We will need lots more information than that! to wit:
Engine numbers--old one and new one. Generator make and size. Engine make and size.
Is the engine crank-shaft separate from the generator crank-shaft? Does it have a flexible coupling between the two shafts? Or, is it belt driven? Method of engine mounting?
We might not all be wizards here, thats why i ask for the preceding info. Everything, in all genres', is not the same. Is there anyone in your area that you could show those things to, that could be of more help to you?
Being able to visualize (see) the things will be very helpful, and quicker than here, i think. Rusty Jones

The engine I have is a 8 HP briggs on a 4000
watt generator , engine runs good but no out put
from the gen.
Model 190432

Type 1848 01

Code 81021321

The 6 month old Briggs 5500 watt gen has a bad
engine ,started with out putting oil in it. I
have not gone to look at it , just wondering if
it is worth a 60 mile round trip to look at it.
I now have some questions to ask the owner thanks
to Rusty Jones .

JMHO, find out the replacement cost of the exact engine that was toasted and plan on buying that and bolting it in place. You'll probably spend a lot more trying to make something fit together that was never meant to. Also, if you need a 4KW you can probably buy the compete genset new for less than the replacement engine Don't know why, but that seems to be the case. I attached a link to one at Amazon which is 3750W for just under $400. I also seem to recall that the governors for engines on generators have to be set up or adjusted differently. Something about they're either idling or at "full" throttle so they put out 60 cycles. Hopefully someone with more knowledge will weigh in on that.

Good luck,

Ev

Here is a link that might be useful: GenSet

Depends on price and fit? I would atleast go look at the gen. bussiness end if cheap enough. 5500W alot better than 4000. Both engines are briggs so the gen. set should accept you engine. I dought you can find 5500 watt for less than $700 bucks.

Generators don't necessarily all have the same crankshaft end. Some will be tapered, some will be standard.

Thanks for all the help,my engine has a standard
shaft and the gen requires a tapered shaft. It
wold not be a good buy if I have to buy a new
engine for it. I am going to see if I can find
what is wrong with my AG Tronic Inc 524009
generator. Thinking it may be the Capacitor
or Diode parts that I can check as the brushes
are ok and the windings look ok but will test
them when I get it apart.

This project started out as a way to pay
back a neighbor that gave me a air compressor
when mine started to knock he would not take
any $$ . I found a E3000 Homelite generator on
line for $75 , it started right up made power .
When I said I would take it I found that he had
the other gen that went with it. So I ended up with
2 good running 8 HP Briggs and 1 working gen. I will
deliver the gen to my neighbor that now lives 40
miles from me now after the holidays.If I get the
other gen working it will give me a spare , save
me trucking mine to my neighbors the next time
the power is out.

On the generator with now output. Have you tried "flashing the field"? Sometimes after long time storage they will lose their residual magnetisim. Pretty simple procedure if you Goggle "flashing a generator". I have had them come back to life by plugging a drill in and go from forward to reverse a couple of times. This method don't always work though.

Yes I tried "flashing the field" with a drill
yesterday, did not work this time.

I'll pass along something I learned but have never tried that may work. Use at your own risk!!!!

I watched a Gen repair man flash the field, his description not mine, years ago with a 9 volt battery. He said it was kind of dangerous because the battery could explode.

He disconnected the wires to the brushes and put some leads with alligator clips on the terminals. Connected the other end of one to the positive side of the bat and held the other lead to negative side of the bat for a few seconds, maybe 3 seconds at the most, probably less. He got a spark when he touched and released.

He said that it is very important that you determine which brush is positive and which is negative. He went by color code on the wires. He said most are red + black -, and that usually if there is a dark and light color wire the dark is + and the light is -. Such as black + and white -, ETC.

Be very careful if you try this, a warning from him. He put on a welding jacket and gloves, goggles, and face shield. told me to get way back, which I did!

The battery made a sound, kinda like a zing. I said O-s its gonna explode!

He hooked everything back up and it worked!

Before I can test run the generator I need a
capacitor , 1 diode but will replace both ,and
2 circuit breakers . What I found is that I have
1 fried diode ,the yellow wire that was connected
to it shows no sign of being hot but it melted the
solder connection. The capacitor leaked and needs to
be replaced.

See additional information on Sparks and Arcs...

http://www.smokstak.com/forum/showthread.php?t=99253

Sparky

Here is a link that might be useful: Sparks and Arcs

I joined that forum today ,posted my questions and
they were answered. Looks I need to rewind the stator
or replace it + the other parts it needs . I think
I now have a spare 8 HP Briggs for my other gen.I
may try to find where the bad connection or break
but I am not going to put $$$ into a generator that
might never work or be safe.

Thanks for all the information and help.I will
update this if I find anything.

Up date,I found a good 8 HP 4000 watt generator for
$80 on CL . I still have a spare 8 HP Briggs with a
tapered shaft , I have quit looking for a gen.
head for it. If our daughter and son-in-law lose
power they will have a gen. now. Interesting that
I could not find a good gen. head for what I found
a good running generator for.
The original generator exciter windings were bad
and I could not see where until I pulling up the
insulated connections.

Roflmfao !