Can I use unleaded fuel in a 1974 Kawasaki?

You can install the hardened valves and seats that unleaded gasoline requires.

If you run unleaded in it and no instead O' lead in it eventually (could take years) you will burn up valves or valve seats, and the engine will first begin to loose compression and some power then will start to run rough, and eventually not run at all.

If it were me and you decide to have the engine rebuilt get the new valves and seats installed so you can run unleaded, in the mean time I would keep a bottle of the lead substitute on hand.

1974 Kawasaki 900

I'm pretty sure that your bike will still run.

There is something quirky about having lead in the gas, though - hence why the lead substitute is in the marketplace. I'd try and use the substitute when you fill up - but I think you should be okay with a tankful without it, every now and then.

You really have no choice as there is no leaded fuel anymore.

you should use the lead substitute unless you can come up with new valves and valve seats that are hardened for unleaded fuel use.

Even in 1974 it was hard to get "regular" - which is what it really was called back in the early days of unleaded gasoline.

You will be fine running today's unleaded fuel.

Your mileage will be a bit lower than the old days, but that would be due to the lower fuel content of the ethanol that's now added.

Minor, you may not even notice.

The largest fuel related problem would be the rubber components. (compatibity with ethanol)

I must say that even that was no problem with my '74 Honda.

What James said. Japanese motorcycles were built with hardened seats and valves. The EPA first banned leaded fuel in 1972 even though it was stuck in the courts for a while. Japanese manufacturers aren't like Detroit...if a regulation is LIKELY to happen in the near future they engineer for it immediately. The American way is to fight it in the courts and do it last minute.

As an example of how practive the Big 4 were...I have a 76 Goldwing that has some insane redundancies built into the wiring for the headlight simply because the requirement was being debated in US Congress when they were designing the bike, even though it never passed. I can blow all my fuses and bulbs and still have enough light to be seen and get home.

It's not an issue: No Japanese bikes from the 70's or later need leaded gas.

I have a 76 honda and I have run unleaded in it for years and it still runs good.

yes you can unless you were racing it, which wouldn't be a good idea on that bike actually without serious upgrades.