Correct, Tyler. Your conclusion is valid. The cam chain, idler gear, and rubber tensioner wheel are all wear parts. They need scheduled inspection and maintenance. Upgrading the idler gear with a late production version, or a steel Liska Racing gear is certainly recommended.
Thanks for reporting the results of putting Liska timing gears in place of the rubber roller on the tensioner and an all steel Liska cam chain idler gear in your KZ650. The increased noise is normal for a roller chain running on all metal gears.
A roller chain is designed to be durable, not quiet. A Morse chain is designed to be "silent" but in my experience, are also reasonably durable. Just because the Morse chain is engineered to be "silent" does not mean that the gears are also "silent".
Your photo of the Ford double roller timing chain is interesting and illustrates the fact that a truly durable roller chain is double row. A good example is the Mercedes Benz M116 engine. A 3.8 liter, DOHC V8 which was initially manufactured with a single row roller cam chain. Disaster soon followed with rapid chain wear and then failure. Just like a KZ1300 with a chain tensioner problem, the result was pistons crashing into valves. Mercedes solution was a double row roller chain on later production, and retrofitting engines with the single row chain to a double row chain.
The most important item for preventing cam chain and cam train wear is using the correct oil and changing it at frequent intervals. Mercedes Benz engines that received lower grade/improper oil and/or lengthy oil change times, suffered drastic wear of the cam chains, cam followers, and cams. This is true of engines in general.
Proper oil and frequent oil/filter changes are critical to the longevity of the KZ1300 engine. The oil needs to meet 4 important criteria:
1. Motorcycle specific oil (no friction modifiers that cause clutch slippage).
2. Proper viscosity.
3. High ZDDP levels (1000 - 1200 ppm preferred)
4. Excellent HTHS (High Temperature High Shear) rating.
The KZ1300 engines were designed to use oil with at least 1000ppm of ZDDP, specifically to reduce wear on valve train components. The HTHS value is critical in preventing the oil molecules from being sheared and reducing viscosity. This is due to the fact that the engine and transmission share a common sump. The gears in the transmission can shear oils with a low HTHS value from what was once 50 weight viscosity at 212 degrees F, to 10 weight viscosity.
