K 161 rebored
 

Hey All,

New to the forum and I am working on my 1964 70 Cadet that Dad bought new and used for 20+ years. It has a K161 engine and I need the block bored. The machine shop says they can bore it 0.10 oversize and I was wanting to find a good source for a new piston and rings.

I found one place here, http://www.petessmallengine.com/html/page_126.html but the 0.010 piston says it's for an 8 hp. K161 or K181.

Will this piston fit in my 7 hp K161? Also, will the existing rod still be usable?

Thanks,

I would definitely put a new rod back in it. That old rod has seen too many years of use. NAPA sells Kohler parts. I buy most all my stuff there.

There were 2 versions of the K161 one was the "large bore" and the other the "small bore". The large bore takes the same piston as the k181, the small bore has the same bore size as the K141...my 73 has a small bore, and its hard to find oversize pistons for the small bore version...I dont know the measurements off hand, but it has been discussed here before, so a search might yield some results. A common fix for the small bore situation is to simply get it bored out to the k161-181 large bore size and throw in a k181 piston. Have you measured your bore?

http://www.onlycubcadets.net/forum/s...ead.php?t=1854

http://www.onlycubcadets.net/forum/s...ead.php?t=9193

Jeff (teet)

The large bore is a 2.938

I think it's the large bore. The bore is at least 2.94.

Am I right in that the original spec is for 2.9380?

I think the bore was measured with a dial gauge at 2.94-something.

I'm going to the machine shop tomorrow. Should I get it bored out for a 0.10 oversize piston? Is the oversize piston supposed to be 2.9297 + 0.010?

I am looking at page 1.6 of the Kohler Engine Service manual.

THanks,

The Kohler K series service manual lists the maximum std bore diameter to be 2.941....so if your 2.94 "something" then your engine should be bored .010 over, and the corresponding piston/rings installed. Make sure you bring the new piston/rings with you so the machinist can fit them properly.

Jeff (teet)

The machine shop will have to have the new piston in order to bore the cylinder to the correct spec. They can't do it without it. They can correctly measure the bore with a cylinder bore gage and get the exact measurements and then see if it is in or out of factory specs. I would download the Kohler manual if you haven't yet. It has all the specs listed. I would also take the crank to the shop and let them mic the crankpin and then you will know if it needs to be turned or not.

EDIT: Teet is faster than I am.. LOL

Thanks for the advice. Where should I get the piston and rings?

Should the new governor be a replacement of the existing one? I've never taken one of these apart.

It should be a new replacement. Most are plastic and can lead to failure. It's the first thing in the motor and the last thing out of the motor. When I had my K301AQS motor rebuild a couple of weeks ago I paid the machine shop $30 to install the new governor, piston and rings, and set the valves for me. They also set the bearing end play. For $30 it was worth it to me. All I had to to do is button it up and install it back into the engine.

A good machine shop will be able to order all the parts for you and do all the machining plus give you some good tips. I would talk to the shop before they started work to make sure they know what they are talking about.

Thanks for the advice. Looks like I'll have to pull the cam to get to the governor. I'll see what the shop can do to make my life a little easier.

The crank bearing is still in the block and I have no way of getting it out. Will that pose a problem when they bore it? I kind of think it would.

Well, I have the cam and governor removed and taking it to the machine shop today. Should I also get a new governor shaft since I am replacing the governor?

The governor shaft should be ok. I would replace your points pin with a steel pin. Sounds like your ready for some machining work very soon! Looking forward to your updates!

The bearing needs to come out or it will get filled with chips and crap from the boring process, and for the low cost of the governor cross shaft, I would replace it and the brass nut to eliminate the common oil leak there, at the very least.

Thanks for the responses. Looks like I will be replacing the piston, rod, governor and shaft, points, condenser. The valves are getting the once over too. The shop guy said he would take care of the bearing.

Well, the cylinder was bored out to 0.010 over and the valves were done. The crankshaft measured good and was perfectly round. Should I replace the rod too?

If it were mine I would. Just good to know everything is new.

I agree with what Dwayne said. Nows the time to do it right so it will last.

Have another question.

The shop said that the crank pin was perfectly round so they did not turn it, but he said it was a bit on the small side....

If I get a new rod, will there be any problems with wear since the rod would be new but the crank is old? Should I go ahead and have the crank turned to 0.010 under? The other concern with using the old rod is that the wrist pin would not have the same wear on it and may cause problems.

Check with your machinist and see if the amount is still within kohler specs for a standard rod. If it is borderline, then I would have it turned .010 and get a rod to .010. If your putting a new piston in your will be getting a new wrist pin with it also.

Picked up the engine today and the machinist said a standard rod would be fine.

Time to order parts.

Hi,

i have the same Problem with my K 161 from my 1961 Original.

The Meas of the Bore is 2,8795=73,14mm. Is this the small bore Block?

The Rod Pin of the Crank have 1,182=30,02mm, and the Rod have 1,183=30,04mm.

I can get a Piston Ring Set, here in Europe with 73,025mm, and a 0.10 Rod, but not OEM from Kohler, thats Aftermarket Parts.

And i can get this, in USA,

http://cgi.ebay.com/Kohler-K161-engi...item20b7e72fa1

What shouldt i do, are the small and the large bored Blocks the same Cast Blocks, or have this different Measurements, in Cylinder Wall?

Did someone have a Solution for me?

thanks, mfg Georg,

P.S. we have a new Cub Cadet Owner here in Germany, a Friend of mine purchased a 123.

:Cub1::Cub1:

Hey there ich353s,

I'm not really sure about the specs as I am new to this kind of thing. Maybe the guys here can chime in.

Here are a couple of pictures of the engine after it came back from the shop

Looking great! Soon the fun begins!