is wet, on both sides of the engine.

Agreed. And don't run the motor until you have checked this.

[soonerbillz]

Hey folks , sorry for dragging g my feet on responses.
 I did a thorough inspection of the cam, chain and adjusting system.
 The oil pump is working properly  and lubricating the cam correctly.
 The tappets did need a bit of adjustment which did quiet down the top end some.
 It turned his issue actually was caused buy the aftermarket header tubes vibrating at that rpm point.
 I tightened the collars as they were a little loose but that really didn't do much but in doing that I inadvertently hit the down pipes with my wrench and they made a tinny rattle. Further inspection showed that the pipes were very lightly touching at certain points. So I took a large hose clamp and put it around the pipes and tightened it.
 Walk! No more rattle.⁸
 So using a pry bar and a rag and some back and forth testing I was able to spread the individual pipes enough to stop the noise.