When it comes to the RZ350, examples fall into three basic groups: Stone stock (the most rare), nicely modified models with tasty pipes and suspension, and rat bikes thrashed within an inch of their poor parallel twin lives and then tarted up for a quick sale (most common). While RZs are climbing in value overall, it is the stockers that have the most collectible value in the future. Lightly modified bikes are nice for riding, but stock will always be preferred in the collector domain.
The first thing that jumped out at me was the stock appearance of the exhaust system. The original RZ had a very complex system integrated into the stock chambers which included air injection and a very compact catalytic converter. These pipes were heavy and did not offer the performance of true expansion chambers, but they did allow for the RZ to be 50 state certified - for a short while anyway. Also in attendance on this particular bike is the charcoal canister and a evaporative system (more smog related items, primarily for California). These are parts that usually "accidentally" fall off during pre-ride prep. The inclusion of these two items goes a long way to helping verify this as a stock - and therefore collectable - RZ. The finish on the pipes has more shine than I recall, but that is not necessarily an issue. Your mileage may vary.
From the seller:
I have an excellent 1985 Yamaha RZ350 for sale. It is a low mile bike in beautiful condition. The body work is mint with a deep shine. The frame, motor and chambers look good with only a couple rub marks on the frame like front the seat etch. This bike is part of a collection and is only ridden around the neighborhood a few times a year to keep it running well. It runs, rides and shifts like it should. No known mechanical issues or leaks. It appears to have all original equipment like stock chambers, oil injection, center stand and tool kit. I run the oil injection and pre-mix in the tank. It smokes a bit like that but mostly at startup. Once warm it's minimal. Even with all the extra oil it never fouls plugs and always starts up. I am not an expert on originality so if something is important to you please ask. The only issues I know of are a clicking noise from the chain last time I rode it and the plastic around the ignition switch is missing. The chain I believe is from s sticky link from sitting. I sprayed a lot of lube to see if that fixes it.
This appears to be a nearly 30 year old motorcycle in original condition. The odo shows just under 13,000 miles, so I would anticipate some usual wear from the years and the road. The seller comes across to me as a forthright individual, and even notes that a pre-purchase inspection is an option if you are local (the bike is located in Florida). The best part: this bike is priced at a very realistic $6k USD BIN. There is also an auction, with the current bid just crossing $3k with reserve in place. That is very fair money for an RZ. If you like 'em stock, you'd better put a watch on this one. Check it out, and then let us know what you think.