Motorcycle Repair: 1978 Hondamatic CB400, honda cbx1000, cheap tires

Question
I recently bought a 1978 Hondamatic CB400. I'm new to motorcycles and I had a few questions, as the bike I chose has little info about it on the net. Firstly, I want to change the oil. I've been told that with older bikes, motorcycle oil is preferable. Is that true, or do I just use regular 10w40? I also need to change the tires. Where could I find cheap tires on the net for my model bike, and around how much would it be for the pair. Would I need to check on anything else, as the bike has had many owners and been through potentially rough times? Also, The speedo does not work. I need to figure out how to replace or whether it is just the cable. Where could I find more info about the bike, or a manual of some sort, as I have no clue on instructions on changing the oil. Are there any hondamatic specific issues that I should watch out for?

Answer
First get on the net, possibly ebay, and get a manual.  9/10 times the speedo problem is a broken cable, so check the cable first.  Enjoy the bike.

Jan

In addition,  after you rated my answer...

First learn to read; note I only want to answer questions about Honda CBX1000 motorcycles.  I took pity on you and answered your question instead of throwing it into the open forum like I should have done.  Your rating just proves the fact I should have known better.  
Please do not ever ask me any other questions on any subject.  I am wasting my good time for nothing dealing with ungrateful idiots like yourself.  Get a clue.  Buy some cheap shitty Shinko tires and fall on your ass next time it rains.  Goodbye.