Original

scorch · #1 03-10-2011, 09:45 AM

I have a technical question about my k161...wheres the best place to ask?

cubcadet100 · #2 03-10-2011, 09:48 AM

Your in the right place

#3 03-10-2011, 09:48 AM

Quote:

Originally Posted by cubcadet100

Your in the right place

scorch · #4 03-10-2011, 10:21 AM

Thank you. I am restoring an original, and was going to have the 7hp bored out slightly. I took the block over and they measured it at 2.878. Stock 2 7/8 bore = 2.875 - the motor was smoking a little prior to disassembly, but only when warm. Is it really worth the bore job? Should I just put a new set of rings and call it good? Thank you for your time.

cubcadet100 · #5 03-10-2011, 10:56 AM

Sounds like the bore is pretty close to std. If it were mine i would hone it and put a new set of rings in it, your smoke when warm was probably caused by weak rings (thats my opinion im sure there are others that wont agree lol) Im currently restoring an original too and im going to just rering and seal my 7hp but my engine was clean as a pin when i took it apart

Methos · #6 03-10-2011, 11:26 AM

Quote:

Originally Posted by scorch

Thank you. I am restoring an original, and was going to have the 7hp bored out slightly. I took the block over and they measured it at 2.878. Stock 2 7/8 bore = 2.875 - the motor was smoking a little prior to disassembly, but only when warm. Is it really worth the bore job? Should I just put a new set of rings and call it good? Thank you for your time.

I would have it bored out. Have the machine shop check the crank. If there is wear on the crank when you hone it and put new rings in it the rod could start knocking. I'd have the valves checked as well. While your doing it do it at once and get it over with. It will be money well spent.

scorch · #7 03-10-2011, 11:58 AM

Thanks for the info - the engine was also very clean inside, little wear. They did check the crank for me, and said it was within limits. I did have the valve seats done, and have new valves for it as the exhaust valve was a little fried. Trying to get this done for out cub cadet dealer. It will look nice in the showroom for the 50th this summer. Again, thanks for the help.

scorch · #8 03-10-2011, 06:09 PM

wow - tough parts to find...and expensive.

Merk · #9 03-10-2011, 08:13 PM

If you don't have a Kohler service manual get one. One can be downloaded free from this site or Kohler's website. The cylinder wall should be measure in 6 different areas so you know if there is any tapper in the cylinder. By time you hone the cylinder you will be close to .010 oversize rings which requires a new piston.

K161 motors had 2 different bore sizes. One was 2.875 diameter better known as small bore and the had a 2.938 diameter bore better known as large bore. This was tha same bore size as the K181 motors(8 hp).
Kohler doesn't have a .010 oversize piston. Most will bore the cylinder to 2.938 which is the same as a K181 motor. Another option is checking with Stens. They had a small bore piston.

The crank should be check for out of roundness. Kohler manual wants you to check crank diameter in 6 places. You can have crank journal undersized ..010 if the crank is out of spec. The connecting rod needs replace as Bill suggest. Other items that need replace are governor gear if it is plastic, govnor arm, head bolts, crank seals and gaskets.

Expect to spend $300 to $500 or more to rebuild the motor the right way. The cost will vary on how much you do. I would stay away from the auction sites kits. Their quality isn't that good.

The motor in my 70 is a small bore Kohler K161. It was bored to accept a 2.937 (large bore) piston. I haven't had any problems with it.