You've bought probably the nastiest Honda twin ever made.
A stroked version of the highly respected CB450, the 500 actually looks
quite nice in a classic sort of way, but for the UK market they decided
to paint it in chocolate brown or orange. With a brown seat. Ooh,
lovely.
Stroking the engine for the extra capacity endowed it with horrible
vibration characteristics. It's OK below 70: above that, it shakes like
an MS victim in an igloo. But that doesn't matter, because....
....the handling is so poor that you won't want to go over 70 anyway.
The engine was fitted with torsion bar valve springs. This *actually*
isn't a bad system, but it adds complexity (imagine a Ducati Desmo
set-up without closing rockers and you're nearly there) and has no
advantages. It also makes setting the valve clearances quite an exacting
job, and if you get it wrong (and many do), then the top end wears out
rapidly.
It also has an electric start system whose screws holding the starter
clutch vibrate out unless Loctited on a regular basis. This causes the
engine to seize as the starter drive locks up.
Best of all is the ignition system. Points, as normal for the era, but
so arranged that you cannot time each cylinder independently. You have
to set the timing for one pot (the left, from memory) and then adjust
the gap for the right by adjusting the gap. Appalling. You can *never*
get the timing spot on, and electronic ignition conversion is the only
answer.
The riding position is appalling, with high wide bars and a
sit-up-and-beg stance. You do a parachute act at speed, except you won't
go fast, for the reasons listed above. Flat bars make a big, big
difference and improve the handling by throwing more weigh on the
otherwise horribly light front end.
The camchain is one of the longest ever seen on a motorcycle, and is the
same size as that fitted to the 175 twin. Unless it's kept religiously
adjusted, it starts to flap, and that means replacement time.
Head gasket failure is not known. You can't lift the head with the
engine in the frame, so it's an engine-out job.
The carbs are those nasty old steel-piston Honda CVs. If the bike has
been standing, you'll never, ever get all the myriad passageways in them
unblocked from the stale petrol without ultrasonic cleaning. Don't even
bother trying the patent remedies.
The UK expert is the bloke behind this website:
http://www.thefang.co.ukBut the links don't seem to work any more!
Dave Silver in the UK has some spares, but I really wouldn't bother.
Give it to someone else.
I restored a CB500T a few years ago
http://www.chateau.murray.dsl.pipex....ges/CB500T.jpg
I wish I hadn't bothered. I just did it out of cussedness, really. It
was a thoroughly unpleasant motorcycle. I hated it. A friend kept
badgering me for it, and I told him he wouldn't like it, but he
insisted, and so for a small amount of money, I let him have it. He soon
hated it too.
Utter, utter crap bike. Don't believe anyone who says it's a classic. It
was crap when it was new, and now it's just old crap.