kz900 strange engine noise

Very very nice work. Looks like you are an artist and craftsman.

Thank you all for your compliments, I really gave my best to manage it the way I see it in my vision.
In metter of this stupid sound, last night I had a revelation :ohmy:
Maybe my custom made headers can produce tacking sound. I wanted more ground clearance and made my headers to close to the engine. All of headers passing about 1" of the oil pan but there is one place that is questionable. That is drain oil bolt on oil filter cover. In that area 3rd header is passing just next that bolt.
When I seting exhaust headers I pull 3rd header with my hand to the right side of the engine to make more space between header and that bolt, and then I tighten flanges.
Tube remain fixed in that position, maybe 2mm (1/10") from that bolt.
But maybe is possible that, under the influence of heat and driving, header return to its natural position and products tacking sound beating at the bolt with every detonation in the 3rd cylinder!?
And when I lean bike on the right side, gravity move header from bolt.
Today I just checked this theory and saw that 3rd header is touching the bolt.

I didnt started the engine becouse ugly weather, rain, snow...but as soon as the weather calms down I will checked this. And pray

I would kill myself if that is cause of this problem :blink:

The frequency of the sound is exactly what I would expect for one revolution of the cam chain. It is too slow for the crankshaft, cams, clutch, etc. in my opinion. The old chain may have had a stiff link that would cause it to slap against one of the rollers, guides or even the crankcase.

From the parts shown, I presume that you installed a new cam chain. If so, and the noise is still there, then the mystery continues. Is there a chance that a thrust washer might be installed on the wrong side of a bearing, or something like that? Did this noise start suddenly? Was there anything that happened shortly before the noise started? Had the bike set up for a long time? How many kilometers on the engine? What caused the crack in the engine?

One thing for sure - You have an absolutely beautiful machine.

I showed what I found inside engine, rusted camchain, broken case, missing circlip on transmission shaft, bad transmission bearings...
and I replaced all of this with new oem parts:
-tsubaki endless camchain
-new piston circlips
-camchain ceter roler
-camchain front guide
-all new camchain roller dampers
-new inside and outside camchain tensioner
-all new transmission bearings
-all new transmission bearings bushings
-transmission output shaft
-new clutch basket bearing
-new clutch basket backplate springs (ape)
-new starter clutch bearing
-complete new starter clutch
-all new oil seals
-all new o-rings
.
.
.
-all other parts are inspected and seems ok, without any damage or exceeded tolerance.
-all 4 carbs show the same value on vacuum

everything is assembled by the book and everything works just fine. Transmission and clutch are more quieter then before and bike has enough power. That sound is just irritating but does not affect performance at all.

And yes, this sound came from nowhere and suddenly.

As for broken engine case, I assume that someone has put too long screw in the left engine mount and made crack into the case.

OldshoolHr as the clutch is not what belongs in that bike it would be fair to assume that it could of come from a bike thats seen a hard life and the clutch gear teeth are a bit more worn than the crank gear teeth in your motor and inturn giving you more clearance lash than should be and so when the motor is cold the oil is thicker and will dampen the noise you hear, but when hot it thins out and what your hearing is this extra clearance.

While sitting on the bike with motor hot put it in gear and hold the rear brake on and feed the clutch out just enough to put a slight load on the motor giving it just enough throttle to hold the revs in the ball/park that you say this happens and if the noise disappears you will have found your problem as its not uncommon to find old Z's with extra play in this area and if idle revs are set too low the motor will have this tuck tuck or cluck cluck noise you describe

Today I rotate this oil filter cover. Oil drain screw is now facing to the back of the engine. 3rd header is now free from contact with the screw.
I started the engine hoping I solve the problem. In first few minutes engine was working as it is now left the factory but :ohmy: after 5 minutes, clanking sound started again, gradually increasing. After 15min that was the only sound that I could hear. When I lean bike on the right side it stops. I think that this engine will be on the table, again. I just havent got any idea where to look anymore, in upper or in bottom side.

Leaning bike to the right places more oil on clutch and oil pump right....

Stethoscope oil pan ~ near the oil filter/pump!
Possibly a broken tooth on oil pump!

Oil pressures to spec at idle and higher RPM?

Just a thought...

OMR

Almost forgot... these are for the KZ900....

I have just assembled the bottom of engine and I didnt notice anything wierd inside. Thing that driving me crazy is that it would be logical that the sound occurs when the engine is cold, but here the situation is reversed. When engine is cold it sound almost like new.
The other strange thing is periodically intervals of this sound. At 1000rpm occurs about 100 times and it gives us some 10:1 ratio. Or 10 crankshaft rotation : 1 noisy clank.
The only ratio that is close to this is rotation of the camchain.
If crankshaft sprocket is 15 tooth and camchain is 122link it would be necessary to turn the crankshaft 8 times to camchain turned one full circle. Everything else is spinning faster than that Is it possible that my tensioner not working properly? Camchain is new endless tsubaki.
I already bought manual camchain tensioner and waiting to arrive but in meanwhile is it possible to set my automatic tensioner when engine is working? It is this type

"I already bought manual camchain tensioner and waiting to arrive but in meanwhile is it possible to set my automatic tensioner when engine is working?"

If you mean running, the answer is NO! Follow the manual.

Bill

I thought that first automatic tensioners did not have screw to secure the tensioner rod. They were constantly making pressure on the chain. Theoretically speaking, it is not possible to move tensioner rod to the back cos this tensioner has small retainer which does not allow the rod to move back. Is that true?

Perhaps so but the KZ900 does not have an automatic adjuster. This pic is not from a factory manual.

The factory manual says to align the timing marks, loosen the lock nut and then the bolt. The spring is supposed to take up the slack as soon as the bolt is loosened. Once the spring has taken up the slack you must then secure the tensioner in it's new location with the bolt and locknut.

I've not had much faith in the stock tensioners. I know what you're referring to about the automatic tensioners having a self locking function. Unfortunately, it's that function that sometimes slips and allows the chain to get so slack it can jump. As I said the KZ900 never had an automatic tensioner.

Hope this helps

Bill