cam noise

Hello, folks. I'm trying to diagnose a potential problem with my motor, and the SEARCH function has been helpful, but I haven't found anything that directly matches my symptoms.

The bike is a 1980 KZ1000ST (the same bike in the KZ1000ST Resuscitation thread in the Projects Forum). The bike is stock as a rock, with the exception of a K&N filter in the stock airbox.

The bike fires up and runs fine. Pulls like a team of mules. Spark plugs come out dry with a light grey/tan coating. The problem is that at idle, you can hear a "whirring" sound coming from the valve covers. Using a "screwdriver stethascope(SP?)", the sound in even between the front and rear cams, and louder on the right side. The cam chain appears normal. Most of the info I found using the search function referred to chain slap at idle from the cam chain. This is not a "rattle". This is a very distinct "whirring".

I switched to Shell Rotella oil, and this got rid of all other oddness from the motor, but the cam noise is still there, maybe it's more pronounced because all the other noises are gone? This morning I pulled the valve cover to check top-end lubrication and valve clearances. Valves are well within specs. One thing that I noticed when I pulled the valve covers was that oil was pooled up on exhaust valves #1 and #4 to the gasket surface. But the cams appear to be getting plenty of oil otherwise.

My question is, is this normal, or is this a problem? Remember this: Your only paranoid if you're wrong!

bls5050 wrote:

...1980 KZ1000ST..stock...K&N filter in the stock airbox...runs fine... at idle, you can hear a "whirring" sound coming from the valve covers...cam chain appears normal...not a "rattle"...very distinct "whirring".
...is this normal, or is this a problem?...

Am thinking cam chain sound has generally been more audible on the bicycle style cam chain as opposed to the later Hy-Vo design, even off the show room floor.

Often, a good close carb sync will noticeably reduce cam chain noise at idle rpm.
But the sync is perhaps more curative to rattle than whirring.

Good Fortune!

The two things that quieted the engine down the most were a carb synch with a Morgan Carbtune and switching to Rotella oil. I had originally synched the carbs with a cheappo guage settup that did not have numbers on the face, only hash marks and it didn't make much difference. I redid it when I recieved the Morgan setup, and the engine smoothed right out and produced noticably more power down low.

In a related matter, I just finished ripping the oil filter that just came out apart to read the filtering media. There was a slight amount of magnetic material, I assume from the rings reseating after sitting for more than fifteen years, but nothing out of the ordinary, so the motor isn't "making metal".

Did you closely inspect the top idler sprocket? I've seen a lot of bad ones on the KZ motors that come in. One was dam near ready to fall apart...

I took the valve cover off again and looked at the top idler sprocket. It seems like it has alot of play. It can move side-to-side maybe 1/8 inch, but it can move slightly up and down and back and forth on it's shaft, also. The FSM and the Clymers manual dont list wear specs on this part, so is this normal, or is this a possible culprit?

bls5050 wrote:

I took the valve cover off again and looked at the top idler sprocket. It seems like it has alot of play. It can move side-to-side maybe 1/8 inch, but it can move slightly up and down and back and forth on it's shaft, also. The FSM and the Clymers manual dont list wear specs on this part, so is this normal, or is this a possible culprit?

Perhaps sprocket needle bearing is shot, which might also explain the magnetic material found in oil filter.

Good Fortune!

At what mileage should the idler sprocket be changed?

Kapahulu wrote:

At what mileage should the idler sprocket be changed?

As the idler sprockets aren't part of scheduled maintenance, they would be changed when worn or damaged (same as cam chain). Permissible cam chain stretch is addressed in the FSM.

As with most engine components, conscientious periodic maintenance should enhance longevity.

Good Fortune!

If the sprocket has radial play (up and down) change it immediately. The rubber that the bearing is suspended in wears out more often than the bearing. The rubber gets very hard and brittle from exposure to heats and caustic chemicals in used oil.

I would suggest a new Liska with new pillow blocks

Some Z1E listings:
www.z1enterprises.com/detail.aspx?ID=2178
www.z1enterprises.com/detail.aspx?ID=332
www.z1enterprises.com/detail.aspx?ID=2177
www.z1enterprises.com/detail.aspx?ID=349

Good Fortune!

Thanks for the responses. You've pretty much sold me on a new Liska unit and aluminum pillow blocks, but this brings up a question: Can the Liska idler sprocket www.z1enterprises.com/detail.aspx?ID=2177 be retrofitted to my existing assembly? Or is that part just a replacement sprocket for this: www.z1enterprises.com/detail.aspx?ID=2178

I looked at the idler assembly, and it was not immediately apparent as to how to get the idler sprocket off of it's shaft. Maybe a press-in part?