This is from the site Bring a Trailer (https://bringatrailer.com/) ...
This 1988 Yamaha YX600 Radian is equipped with a 599cc DOHC 4-cylinder and a 6-speed transmission. The bike was purchased one month ago from the reported third owner, and the tires and battery were replaced last year under previous ownership. The selling dealer recently replaced the spark plugs and performed a mechanical inspection. Under 15k miles are shown, of which the seller has added approximately 50. This Radian is offered by the selling dealer at no reserve with the owner’s manual, a copy of the wiring diagram, and a clean Wisconsin title.
Designed using parts from existing Yamaha models, the Radian combined the frame of the Maxim 550 with a de-tuned version of the FJ600 engine. This example is finished in black and features a single gold pin-stripe on the fuel tank, with lighting and gauges sourced from the Fazer 700. The seller notes the battery was replaced within the last year.
The front end features dual slotted brake discs from the RZ350 with calipers sourced from the FJ600. Cast alloy wheels wear tires reportedly replaced within the last year.
Instrumentation is similar to that used on the Yamaha Fazer and consists of a 140-mph speedometer and a 12k-rpm tachometer with chrome housings. 15k miles are currently shown.
The 599cc DOHC 4-cylinder was factory rated at 66 horsepower and is coupled to a 6-speed transmission. Features include four 30mm carburetors and a chrome 4-into-2 exhaust. When acquired, the seller performed a mechanical inspection and replaced the spark plugs. Paint loss is also noted on the case and cylinder head. No service records are available, but the factory owner’s manual will be included. A walk-around video with the engine running is provided below.