Can a 1967 Honda CL90 run on unleaded gas?

Hi Everyone,
It just occurred to me that unleaded fuel didn't exist in 1967 when my
Honda CL90 was made. Is it ok to run on regular unleaded? Seems to run
just fine, is octane the only issue or do I need the lead for the
valves? I can get 100 low lead aviation fuel, but I can't imagine that
being any better. Any suggestions would be most welcome, it's an old
bike and I'd hate to be the one who kills it.

Steve.

 

Normally, I wouldn't worry with an old Jap bike, but 1967 *is* a bit
early, as you say. It's not the anti-knock, but the valve seats, as you
rightly say.

I'd be tempted to tip some of that additive in the tank every now and
again, on the basis that a CL90 uses so little fuel anyway the extra
cost will be minimal.

 

im not to shure if it requires it but u can allways go to ur bike shop
and buy a lead additive to mix in with ur gas

 

More ignorance spewed forth here from this old fart. The valve seat
(I've also heard valve guide wear also) recession issue is 'in theory'
and NOT in fact. I've never heard, even second hand, of a real case of
valve recession which could concievably be due to using unleaded gas in
an older engine.

Here, we're dealing with a Honda which has hardened valve seats anyway.
There is utterly nothing adverse which will occur to your engine using
modern unleaded gas of the correct octane rating.

-paul

 

I dont think there will be any issues... In the days of
leaded fuel, tetra-ethyl lead was used to improve the
anti-knock qualities of gas. The anti-knock quality is
numerically designated by the octane rating of the gas.
With the advent of the catalytic converter, the lead
additive would poison the converter, and so the switch
to unleaded was required. If the bike doesnt have a
catalytic converter (as in mine, a 2002 Honda CBR F4i,
non-CA), you can use leaded/unleaded, the only thing
that matters is that the Octane rating for the fuel be
above the minimum recommended by the manufacturer...

HTH,
irax.

 

Well, sorry to disillusion you, but when leaded was phased out, Shell
did some research here in the UK.

They took old A-series British Leyland engines (google for it) and did a
controlled experiment, running them on unleaded, and measuring valve
seat recession.

They discovered that "lead memory" meant that it actually lasted a
remarkably long time before significant valve seat damage was apparent -
IIRC, well over 30,000 miles. However, if the engine was used hard -
hammered and thrashed - then the wear curve became amazingly steep, and
damage was noticeable at as low as 5,000 miles.

In my then job as editor of a transport magazine, I was given the survey
for inclusion in the mag. Which I did.

It probably does. But it's so early, it might not. Almost all Jap bikes
made since about 197o have been designed for unleaded, but this one is
Beatles-era. And my posting was erring on the side of caution for that
reason.

Aren't you a little bit tired of making yourself come over as an
embittered, poisonous ignoramus?

We've had people like you before here, you know.... dear old Hoyt.

 

You *did* check exactly how old this thing is, didn't you?

It's a 1967 bike; scarcely bigger than a moped. Of course it doesn't
have a cat!

 

I have several thousand miles on my 69 CL90 without any damage or issues
while using unleaded. At that point in time, Honda was using some hardened
valves/seats so you should not have any problems. If you are concerned,
simply have the top end rebuilt with the newer valves and seats.

Carl