Honda GX160 Frequency Issues

Hi Folks;
 
So I have a Honda GX160 Engine on my generator; recently I have had a lot of power tools die on me polishers etc.
I even have one Angle Grinder which wont even run on the generator but runs fine on manis voltage in my house.
 
So I connected up my multimeter to the Generators output; and I am reading on No Load of Output Voltage =230VAC with a Frequency = 42.45Hz
 
I then adjusted the throttle until my frequency reached 50Hz; this then resulted in a Output Voltage =305.1VAC.
 
 
So this voltage of 300Volts is problem; 230VAC equipment will fail at this level.
 
My question is how do I adjust the frequency only and not the voltage ? Is this possible?
Should I be looking at the Alternator and not the prime mover? I am thinking that the Hz and Volts are proportionate to each other
 
I have attached some photos of the above information and also the throttle screw that I adjusted.
 
 
 
Any help is greatly appreciated.
 
 
 
 

Thanks Roy; Im in Ireland so we operate at 230VAC Single Phase Live to Neutral @ 50Hz normally so I take it 3600RPM should be equal to 50Hz.
 
 
The alternator on the Generator is Belle 2000 Range.
 
I took off the front cover I can see a capacitor and thats about it.
 
 
Would it definetly have a AVR ?
 
Could it be burried up the Prime Mover End of the Altenator?
 
 I have attached some further images of the altenator.

Yes the Engine is a Honda GX160 and the altenator is a Belle 2000 Range.
 
Very little documentation available for the Belle stuff online.
 
Only think I cant find someway similiar is on the below link; which has no mention of a AVR in it but does show the capacitor P23.

 
In my understanding a Capacitor would smooth the voltage output; Could it be use for another puprpose? ie voltage regulation in some way?
 

Well a bit of an update I swapped the capapcitor with no luck.
 
Output voltage is 230VAC and frequency still sitting at 42Hz

3000 rpm would produce 50HZ. The capacitor indicates a brushless generator, it sounds like the rotor has gone south. If so the unit is likely not worth repairing.

The low frequency at the specified voltage suggests the rotor. Either way the unit is finished.