Top Cam Idler

650ed wrote: I thought they were there for damping since the parts catalogue calls them "DAMPER, guide sprocket." Ed

Think they call it that coz they couldn't think of another name for it.
To dampen a part it needs to be isolated from the adjoining components by an isolating substance (like the top idlers rubber block sandwich).
The idler shafts sit directly in the barrel casting so the little rubber block AND its position in relation to the direction of force from the camchain form no damping effect.
To have any slight damping use the rubber block would have to be exactly opposite the direction of force from the camchain.

Makes sense to me; thanks for the explanation. Ed

Straight from Kawasaki in May 6 1977:

SUBJECT:
CAM CHAIN IDLER SHAFT MODIFICATION.

To make the KZ650 engine even quieter, the cam chain idler sprocket shafts and the idler roller shaft have been modified to include rubber dampers.

DEALER ACTION:
USE NEW PARTS.

In some cases, the old shaft causes a rattling sound. The noise causes no damage, but if the customer complains of the noise, the new shafts and dampers may eliminate it.

RonKZ650 wrote: Straight from Kawasaki in May 6 1977:

SUBJECT:
CAM CHAIN IDLER SHAFT MODIFICATION.

To make the KZ650 engine even quieter, the cam chain idler sprocket shafts and the idler roller shaft have been modified to include rubber dampers.

DEALER ACTION:
USE NEW PARTS.

In some cases, the old shaft causes a rattling sound. The noise causes no damage, but if the customer complains of the noise, the new shafts and dampers may eliminate it.

The loose shafts rattled and rotated so they fitted the rubber blocks .
The blocks stop the rattle by stopping the shafts moving.
The most accurate they should call them is quitening blocks, noise dampening blocks will do but they are not there to dampen or cushion the idler sprockets which was the crux of the initial disscusion.
Also don't know why they went with the the "un-damped" shafts in the first place as it had been a proven solution since 72 with the 900.
Maybe a new cheapskate designer who thought he knew better and was the proved wrong :laugh:

RonKZ650 wrote: Straight from Kawasaki in May 6 1977:

SUBJECT:
CAM CHAIN IDLER SHAFT MODIFICATION.

To make the KZ650 engine even quieter, the cam chain idler sprocket shafts and the idler roller shaft have been modified to include rubber dampers.

DEALER ACTION:
USE NEW PARTS.

In some cases, the old shaft causes a rattling sound. The noise causes no damage, but if the customer complains of the noise, the new shafts and dampers may eliminate it.

Ron,
Do you know of any documentation that states which engine number (or date) started using the new type shafts & dampers? My KZ650-B1 Parts Catalogue dated June 25, 1976 shows the type without the rubber dampers and my KZ650-C1 Exclusive Part List dated January 31, 1977 shows the type with the rubber dampers. Other than that I don't have anything that narrows down when the change took place. Thanks, Ed

650ed wrote:

RonKZ650 wrote: Ron,
Do you know of any documentation that states which engine number (or date) started using the new type shafts & dampers? My KZ650-B1 Parts Catalogue dated June 25, 1976 shows the type without the rubber dampers and my KZ650-C1 Exclusive Part List dated January 31, 1977 shows the type with the rubber dampers. Other than that I don't have anything that narrows down when the change took place. Thanks, Ed

They say the new idler shaft dampers were added at engine # KZ650BE019151

Thanks! My bike was built in January ’77 so I didn’t know which flavor it had. It has engine # KZ650BE024201 so now I know it has the rubber damper type (just in case I ever open it up to replace internals). Ed

RonKZ650 wrote: It's the rubber center that goes bad, the rest of it never causes trouble. Heat and time eat up the rubber. I doubt $0.02 worth of difference i you're running stock or 1075 kit. Miles is kind of hard to say. Engines run hotter in city riding even though less miles, rubber is gettin older every day. Time and heat combine. I have 80,000 miles on my KZ1000 and never touched the idlers. The KZ650 centers went bad at about 150,000 miles. All 3 of the idlers will go bad with enough heat and miles.

My friend has put around a hundred k on his so far. Engine runs like a loose vajayjay but it still runs. I'd have to say it depends a lot on just what kind of oil you run AND city vs highway. 1075 with .410 cams and ten k later plus the original 20 plus years, miles and mine were shot. He is a mechanic and swears by quality oil.

hey zed,
i been out in the shop and got some gears ready to press together. :evil:












thanks for the info zed

leon

Thats a crazy looking hammer.....

Can't wait!

it is a piston hammer.
it has installed a few thousand pistons :lol: .

leon