k161 and k181 difference

calcubman · Mar 5, 2013

what differences are there in the kohler k161 and the kohler k181? the bore is the same and the stroke is different,does the connecting rod make the storke longer or is it the crankshaft. my problem is i need a new connecting rod for my k161 in which is has the small bore 2-7/8, i want to bore it to a k181 std, and use the k181 connecting rod. any experts out there no?

Tom Arnold · Mar 6, 2013

Both the crank and con rod are different by 1/4". Yes the bore size is the same at 2.938 inches so I don't know how you can bore your engine out and end up with the same diameter as the larger displacement engine.

You say your bore measures 2 7/8 but that equals 2.875 inches, not the 2.938 inches shown in the Kohler K manual. Perhaps you are not using the correct tool to measure your bore.

Why not stick with the 7 HP engine by purchasing a new con rod and getting the crankshaft polished? i don't think that one more HP is going to make a huge difference for you. Take the bore to 10 thou oversize, do the valves, make sure the head and deck or dead flat. Install new valve guides and springs.

Parts to do this are readily available on e-Bay.

calcubman · Mar 6, 2013

i am working with a 1961 Cub Cadet Original with a Kohler K161 (small bore)
the k161 had a small bore (2.875) (prior to a certain spec# which mine falls under) and a large bore(2.938) mine is the small bore and is egg shaped, so a rebore is neccasary, i was told you cant get the K161 small bore piston /rings/.010 over /rod .010 under anymore so you have to bore to a k181 std.which is 2.938. i do have a good source for parts,i am going to do all valves, deck,head, etc. on brian miller garden tractor tips site, he stated that a k141 will need to be bored to a 2.938 because the oversize piston and rings are not available, so i would think a k161 is do-able on the boring to a 2.938. is that correct?

calcubman · Mar 6, 2013

it's not the 1 more horse power i am trying to get, its just the correct parts for the correct application.

dhermesc · Mar 6, 2013

This might help you out.

http://www.ebay.com/itm/7hp-K161-Kohler-engine-rebuild-std-010-020-or-030-piston-and-std-or-010-rod-/120972615100?pt=LH_DefaultDomain_0&hash=item1c2a879dbc

The rod can be bought .010 undersized. I would go with the larger bore and be done with it.

joe csuti · Mar 6, 2013

First thing to do is get spec# off each eng,then spend some time researching pn's for parts needed,goto link below & lookup your spec#'s for each eng,check to see if crank same pn & correct pn for rod(s).

The 161 uses at least three different pn for crank & only one pn rod,the 181 probably uses at least the same number/more pn for crank,in addition to useing two different style/type piston/rod sets(old style,newer mahle).First thing to do is check pn for crank to see if they match for each spec#,then check pn for rods,if rod pn's match buy a new rod,if they don't buy an old style rod/piston set or the newer mahle set.
kohler

calcubman · Mar 7, 2013

thanks for the info. i ordered the kit std piston & 10 under rod.

dhermesc · Mar 8, 2013

I've used that supplier on K321 and K301 engines - never let me down yet.

k161 and k181 difference

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