Kohler engine rebuild progress and questions

Country-Boy

Member
Location
Central WI
I’ve been rebuilding my Kohler K161 7hp motor for my IH Cub Cadet 70. I’ve got it disassembled and painted. This is my first motor rebuild and my dad has only ever did one before many years ago. I have the ultimate standard sized rebuild kit from isavetractors. Some folks say I need should bore this and my dad thinks it’s fine and others say it’s 50/50. Do you guys think I need this bored? Did we do a bad job honing? My dad thinks the low spot is high enough that the piston won’t reach it, is that true? Any thoughts/help are greatly appreciated.
 

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If it were mine, if you don't have the tools to measure taper and out of roundness of the bore, I would take it to a machine shop and have it checked for that.
I don’t have the tools and am trying to do this on a budget even though it doesn’t seem like that since I bought all the other tools and the best of the best of rebuild kits. Maybe I’ll take it to a shop for measuring and an opinion.
 
I don’t have the tools and am trying to do this on a budget even though it doesn’t seem like that since I bought all the other tools and the best of the best of rebuild kits. Maybe I’ll take it to a shop for measuring and an opinion.
Do it once and do it right even though it may cost more now, it will save you time and money later.
 
Hello Country Boy, welcome to YT! I see a fair sized area that rusted away at the upper edge of the bore by the bolt hole in the upper right of your photo. Even the larger pit that is a little left of center between the two bolt holes. If the top piston ring comes above any of that your ring job is not going to last long. I agree with J H about doing it right the first time, that way it will serve you well a long time. Think how many times the rings pass by there when the engine is running 3600 rpm.
 
Hello Country Boy, welcome to YT! I see a fair sized area that rusted away at the upper edge of the bore by the bolt hole in the upper right of your photo. Even the larger pit that is a little left of center between the two bolt holes. If the top piston ring comes above any of that your ring job is not going to last long. I agree with J H about doing it right the first time, that way it will serve you well a long time. Think how many times the rings pass by there when the engine is running 3600 rpm.
Thank you. I am leaning towards taking it to a shop for at least an opinion, possibly boring. I know I should do it right the first time. My dad doesn’t think the rings will come past the bad spots tho…
 
no dought it will run that way with a set of rings, it does look like them pit are in the top ring travel. all that will happen with them pits is they will fill up with carbon. if pieces of that carbon gets in between the piston and sleeve its just like have metal in there chewing its way around. so depends ,if you want a good proper job i would bore it , and if no oversize piston available then it could be bored and make a sleeve the original size and press it in. be money money though. and with honing u want a nice cross hatch pattern better than shown. i know what my call is.
 
no dought it will run that way with a set of rings, it does look like them pit are in the top ring travel. all that will happen with them pits is they will fill up with carbon. if pieces of that carbon gets in between the piston and sleeve its just like have metal in there chewing its way around. so depends ,if you want a good proper job i would bore it , and if no oversize piston available then it could be bored and make a sleeve the original size and press it in. be money money though. and with honing u want a nice cross hatch pattern better than shown. i know what my call is.
How do I cross hatch better? I have the lisle tool with 3 stones. It’ sentimental plus I spent so much on the kit, maybe I should bore it.
 
You have enough money in the Ultimate kit already . Exchange your std piston for oversized the shop says you need. Have them bore and fit piston to whatever oversize required. I think you will be happier with results in the long run.
 
The Kohler k series engine is a very rebuildable engine. I have done many in the day. Yes that cylinder should be bored, a machine shop will tell how much oversize. You have not mentioned the crankshaft. I would always turn the crank .10 under and put a new matching rod in.
See if you can return the kit. The machine shop might have a good source for parts.
 
How do I cross hatch better? I have the lisle tool with 3 stones. It’ sentimental plus I spent so much on the kit, maybe I should bore it.
to get your 45 degree cross hatch you need proper pressure on the stones and proper up and down speed. this pattern is for the oil distribution on the cyl. walls. i cannot see your pattern in the photo unless it is due to the lighting. but anyhow it is not proper from what i can see. and yes a rebore in this case is best. then the piston would be honed to fit by the machinist. anybody can pull out a piston and stick it back in the bore, or almost anyone, but doing it properly is another thing also. plus having the proper tools is necessary also.
 
Can you explain the governor thing further. What is made of nylon? How hard is it to replace the governor?

Go to www kohlerengines.com and you can view and download the Owner's and Service Manuals for FREE and the Service Manual will answer the governor question and MORE.

It takes a little digging around to find the download links, if you don't find them I can post them when I get home to my laptop later this evening.
 
to get your 45 degree cross hatch you need proper pressure on the stones and proper up and down speed. this pattern is for the oil distribution on the cyl. walls. i cannot see your pattern in the photo unless it is due to the lighting. but anyhow it is not proper from what i can see. and yes a rebore in this case is best. then the piston would be honed to fit by the machinist. anybody can pull out a piston and stick it back in the bore, or almost anyone, but doing it properly is another thing also. plus having the proper tools is necessary also.
Okay. I knew why cross hatching is necessary and does. We did it pretty lightly IMO. Ok. It’s so hard to maintain a consistent up/down speed.
 
Can you explain the governor thing further. What is made of nylon? How hard is it to replace the governor?
Heres example of nylon failure in Cub cadet forum
I have nt read just, photos of possibly example of age failing
ill try to find more from Brian Miller site for you
 
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Heres example of nylon failure in Cub cadet forum
I have nt read just, photos of possibly example of age failing
ill try to find more from Brian Miller site for you
"Heres example of nylon failure in Cub cadet forum"

THAT one doesn't look some much like "nylon failure" as it does that someone previously installed the wrong governor retaining screw, putting bolt threads in contact with the rotating plastic gear.

The nylon part didn't have a chance!
 
Using the three-stone Lisle will not correct the bore, only restore some of the surface finish, not truly honing. OK if the bore is not worn badly. You could be OK if the pitting is only above the travel of the top ring. If cost is a major factor for you since you already have the kit, try it for a while. If the rings don't hold up you can always tear it down and rebore it. Good learning experience for you.
 

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