Top Cam Idler

Question to the forum:

What is the life span of a top cam idler under normal conditions? (proper oil changes and maintance). Starting at "0" miles

1. Lets say KZ 1000 in stock trim

2. Lets say KZ 1000 1075 - .400 lift cams...jacked up abit?

Thanks, Spencer

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.

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I replaced the top one on my KZ650 at 44,000 miles. As Ron said, the rubber center weakened so there was more play than I was comfortable with. The other ones are original (now at 53,000 miles); if I ever pull the engine apart for other reasons I'll replace them too. The KZ1000 uses a different part number, so maybe they last longer. Ed

Those idler sprockets are all the same whether kz1000 or 650.
When the rubber goes have it replaced with alloy.
As long as the teeth are ok and you keep a check on the needle bearing which is replaceable they will virtually last forever.
This is the size of bearing they need. simplybearings.co.uk/shop/p92295/BA78ZOH...ch/product_info.html
And here's a pic of the modified idlers.

So the idlers in the 650's are the same as the 1000's? I got a few 650 motors sitting around with idlers in them.

Powerstroke_fan wrote: So the idlers in the 650's are the same as the 1000's? I got a few 650 motors sitting around with idlers in them.

Yes! they are all the same, Same 17 tooth, same chain pitch, same bearing, everything.
All identical.
Only Kawasaki's men in suits knows why they have different part numbers,But probably to deter people from scavenging newer motors instead of paying top dollar for new.

Zed1015, regarding modifications of existing cam idler sprockets with Aluminium centres.
You don't by chance have an engineering drawing of this bush. With the price of these sprockets over $100, that is a great idea. I was experimenting with the thought of epoxy filling the space where the rubber is vulcanised to the metal, doing one side at a time!
RegardZ.

Garn wrote: Zed1015, regarding modifications of existing cam idler sprockets with Aluminium centres.
You don't by chance have an engineering drawing of this bush. With the price of these sprockets over $100, that is a great idea. I was experimenting with the thought of epoxy filling the space where the rubber is vulcanised to the metal, doing one side at a time!
RegardZ.

A guy in St. Mary's Ohio has been converting these gears for 10 years or so....he was a Honda Mech for 30 plus years and drag raced KZ platform bikes forever.....

Garn wrote: Zed1015, regarding modifications of existing cam idler sprockets with Aluminium centres.
You don't by chance have an engineering drawing of this bush. With the price of these sprockets over $100, that is a great idea. I was experimenting with the thought of epoxy filling the space where the rubber is vulcanised to the metal, doing one side at a time!
RegardZ.

Not got any drawings as i just make them as and when i need some or if a customer wants some.
Easy to do though but there is a set procedure when making each one to make sure they run concentric.
Having a bunch of inserts made may not result in all of them running true.
With the original rubber center there is a certain amount of deflection and once the chain is tensioned the sprocket outers aren't running parallel with the bearing.
The Modified idlers need to run perfectly true to avoid fluctuating slack and tight camchain issues.

4TheKZ1000 wrote:

Garn wrote: Zed1015, regarding modifications of existing cam idler sprockets with Aluminium centres.
You don't by chance have an engineering drawing of this bush. With the price of these sprockets over $100, that is a great idea. I was experimenting with the thought of epoxy filling the space where the rubber is vulcanised to the metal, doing one side at a time!
RegardZ.

A guy in St. Mary's Ohio has been converting these gears for 10 years or so....he was a Honda Mech for 30 plus years and drag raced KZ platform bikes forever.....

Yep! been doing these since the early eighties.
Amazing how people come up with the same solutions and fixes to these problems.
Unless he copied me ??? :laugh:

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.

Not so. I've seen many with failed bearings.