Need help with wiring on lawn tractor

[AndrewFH]

I have a Sears 42" riding mower with a 16HP Briggs &
Stratton engine. Last fall it threw a rod and the
engine is not repairable.
I have gotten a 14.5 HP Briggs & Stratton engine and
am in the process of replacing the 16HP engine.
Unfortunately the guy I had look at the mower when it
first broke down removed and tore down the engine, but
did not put it back together or back on the mower (not
that I expected him to). He simply put all the parts
in a box and gave it to me. I can't get in touch with
him now (he's gone out of business) so can't go to him
with my question.
The 14.5 engine is an older model, although I am not
sure how old. I'll add both model numbers below so if
you need them they'll be there.
It seems to fit okay, although I am having to make
some minor mods (such as the muffler which will not
fit right on my frame). However, I am not certain of
the wiring and since I did not remove the old engine I
can't compare that.
The 14.5 engine has four wires on it (two sets of two
wires each with plugs on the ends). There is a black
and white set. The white wire attaches to something
under the carb (looks like an electronic part), there
is also a black wire attached to this part which is
grounded to the block. The black wire coming from the
plug seems to run up past the card and up under the
cover (perhaps to the flywheel area). The second wire
set is on the other side of the engine. It has a red
and black wire which run up under the cover. The other
end has a plug and there is a slight bulge in the red
wire just before the plug which I understand is a
diode (I think).
There are four wires coming from my key switch. There
is a red & orange set and a black & blue set. They
both end with plugs.
If I connect the plugs up just as they are wired (male
to female) I end up with:
1) red & orange plug from the key attached to the red
& black plug from the engine
2) blue & black plug from the ket attached to the
black & white plug from the engine.

There is also a thick red cable which I assume goes to
the starter.

Before I hook this up and give it a try, I wanted to
see if anyone could tell me if this was the correct
way it should be wired. Don't want to fry the
electrical system.
Anyone have any thoughts?

The old engine is a B&S 16HP model 311700 type 0132 E1
code 990910ZE
The repl. engine is a B&S 14.5HP model 287707 type
0227 01 code 9412224B

Thanks for any help.

[rockytopp]

You have a simple thing on hand.
the two wires that come from under the fly wheel with the plug (red and black)
is the alternator. it should plug to a matching set of wire's with the matching plug.
the ones on the carb, I am assuming that your old engine did not have this style carb. the ground wire is good the other wire is the hot wire and must be tied into the ignition side of the switch, it controls a needle that works with the switch, to prevent backfireing at the carb when the engine is shut off, also it must work or the engine will not run.
good luck.