Did older bikes run on leaded or unleaded?

Question

I'm talking specifically a 78 Honda CX500 and/or an 82 Honda 450 Nighthawk. If they ran on leaded gas, how are they impacted by unleaded gas? Do I need the lead additive? Also, if you could please, rate these two bikes for me. The CX500 has 23K miles and is in "Good" shape according to NADA & KBB. The 450 has 5,545 miles and is "very Good" according to NADA and KBB.

I'm considering buying one of these bikes.

Answer 1

The Cx is the  in line V twin, water cooled with a drive shaft. If that is right it had 10.5 compression and needs premium or octane booster. I dont know about the 450. Personally I'd leave both of them with their previous owners and look for a newer bike.

Answer 2

It the CX500 has been looked after at all you should be able to get at least 100K out of it. They are a Motoguzzi copy and a nice city bike, but a bit light for a lot of highway riding.

The nighthawks were styled like baby sportsters. OK, I guess.

Again a fairly nice commuter bike for around town, but a bit light for highway runs.

I dont think they stood up as well as the CX did.

Parts and service might be easier to find if you need them though, and it only has 1/5 of the miles the CX has.

You won't know until you go and hear them and take them around the block once.

They are both used bikes and you have to balance what you like against your wallet too.

I would likely be tempted by the CX but I always did like Guzzis.

I can not imagine buying a used bike without riding it at least once.

-------

Leaded or unleaded won't matter. Lead was added to fuel to push the octane rating up without using the actual higher octane fraction from the refinery.

Try them on regular and if they knock under acceleration go to higher octane. You should not need any additives for them.

The idea that lead provided extra lubrication or anything like that was just marketing hype, like when they tell people today that high octane increases fuel mileage.

Octane is just to prevent preignition and knocking with high compression.

Neither of these are really high compression, though the CX should be close.

------------

Fiep and That Guy are giving you really good advice.

You can buy much newer used bikes fairly cheaply and have easy availability of parts and service.

The size you are looking at a lot of people buy as starters and trade up after a year or two.

Answer 3

The CX500 is sort of a minor classic.  A departure for Honda.  It got mixed reviews at the time but there are a surprising number of them still around, so they must have been a pretty good bike.  The 450 Nighthawk is more conventional, but the Nighthawk line was pretty good, though by some tastes a little dull.

The thing about a bike that old, even with low mileage, is that a lot of parts get old and need to be replaced.  Unless you want to rebuilt the bike as a 'classic', it will nickle and dime you to death.

I have a 1978 BMW which was made for leaded gas.  The lead in the gas does something to the exhaust valve seats, and if you use unleaded gas the exhaust valve seats burn away little by little.  You can get lead substitute.  Here in California it is designated 'for off-road use only', but it's the same stuff and I still use it.  About 1 floz. per tank.  Seems to work okay.

Answer 4

All Japanese street bikes sold in USA were designed to run unleaded fuel since 1977. Some need 93 octane but not the Honda's (87 oct)

Answer 5

Unleaded came into being in the early 70s, by 76 all machines were made for it

Answer 6

both good bikes- i rode a 450 nighthawk for years- its my bike of choice between the two- as far as lead additive, its nothing but snake oil- dont worry about it.  i have vintage machines dating back to the forties- never used lead additive, never will.

Answer 7

both did origionally run on leaded,

both will 'live' off unleaded without problems and without additives

what do you mean 'rate'?

why do you want one of those?

if you look for a vintage bike to collect, great

if you look for a cheap bike, don't do it