I have a '74 CB450 that my son and I are working on as a project. We want to turn it into a little cafe racer. This will be a street bike and wanted to ask you guys with old CBs a few questions and get your recommendations. I have raced with WERA over the years and want a bike that is not a total turd on the street. I have never raced this era bike but want it to be fun. I have raced mostly '90s and semi-modern stuff. I have a GSXR 750 front end I am putting on the bike and plan on getting a new set of wheels made up. I am thinking 18" wheels. I do have a 2-1 exhaust, but not sure if it is a good choice. Clearance may be an issue. Motor only has a little over 2K miles on it. I am thinking about the Mikuni VM32 carbs. Bike sat in a barn since 1977. I want it to be a fun project for us. Any recommendations you guys can give me?
Ummm....don't? Get Steve976 to tune in here on (attempting) to race one. I raced against a couple of them that were stock-ish in the AHRMA Production Light class. Good bikes and fast enough when left alone. Steve's problems all stemmed from hot-rodding one. Should make a fun cafe.
I believe the problem with these is the torsion bar valve springs. When people do not know what they are doing adjusting the valves. It is very common for them to over extend the torsion bars and ruin them. The torsion bars are hard to come by. I know some of the honda guys do coil spring conversions and make killer power out of these engines. Sent from my SM-G930P using Tapatalk
Its a really cool motor. I love the torsion bar valve springs. I wish you the best of luck and it should make a quick bike. Keep it light, do some port work and vm32's and I bet she will get along great! Sent from my SM-G930P using Tapatalk
I have one that have raced over the years. If I had to do it again, I wouldn't. Unless you are planning doing a lot of work to it, it will burn the cams out probably in the first weekend. The stock oiling system will not push enough oil into the head to keep the cams alive. There are ways of getting around this, all expensive. My bike has the head converted from the torsion bars to a normal coil spring and larger valves. The transmission is weak and has problems with the selector. All of that being said, they are fun motorcycles on the track. I am currently working on mine to have it back out this year.
I ran a Drixton CB450 punched out to 500cc for 3 years. My mechanic and I converted the torsion bars to coils. After ruining about 6 sets of followers, we figured out how to add an oiling system to the head. Prior to that, I had to send a continuing supply of rockers to Mega Cam to get replated. The bike fairly reliable for a bit. The transmission became a problem and we had to get undercut gears otherwise there would be a lot of issues. All in all, I amount of work and issues were too much to overcome. Todd and Buff did well to keep at it. In the hayday of that bike, Todd and I had a toe to toe battle royal at Mosport that ended by a wheel at the line. In the end, there are better bikes to do battle with than the CB450 motor.