Kohler CS12S Engine Repair

[Ulma Doctor]

I met a guy on craigslist to trade a pristine chopsaw for a honda motorcycle engine
i was getting the engine
he lives about 2 hours from me, so we made arrangements to meet at a convenient time and place for both of us.
that was about 2 weeks after initial contact. it worked out that we were going to be within 20 minutes of each other on a thursday
we exchanged gifts like at Christmas and began telling tall tales and kickin' tires
the subject came up of rebuilding engines and repairs and such.
he asked if i could take a look at a motor that he was looking for repair on
unknown condition of a motor could mean many things, but the guy seemed like a straight shooter.
i said, sure- let me know when we could meet up again like this and i'd be happy to help if i can.
the opportunity to meet was great the second time too, i just had to travel 25 minutes to meet up.
He brought the Kohler CS12S engine and a Yamaha 465 motorcycle engine too
he gave me the 465 engine just because! that was really cool of him!

The Kohler CS12S is used on the farm to power a mule-like vehicle, by his description
he said it was running great, then quit one day
he got the run around by a couple repair shops and the engine sat for a couple years

The Kohler CS12S is a 12hp , 357CC, normally aspirated , 4 stroke , overhead valve, gasoline powered engine produced in many configurations for many products
this particular unit has a variable speed transmission attached to the output and an electric only start system and is mounted to a cradle that is removeable from the mule




The engine rolled over, it didn't sound like there was anything clanging around- on the surface it didn't seem too bad.

i opened the valve cover to see if there was something a miss in the valvetrain
little did i know, my first guess was correct
this is what i saw when i removed the valve cover


the valve spring hit my shop flor as i removed the valve cover along with this....



this is the intake valve retainer cup, it is used in conjunction with the valve spring and a slotted shaped disc retainer to retain the valve under tension

here is video 1

even with the best of hopes, calamity can still be just around the corner!
more to come!!!!

 

[cathead]

Mike,

The older Kohler engines have my respect. I have three of the 16 horsepower ones and
they are very dependable. One I use on my wood cutting band saw and the other two are
on Wheel Horse C-16 mowers. With the built in alternator and electric start, they are
perfect for a sawmill, especially with the lumber prices these days. Another of my favorite
engines is the HondaGX 390, also available with alternator and electric start and a lot
lighter than the older Kohlers. Good luck on your CS12S repair. You probably already
have it running by now.

I'm watching the video and it looks like the CS12S has a starter-generator on it, interesting
for a newer looking engine.

 

[Cadillac]

That motor configuration is designed for utility carts and golf carts. There is the starter/generator below engine used for pedal start of the engine. When you press on accelerator it starts the engine and once the engine reaches 1800 rpm the starter internally switches to a generator and charges the vehicles battery. I’ve rebuilt ALOT of those engines and generators. Never have seen the spring cap pull through like that probably due to over revving the engine. If you need any parts or info on the engine don’t hesitate to ask. Looking at the exhaust pipe did that engine come out of a toro workman?

 

[Braeden P]

kohler engines are nice my friend had one that would not start he sprayed belt conditioner in the card and it started now the things starts first pull sweet engine

 

[Ulma Doctor]

Mike,

The older Kohler engines have my respect. I have three of the 16 horsepower ones and
they are very dependable. One I use on my wood cutting band saw and the other two are
on Wheel Horse C-16 mowers. With the built in alternator and electric start, they are
perfect for a sawmill, especially with the lumber prices these days. Another of my favorite
engines is the HondaGX 390, also available with alternator and electric start and a lot
lighter than the older Kohlers. Good luck on your CS12S repair. You probably already
have it running by now.

I'm watching the video and it looks like the CS12S has a starter-generator on it, interesting
for a newer looking engine.

I cut my teeth on Briggs & Stratton engines as a boy, went to their tech school for a week in the late 80's
i graduated to Onan and Kohler when i worked at a rental yard
the Kohlers didn't seem to scatter like the Onan Twins did
i created a wall of horrors from the Onan failures, they blew up dramatically when they let go
i got video 2 coming, you'll see some more of the issues this engine has....

That motor configuration is designed for utility carts and golf carts. There is the starter/generator below engine used for pedal start of the engine. When you press on accelerator it starts the engine and once the engine reaches 1800 rpm the starter internally switches to a generator and charges the vehicles battery. I’ve rebuilt ALOT of those engines and generators. Never have seen the spring cap pull through like that probably due to over revving the engine. If you need any parts or info on the engine don’t hesitate to ask. Looking at the exhaust pipe did that engine come out of a toro workman?

Thank you Cadillac, i wish i would have spoke to you before i ordered parts, but thanks for the offer of support!
i'll bang on your eardrums soon!!!
I have never seen a spring cup fracture like that
it appears that maybe it was hardened and not tempered correctly.
but that is a WAG on my part
i really don't know what it came out of, i should ask
he did say it was like a farm mule

kohler engines are nice my friend had one that would not start he sprayed belt conditioner in the card and it started now the things starts first pull sweet engine

Yes, the Kohlers are sweet engines.
they are well made and robust enough for service in many applications.

 

[cathead]

Mike,

My first engine as a child was a Briggs and Stratton engine out of a washing machine. It ran and ran and I took it apart
and put it back together and ran it some more. It was a great learning experience. I have a few old Briggs in my collection
of old engines. My favorite Briggs engines are a ZZ Briggs and a ZZ Briggs with a gear reduction on the crankshaft.
Also, in my collection are some Hit and Miss engines and a throttle governed engine or two and a few old diesels.
Refurbing old magnetos is an interesting skill to have so they have a HOT spark. It has mostly to do with timing the points
to open just at the time when the magnetic flux is the greatest which involved a bit of experimentation.

I can't wait for the next video! Hopefully I'm not hijacking your thread too much.

 

[Ulma Doctor]

Mike,

My first engine as a child was a Briggs and Stratton engine out of a washing machine. It ran and ran and I took it apart
and put it back together and ran it some more. It was a great learning experience. I have a few old Briggs in my collection
of old engines. My favorite Briggs engines are a ZZ Briggs and a ZZ Briggs with a gear reduction on the crankshaft.
Also, in my collection are some Hit and Miss engines and a throttle governed engine or two and a few old diesels.
Refurbing old magnetos is an interesting skill to have so they have a HOT spark. It has mostly to do with timing the points
to open just at the time when the magnetic flux is the greatest which involved a bit of experimentation.

I can't wait for the next video! Hopefully I'm not hijacking your thread too much.

i appreciate any information that you may have, it's never a hijack when you are sharing information!

 

[Ulma Doctor]

here is video 2

after a generous donation form @Cadillac , the project went forward at full steam!!!

thank you very much Cadillac!!!!

 

[Ulma Doctor]

The Kohler CS12S lives again !!!!
i didn't have adequate fuel supply, the engine didn't want to fire off at first.
i rigged up a fuel hose to a motorcycle tank set on top of a hand truck.
i laid the engine on my pickemuptruck's tailgate, precariously, upon a 2x4 to get the engine to somewhere near its normal plane of orientation
and hooked up a small gel cell 12v battery to kick er' over
here is the video of the first fire up, join me if you will...

Again, very special thanks to @Cadillac, for making this job a slam dunk!!!!

 

[Cadillac]

Gosh looks like you needed a third had for all the controls. That setup is for a pedal start operation. You’d press on the gas pedal which has a micro switch which would control a start solenoid to give the starter power. Once started the starter converts to a alternator internally.
Fuel is usually delivered by a diaphragm style operated of crankcase vacuum. Their should be a vacuum line coming off the top of engine behindish the carb.
Those engines vibrate till they get up to speed then smooth out. Never ran one on a bench always in vehicle. She runs like a top great job.
Your very welcome for the parts good to see them get put to use!