I have inherited a non running  71 yamaha At1b? Not sure how to tell between a b &c over the years ive been told it doesnt have spark but when talking with unc's brother he said reed valve
THINGS I am trying to find out frome this forum: What size fuel line do I need?  Is plain 2 storke oil okay to put in the oil reservoir? And where can I find a plug wire because I would like to change it the bike has been sitting for 20+ years and could use some love. Also looking for the connection tube that goes from the carb to the air cleaner box 
will add pictures when I go to pick it up this weekend
Thanks! 

Check VIN against tables. Reed valve would make it at least a 1972 unless someone put a newer top end on an older bike... it happens.

Okay Vin table says it's a 73 at3 in brigade blue definitely still blue chrome needs some love but everything is there except fuel lines and tube to the filter box

Greetings from Tennessee  

 from near Salisbury, UK.

You can still get fuel hose from Yamaha, although you might have to cut it to length - go to the Partzilla or CMSNL websites for part numbers.

Clauss Studios or KDI might have the connecting tube.

No need to change the plug wire, unless you can see that it is damaged.

Clean the faces of the points and replace the front and rear brake shoes (they are still available from Yamaha).

Welcome from NZ.
If it has 12 volt & electric start then it is possible to change the plug wire as is retained by a screw up fitting with a rubber insert on the 'wire-lead' inside the screw up fitting.
Also you'll need a battery with a bit of life in it to get spark, even to kick start it.
But i wouldn't go changing the lead without good reason.
If yours is 6 volt kick start only, the coil wire will be retained into the coil, so total replacement job. Once again the last thing i'd do without good reason.
Also if it 'is' 6volt magneto kick only, then no battery required to run it. But be careful revving as will blow the bulbs as battery balances & regulates the system--to a point.
Look forward to pics when you can.

Neat bikes, I have a 1970 AT1b. You can use 1/4" fuel line. I use the clear stuff from Lowes for initial testing. It's readily available and I like to see if the fuel is flowing properly but does get hard after some time.

You'll prob have to go through the carburetor if it's been sitting for a while.

If it has electric start you will need a 12N7-3B battery.

As mentioned Clauss Studios has the carb to airbox rubber. Talking about the air intake, check your air filter condition and there will more than likely be a mouse nest in the intake tract.

This is an amazing forum for your bike with a lot of knowledgeable (way more than me) people on here. 

Here she is! Got the carb off apart and soaking 
what's everyone using to get the rust out of the fuel tank there's still "gas" in thats gotta go but she turns over new battery is charging parts oon the way 

Many ways of cleaning rust from the tank - Evaporust, phosphoric acid, apple cider vinegar etc.

Could be good that it still has petrol in it as, as long as it isn't the awful modern stuff with ethanol in it, this might have prevented it rusting from the inside (at the bottom/seams).

The fuel that's in it is likely20+ years old hut definitely glad it's in there I haven't looked too far into the tank but I bet the rust is mostly on the Frame hump