I have restored a few other bikes but this is my first Yamaha. 
I am in Pensacola, Florida. 

I'll be first up lol & welcome from NZ. Look forward to pics of what you have & progress as you 'get into it'. Cheers.

Sorry  I forgot to up load the pic.I have had this bike in storage for about 10 years, ran the last time it was out. I am not sure of the year, I am thinking 77, the engine number is 300-052476, and the vin sticker is very faded so I haven't been able to read it yet. I am in need of a wiring digram once I confirm the year.   

 

  

Greetings from Tennessee  
 look in the tech library for vin info also maybe a service manual to download in the library I really like P Cola I used to go every year when they had the Mustang Nationals every year 

Hey thanks for the pics, good pics too. Think those still have points ignition so pretty reliable & points clean/scratch [through the window slot] often sorts no spark.
I guess the air filter hose has gone hard & needs replacing & also guessing the filter has turned to dust. Great little model those ones.
Black from the mag is the only wire related to spark. If there's a black/white it's only for earthing out the spark to stop the motor.

It's at least a 1979... You may have meant VIN starts with "3J0" and it's most likely a 1981 model.

Did they go square swinging arm on 125's i'm sure 175's did at some stage. Also the leading axle forks are a bit of a giveaway as to the year as early monoshock ones were straight axle forks, different tank too. Whatever year it is i doubt much changed in the motor of those good 6 speed models. Enjoy.

Think Mark is correct '81 model.
Morley, I don't think the US market had the square section swing arm, but they did have leading axle forks which we didn't get in the UK