Model 71 engine

[stllplyswthcars]

I have a Model 71 that boasts a 7.5 HP Kohler engine. Lately my Cub burns more oil than fuel, so I plan on getting it rebuilt this Winter. Anyone know if it can be bored out to a larger HP? If so, what's a good source for the parts? Thanks, Scott

[wdeturck]

I have a Model 71 that boasts a 7.5 HP Kohler engine. Lately my Cub burns more oil than fuel, so I plan on getting it rebuilt this Winter. Anyone know if it can be bored out to a larger HP? If so, what's a good source for the parts? Thanks, Scott

The 71 came with a 7 HP K-161 and the replacement engine from a dealer is an 8 HP K-181 you might find used or just go to a 10 HP Kohler engine which is a little higher and you can shim up the grill & pedestal ith 3/4" square tubing

[Paul B]

If the engine in your 71 is the original engine, it has a bore of 2-7/8". Later K161's had a bore of 2-15/16" which is the same as the 8hp K181. Your engine can be bored to the 2-15/16 size and use the same piston as the 8 hp. The smaller bore is no longer available I don't believe, unless you find one on a dealers shelf someplace. Stens and Rotary make aftermarket replacements, but only in the larger size.

[stllplyswthcars]

Thanks for the the info gents. Those older horizontal Kohler engines are hard to find in Missouri. Are there other alternatives...like can one of the Kohlers off a newer Cub (late 1990's)) be easily fitted.

[Paul B]

No, not a bolt in by any means, although it has been said that "with enough welding rod, you can put anything in anything". The narrow width of the frame rails limits the easy bolt in swaps to the 7 to 12 hp K series engines. About anything else will require frame modifications, driveline, and wiring changes.

[wdeturck]

Paul; Thanks for the information about bores of the K-161 and the K-181. I had got a K-181 short block and not realizing the stroke is a 1/4" longer and makes the extra HP. I wanted to put the Spark Advance cam(Original's K-161 in the K-181 block) and the rod hit the camshaft so I had to use the later compression release cam shaft(it replaces the SA cam)

[JLazar]

Thats some interesring info on these bore sizes. I have a late 71. Most advice is to have the bore machined out to the next size bore. I like the advice about a upgrade to a K241. Hard to say what you would do with the hood brace clearing the k241 gas tank. But,...having an original equipment tractor is where I stand, but sometimes you got to have more power.

[Farmallgray]

Hood brace shouldn't be a problem because the 102 used the same hood as the 71.

[tractrs2nv]

Hood brace shouldn't be a problem because the 102 used the same hood as the 71.

Ditto, I was thinking the same thing about the square tubing? 71,102,122 & 123...same sheet metal...or is the hood brace different on the 122/123?

[jroy]

Hood brace shouldn't be a problem because the 102 used the same hood as the 71.

Ditto, I was thinking the same thing about the square tubing? 71,102,122 & 123...same sheet metal...or is the hood brace different on the 122/123?

They're exactly the same. A 10 or 12hp will bolt right in without any modifications. I swapped a small flywheel, bearing plate, and shroud onto my 14hp and dropped it into my 72.

[9803412]

I'm putting a Mag 12 in a 71 at the moment. As said you do need to cut the frame for the big flywheel.