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Questions about a possible bike purchase

Discussion in 'Mechanical & Technical' started by Grimm, Jun 15, 2014.

  1. Hey everyone,
    My wife and I are looking to purchase a 1982 CB750 Custom from a guy who bought it from the original owner (clean title and everything), but never put many miles on it (less than 40k miles). Everything seems stock except a few of pieces, the exhaust, tank, and a piece of the body that we don't know what to make of. In any case I have a couple of questions that I was hoping to get some answers to since both of us are pretty new to motorcycles.

    1) The speedometer shows a Max of 80 mph. I read that often the speedometer would max at 80 despite the bike being able to go much faster. Since my wife's current bike can easy do 80 and it's a 250, wouldn't it stand to reason that this bike can do a lot better than 80?

    2) The guy we're planning buying this from isn't very bike savvy, and bought the bike to go riding with a buddy (which never panned out), so he doesn't know a lot about the bike. The bike is listed as a custom, but on the side, the bike says "Sport" (not super sport). But this makes me wonder about the bike. Is this just a permutation of the custom series? All the customs I've looked at actually say "custom" on the side.

    Apologies in advance if this is remedial Q&A, but I'm finding a lot of mixed information on the web. We've asked the guy to give us the VIN, and we'll be looking the bike up with Honda tomorrow, but I thought I'd see if anyone on the forums had any information we could use.


    Last edited: Jun 15, 2014
  2. The VIN can give you the specifics on the bike model; once you look it up.

    As far as the rest; just keep in mind that the bike is over 30 years old, and many things made of rubber/plastic will have to be replaced if they haven't been replaced already. Also look into the fuel tank; as many older tanks have gotten water vapor inside them and then tend to rust. The carburetors may need some attention too, both because of aging rubber parts and sitting with bad fuel or water inside them.

    Yes, the bike should do well over 80mph!

    Good luck, and I hope that you enjoy the bike.


  3. Hate to say it but if you're new to bikes and are just looking for something to ride, this isn't the bike for you. As curveaddict said, even though it looks good (pic shows that), there's going to be lots and lots of dry rotted rubber parts and other things that are going to need attention. They won't all present themselves at the same time either so you'll get to a point where you're spending money on it more then riding it. The low miles isn't necessarily a good thing either. It just means it's been sitting for a really long time and degrading.

    I recommend moving on and looking for a newer, fuel injected bike that parts are more prevalent for.

    Also, I'm speaking from experience, personal and thru friends and family members.
  4. If you have some decent mechanical skills, then this bike is a steal. Those old CB's are bullet proof! I've had 2 over the years... a bit of carb cleanup some adjusting and I had daily riders that just ran and ran. Last one was a cb500 that I rode for 7 years and put over 25,000 mi on it before I wrecked it. I didn't even go through the carbs on that one. Filled the tank with diesel and let it run into the carbs to soak for about 2 weeks. Then drained out the diesel and filled it with gas and some sea-foam. Had to clean up the points and the points plate had been corroded. after that I ran 2 sets of tires off it and went through a chain and sprockets...never even changed the points, just filed and adjusted them every so often.
  5. Curve,
    Sorry, I had mistyped the mileage, it's around 40K. Still pretty good for a 30+ year bike.

    Great information. Thank you. We checked the electricals and everything seemed good although the tach cable needs replacing and the cables are about ready to get replaced as well, but we'll definitely have a look into the tank!


  6. This is great information, honestly. We've been looking for a bike that we can also get our hands dirty with,and we're getting it below blue book. I really appreciate the advice. Its going to help me mitigate these issues rather than be surprised by them.

  7. Go over to the UJM Forum - - and ask those guys. They're CB enthusiasts from the early days until now, and they know their stuff when it comes to these bikes.
  8. This is great news. We definitely want something with some legs on it. We were wanting a bike that we could tear apart if needs be, and are looking forward to some greasy hands. She and I both have some basic mechanical skills, and what we're lacking in, we can definitely get help with.

    Thanks to you and everyone for taking the time to respond to this post. It's greatly appreciated.

  9. Hi! I'm a proud owner of a 1981 cb750f SuperSport.

    The bike you're looking at is most likely a cb750c as you stated and the "Sport" logo is an aftermarket thing (You can buy stuff like that from auto-zone) and has nothing to do with the bike.

    The 85 mph speedo is something the government tried in the 70's-80's to crack down on speeding. A cb750 with stock gearing has a top speed of 124mph (supposidely).

    The 40k miles can be a lot or a little depending on how the bike was treated throughout those miles. And being as old as it is, it demands being worked on. Maintenance intervals are shorter than modern bikes.

    And be ready if you're looking to move up; these bikes are on the heavier side. I got mine from a bloke that tried to ride it as his first bike. He had it for 3 weeks, dropped it twice and got frustrated and got rid of it. It's not for beginners.


    I don't know everything there is to know about these, but I know more than some. If you'd like I can take a look at it for you and just give my $.02 if it's a good buy or not. PM me if you're interested.
  10. Much appreciated, PM sent!

  11. I had a Kawasaki 1000 that had an 85 Mph speedo crackup:

    As stated earlier, it was our government..

    "On September 1, 1979, in a regulation that also regulated speedometer and odometer accuracy, the National Highway Traffic Safety Administration (NHTSA) required speedometers to have special emphasis on the number 55 and a maximum speed of 85 mph (137 km/h). However, on October 22, 1981, NHTSA proposed eliminating speedometer and odometer rules because they were "unlikely to yield significant safety benefits" and "[a] highlighted '55' on a speedometer scale adds little to the information provided to the driver by a roadside speed limit sign"
  12. Hey everyone,
    I wanted to give a huge prop to Reid here. He took time out for my wife and I, who he's never met, to take a look at this bike before we bought it.

    We met for coffee just before, talked bikes a bit and he followed us over to the guys house and gave the bike a thorough examination as well as imparted some excellent advice on care and maintenance.

    It was really awesome getting to meet you. Thank you very much for helping us out. Looking forward to more talks about our CB750's. 8)

    Thanks again, Reid, from both of us!

    Grimm and Maitchbec
    Last edited: Jun 16, 2014
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