They were an aftermarket accessory, expensive and not really needed. They also came in chromed versions. The biggest issue with them was in getting the engine sprockets and wheel sprockets aligned, because these don't always match up in the stock configuration (see the chain notes in the FAQ). The K0 required notching of the chain cover at the engine to make it all fit together; I never installed one on a K1-later, so I don't know if yours is also notched. They appeared first in 1970, due to the reputation of the CB750 being "the $1695.00 chain breaker tool". I always thought of these kits as being like the guy who stuffed a sock into his tight jeans before riding the "strip" for the night....
They are heavy, adding a lot of unspring weight, and between the weight and the extra friction, consume several HP in the process before reaching the wheel.
The 530 chain can transmit over 100 HP continuously, if properly lubed. The 50 chain (and similar O-ring chains) can handle about 70 HP. The difference is in the pins inside the rollers that also connect the links together. Superior quality chains like the Diamond XL series can handle even more HP and torque. I've long used the Diamond XL100 (hard to find!), getting up to 20,000 miles on them, replacing at 1.5% chain stretch. Dyno tests in the 1970s were used to develop these chains for the motorcycle industry, specifically for the CB750 and the Kaw Blue Streak, both notorious chain breakers.
Serious drag racers avoided them for their weight and power loss...chopper 750s seemed to have lots of them!
