Hondatwins.net is a great place to get info on CB450s. There's some amazing members there. Steve is one of them, and he's literally a phone call away. There's also some great knowledge about them here. The only drawback to HondaTwins.net is that there's not very many people posting, and you sometimes have to sit on questions for days, if not indefinitely. Definitely post your questions here too because there's a few of us around here that can get you an answer faster. I get more responses/posts on my project thread on my twins here than on the Twins forum...figure that.
Like MoMo said, a full maintenance check/adjustment is in order. I would begin by this order:
1) Set your cam chain tension (there's a specific method used for that that Bill Lane and I can provide to you). It's different than the manual states.
2) Do your valve adjustments (there's some hints and tips that are necessary to make sure you have a perfect adjustment). Believe me that you want to do this adjustment only ONCE and not have to redo it by working too fast or without the knowledge. We can provide you with better information than the manual provides, so ask us when you're ready.
3) Run your compression check. Let us know your altitude, your gauge, and your method of testing compression. This will give us a simple glimpse of the health of the engine. The CB450's valve system was advanced for its time, but it's finicky and it wears when abused or neglected. I personally think it wears much faster than conventional valve systems. It needs more attention than most other Hondas, but owners didn't really care to adjust valves.
4) Proceed to ignition and check/adjust the timing, clean the points, service the plugs, check the cap resistance. Setting the points on Honda twins isn't as intuitive as you may think...took me awhile to "get it".
5) Go to the carbs last. The CB450s have awesome carbs...awesome as in....so simplistic. Bowls on both sides can be dropped without any tools in less than 20 seconds total. Easy to clean, easy to service.
Biggest gripe about the CB450 is shared with other Honda twins is the damned rear fuel connection on the tank. Requires you to drain the tank almost completely before pulling it. I've gotten lazy and I just pull off the connection and spill a half cup of fuel everywhere, but whatever. Point being, plan out your work so you are not pulling the fuel tank on and off. Service the bike with new cables so you don't have to pull the tank after you decide "hey, new cables would be nice after all".
Also, get in the habit of smelling your dipstick once in awhile to make sure you don't smell gas. Gas in your oil is destruction waiting to happen. I was lucky with my CB450K7 when it was ridden for a few minutes with gas in the oil (smoked like crazy). Luckily, damage was minimal and the engine remained strong but gathered some wear. I was extremely lucky. The lesson learned was to smell your oil once in awhile.
Your dad also deserves a motorcycle that is as easy on his back as possible. I recommend ditching the crappy stock rear shocks and getting sone Hagons.
Chain, sprockets, and a new set of tires are important safety considerations. The CB450 cannot just use "any" chain either....
Your bike looks good and simply needs many hours of arm sweat and steel wool cosmetically. Do you plan on a quick and dirty refurbishment or a full restoration? Lots of things I'm seeing need sandblasting. Frame does appear to have some severe rust (maybe just the camera) and I would be tempted to strip it all down and blast it and inspect.
August doesn't leave you much time to do a full blown restoration.
The CB450 is my favorite bike (no news to anyone around here). I have two so far, and I welcome any others I find. Proportionally, they are one of the most beautiful looking bikes Honda has ever made. They feel quick, and they are a blast to ride. They sound like large bored machine guns and a properly tuned CB450 can feel like a rocket ship. Your dad probably already knows this though!
My dad threw a fit when he was 18 when his father took him to the Honda shop back in 71. He wanted a CB750 SO BAD, but his father only allowed him to get the CB450..."It's big enough". My dad thought the CB450 was just a toy and he reluctantly bought it. That is until the next day he drove it 1500 miles and found it to be one of the most memorable bikes he has ever owned. He eventually wound up with a 750 SuperSport, but he's been thirsting for a CB450 twin due to their eloquence and simplicity that is unbeatable.
