The EX1000 does NOT have a 240v output. How are you checking this?

regulator?

I did dual test. I used a multitester. It read 240 volts. Also at the 12 volt battery terminals instead of a reading for 12 volts it read 24 volts.
It blew circuit breakers in my travel trailer and burnt the converter out also.
At the outlets, the multitester read 240 volts. I checked for an open ground but found none defective. The unit does not have a regulator as pharkus noted?
The electrical blueprint from the Honda site reveals the unit has a rectifier,ignition coil,engine switch and a tr/mg unit(whatever that is)

What does the frequency meter indicate? Does the engine speed sound normal?

The rpm's for some reason are running high. I was able to force the RPM's down but it has no effect on the 240 volt reading at the multitester at all.
This unit is not rated for 240 volts or 24 volts at the battery terminal. It is rated for 120 volts and 12 volt at the battery terminal originally.What happened for it to switch to 240 volts from both outlets? What part needs replacing?

Could be the regulator as mentioned but there is now way for us to know what part needs to be replaced.

My crystal ball is in the shop and the lady that does my clairvoyance is out of town.

Your set does not have a voltage regulator device other than the excitation winding and its associated capacitor. The voltage output of this type will increase with engine speed up to a point. Since yours is running too fast, voltage and hertz will be high.

The first "part that needs replacing" is whatever is causing the high engine speed. Without seeing the unit, diagnosis of that issue is not possible. Until you get the engine speed down to 3600 rpm where it should be, you cannot properly troubleshoot the generator portion.

My comments are based on some googling i just did, rather than personal experience with this model, so take 'em for what they're worth.

From what I gather, the EX1000 was redesigned in the last few of years and the newer ones use inverter technology. Any idea when this one was manufactured? (If so, the electrical blueprint you looked at might not match this particular generator.)

It it new? Does it have any history of performing "correctly"?

I wondered whether there could have been a factory setting error or parts mixup with one of the European versions of the EX1000 which are designed to produce 230V/50Hz.

An answer to Wayne's question about the frequency might prove interesting. (I noted that the EU1000, rated for 230V, is still supposed to produce 12VDC output, not 24V, but that could be a red herring.)

The unit is 20 years old. The best of honda generator ex1000. It has always worked at 120 volt and 12 volt battery charging capacity.I will check the electrixcal blueprint. This model has a set 120 volt output with two outlets. Each had put out 120 volts. The engine RPM for this unit has no bearing on the voltage, it is to remain at 120 volts.
Whatever occurred, it became 240 volts. The Hz remains at 50-60. So an electrical component is causing the electrical reading to be combined via the two outlets, hence 240 volts instead of 120 volts per outlet.
Thanks for your assistance and I will check the electrical blueprint for mistaken model year.

I need to add this unit does not have a voltage regulator. Apparently it has a stator in the windings. I dont think this would be the problem. The outlet on the generator was was plugged into a travel trailer plug. The travel trailer plug goes to a circuit breaker panel and to a converter. The converter determines whether to operate on 12 volt or 120 volt. When the honda 1000 was started it rpm'ed as if a heavy load was put on it and the converter in the travel trailer started smoking. Even though I shut the generator off immediately it must of received some damage from the overload of failure to determine operating at 12 volt or 120 volt.
With the absence of a voltage regulator it may be likely that the stator is at fault. Advice???

I have a hydraulic driven generator that the only real voltage regulation is the flow rate. If the flow is too high the voltage will start coming up but the difference between 120v and 130v is tremendous on generator actual rpm. I could not imagine the rpm difference to get 240 out of it via hydraulic flow without the whole unit flying apart. Best of luck on this one, please report back when you figure it out.

Generators in that size range are not generally worth the expense to repair a stator or rotor failure. Since you have eliminated engine speed as a possiblity (with your 60 Hz indication) there is not much left. If the capacitor has somehow increased significantly in value your V might go up, but I don't think it would reach 240V- and a more common failure mode for those caps is to lose value or fail completely, either of which will lower voltage. I must say that your instance will be the first capacitor excited set I have heard of where a winding failure resulted in a higher than normal voltage and otherwise normal operation. Winding failures usually result in smoke, engine loading and lower than normal voltage.

Thanks Wayne. I understand they did away with a voltage regulator and designed an internal stator. I dont know what regulates the volts. I am beginning to think the rectifier has a dual role in the ac/dc switching and that it somehow may be shorted in the middle. The carry over of ac/dc in the middle may result in dead 240/24 volts. Can I isolate the rectifier or do you know where I can purchase one?

The rectifier can probably be replaced with a Radio Shack 276-1185 bridge rectifier by using only 3 of the terminals (cost about $4). However, I don't think a bad rectifier would cause high voltage. The two units I had (Yamaha EF600, Honda ES3500) would still produce 120 volts AC with the rectifier completely removed. You might want to try that- just take it out and tape the wires up well. Looking at the linked manual, I think your unit should still make 120 v with the rectifier completely removed.

IMHO, there are 3 things that could cause high voltage (1)high engine speed, (2)your capacitor has drifted to a much higher value (3)a stator/rotor flaw.

You have eliminated high engine speed if you have 60Hz. Is the capacitor marked with a value? If so, do you have a way to check the actual capacitor (condenser) value? As I said before, if it is a stator/rotor problem, it would be the first time I have heard of a higher voltage as a result. Of course, there is a first time for everything.

Here is a link that might be useful: Manual ex1000

Thanks everyone. Problem solved. The governor was caught on a rubber grommet on the chasis. I removed the choke assembly and it was not in place correctly either. By adjusting the RPM now I can regulate the voltage. It is now fluctuating between 119-121. Case solved. Thanks again

Wow, that sucker must have really been racing to double the voltage. You're not putting rocket fuel in it, are you? Just kidding.

Good on ya for solving your problem and thanks for checking back in with your results. For me, it's an interesting bit of "experience" gained vicariously--without having to burn out anything of my own. Too bad about the converter.

It must run at a relatively low rpm to have enough range to hit 220! I guess now you know if you want 220volts just make a pigtail plug over to a 220 outlet... oh never mind that! glad you got it fixed!!

I have the same honda ex 1000, when i put the ac Circuit breaker ( on the generator) to the on position with no load connected generator looses rpm and then the circuit breaker trips again . Any help please ? BTW do you have the service manual of this generator?