Piston
 

Getting parts off ebay. Had a 12hp block, lost it, while I still had it, I bid on a piston and crank. Won the piston and the crank, also won a 10hp block, can I get the 12hp piston in the 10hp block? What does it cost to get it bored out?
Thanks,
Mouse

neither piston, nor crank will swap. Sorry bud. Boring shouldn't cost much, but you'll want to get the new piston first.

I want to bore out the 10hp to = a 12hp, and use the 12hp piston.
Mouse

Can't do, A 10hp has a (roughly) 3.250" piston, the 12hp has a (roughly) 3.5" piston. That's 1/4"....unless you sleeve it....but I don't think you could remove that much material without makeing it paper thin....if it even has room to go 1/4".
Second, the strokes different, which means the piston height may be different...but I know the rods are different, so the height may be the same.....doesn't matter. The price of sleeving it is probably higher that buying a new piston.
We'll need someone else opinion here.

Well I guy can try can't he. If I buy that WH, could I possibly take that engine out and put it in the CC122?
Mouse

It's a kohler 10?, or 12?.....as a matter of fact I'm pretty sure WH used the same engines as cub. Read the k###.
I'd like that WH.....maybe I'll buy it off you so you recoupe your loss.

This info came from a Kohler Service Manual.

The bore diameter for a 10 horse motor is 3.251.
The bore diameter for a 12 horse motor is 3.375.

The stroke for a 10 horse motor is 2.875.
The stroke for a 12 horse motor is 3.250.

The 10 horse crank will work in a 12 horse power block. I wouldn't do it....not enough stroke. The 12 horse crank will not work in a 10 horse power block. The counterweights from a 12 horse motor will hit the bore in a 10 horse block when the crank rotates.

The last Kohler motor (K321-14 horse block) I had sleeved cost around $85. That was 3 years ago. Odds are it is around a $100 now.

Is the piston new?

if you order a stens rebuild kit it comes with a new piston! there about $100 when i get them... but its everything to put the motor together, minus the connecting rod, i always spring for the kohler connecting rod tho. i've never re-used a piston when doing a rebuilt either... but thats just me

I'd do the checking first. A block needs to be bored to match the piston....but, this is with car engines....I guess small engines are diff.
Probably less options in piston size.
What king of clearance do they run?
.010"

I do the checking before I buy any piston(s) for any motor-cars or a small motor. I try not remove anymore material from the cylinder wall(s) than I have to. To me this is a good practice to do to any motor. I don't have an unlimited budget to work with.

We're on the same page then.
I'm new to small engines...just making sure there's no real diff in building one...other than you say always replace the piston, AND rod. This is new to me. I ALWAYS resize my rods, and use ARP rod bolts (car engines)....unless I'm blueprinting, then I'll use two sets and resize to get matching and correct length rods. Did you say you always replace the crank too?

OK I found a piston, rod and rings all for under $100! I looked @ WH and found a Co. selling complete kits for kohler engines, not only does it come w/that stuff but it also has all the gaskets and a free tune up kit. Whoooohooooo. I now have everything comming to complete this tractor. Or so I think.
Thanks,
Mouse

Good for you.
A small engine can't be all that difficult to rebuild...it's only 1 cyl., and there's no lifters, timing chain, etc.
I can't wait to rebuild the 12hp for my 124.
Don't have another tractor to use, and my son won't move the stove wood with a wheelbarrow.
So it's gonna wait until spring atleast.

Hey gentelmen,
When/before you measure to see if ya need to bore, replace, what all do you guys measure.

I have 3 kohlers I'd like to go through, a twelve, and 2 sevens for the 123, 70, and "O". They "look" great
Or could you refrence me to the manual, I have about 2/3 of the kohler manual printed, lol

Neighbour has the tools for measurement
Jason

Check out sections 10 thru 12 in a Kohler Service Manual. It will give all the needed infomation on disassmbly, what and how to measure and reassembly.