Honda Generator FAQ: EU6500is, Propane, Soft Starts, and Starter Testing

I'm the person who handles generator purchasing for our company, not a mechanic. Since 2020, I've ordered more than a dozen Honda generators for our crews and coordinated all the service calls afterward. Here are the questions that show up in my inbox again and again.

• What a "Honda 650 generator" really is
• Whether Honda builds a portable propane generator
• What "soft start contactor" means for a generator
• Spark plug 491055 and why you should be skeptical
• How to test a generator starter with a multimeter

What is the "Honda 650 generator"? Is it a 650-watt model?

If someone searches for "Honda 650 generator," they're almost always looking for the Honda EU6500is. It's a 6,500-watt inverter generator, not a 650-watt machine. The model name puts the rated wattage right there, but people drop the last zero when they talk about it. Easy mix-up.

According to Honda's published specs, the EU6500is delivers enough power for a portable setup on a construction trailer or a backup feed for a small office. It's not the same class as a little camping unit. If you're sizing it for a new job, write down 6,500 watts max and plan your loads from there.

I've made this mistake myself. I budgeted for what I thought was a 650-watt "quiet tailgate generator" and spent the next day explaining to my operations manager why we needed the bigger unit.

Does Honda make a Honda portable propane generator?

As of January 2025, Honda does not sell a factory portable propane generator in the U.S. The portable line runs on gasoline, and Honda's official site only lists gasoline models in that category.

That doesn't mean you can't run a Honda generator on propane. There are conversion kits, and some owners swear by them. But every project manager I've worked with says the same thing: don't buy a "Honda portable propane generator" listing without checking what's inside. It might be a gray-market import, a used gasoline model with an aftermarket kit, or a seller using loose wording.

I went back and forth on this exact decision for our remote sites. Propane stores better and doesn't go stale. Gasoline is easier for a crew that already carries fuel jugs. In the end we stayed with gasoline because our Honda generator service center could service the equipment without untangling a warranty dispute. That tradeoff is worth naming before you order.

What does a "soft start contactor" do for my Honda generator?

Here's the thing: "soft start contactor" isn't the usual term. A contactor is a relay. The device you need for an air conditioner is a soft starter. The part that often gets called a soft start contactor is the kit that limits the compressor's startup surge.

Why does that matter? Because generators are limited by surge, not just running watts. The EU6500is can run a lot of equipment once it's started, but an air conditioner can draw several times its running amperage in the first few seconds. A soft starter spreads that load out, so the generator doesn't trip on startup.

It took me a few years and one embarrassing call to a service center to understand that. I assumed a 6,500-watt generator could start any 3-ton AC unit. It couldn't—at least not without a soft starter. We put one in, and the next AC startup sounded quieter and didn't dim the office lights.

Do you need one? Only if you're powering something with a hard-start load. If you're running lights and tools, skip it. If you're ordering parts, ask your electrician for a soft starter, not just a contactor.

What is spark plug 491055, and should I put one in my Honda generator?

Look, 491055 is an NGK stock number, not a Honda part number. When you see it listed as a "Honda generator spark plug," the listing is pointing at a plug that NGK catalogs under that stock number. It might be right for your engine, and it might not.

I've learned never to assume a cross-reference is perfect. The correct plug for your Honda generator depends on the engine model and the published gap. If the owner's manual says use NGK BPR6ES with a .028-inch gap, using a different plug from a generic "491055" listing can cause a no-start, a rough idle, or worse.

Let me tell you a quick story. Everyone on our maintenance team said to buy plugs from the Honda parts counter. I saved about four dollars ordering a "universal" plug. The generator would start cold, then stumble under load. I spent half a morning chasing a fuel problem that was actually a spark plug gap problem. That one mistake convinced me: buy the exact plug, set the exact gap.

If you're searching for spark plug 491055, look it up for your specific engine, and check the manual before you install it. When in doubt, walk the model number into a Honda generator service center.

How do I test a starter with a multimeter on a Honda generator?

Before you touch the starter, test the battery. Set the multimeter to DC volts and check the battery terminals. A healthy 12-volt battery should read around 12.6 volts. If it's below 12.4 after a full charge, the battery may be the whole problem. I've had people tell me their starter was dead when it was just a battery that sat too long.

If the battery is good, disconnect the starter motor. Set the multimeter to ohms. Measure between the starter's large terminal and the motor case:

• Open line (OL or 1): no continuity. That points to a broken brush, open winding, or a bad connection.
• 0.0 ohms: a complete short. That usually means the winding is grounded.
• Some resistance: not automatically good. Compare it to a known good starter or the manual's value.

Next, check the wiring and the solenoid. If the solenoid clicks but the starter doesn't turn, test the voltage at the starter terminal while someone presses the start button. If you see 12 volts there but the motor doesn't spin, the starter itself probably needs rebuilding or replacement.

A bench test is the cleanest way: put the starter in a vise, connect a charged battery, and see if the gear jumps out and spins. I usually leave that step to our small-engine mechanic, because a starter can draw a lot of current. But if you know what you're doing, it'll tell you more than any ohms reading.

When the readings get confusing, stop guessing. A Honda generator service center can test the starter with proper equipment. It costs less than replacing a good part.