Cracked piston k241

[tntatro 171]

Here's a deal that I couldn't pass up. It was a craigslist buy from a guy getting rid of this k241 with a cracked piston for $40. It also came with the PTO pulley, ignition coil, two carburetors with air filter housings (one looks like a new aftermarket) and the engine appears to be complete except the muffler. There are small miscellaneous parts missing but it's well worth the price.

 

He said it needs to be bored but I don't know if he meant cross hatched or bored out. Can anyone tell me how to figure out what it needs other than a piston? I've never rebuilt a Kohler engine before. It will be a while before I actually get to it but any tips or how to get started would be appreciated. He said it turned over but he couldn't figure out why it wouldn't start until he pulled the cylinder head. He replaced the engine and wasn't going to spend time on this one. The bore has light surface rust but no deep scoring. I got the impression that he knew it has value for parts but thinks it is not worth fixing. I'm not at all experienced with these engines but I'm thinking it can be revived and well worth the effort.

[RandyLittrell 3,877]

You will most likely need to have it bored completely rebuilt. Very seldom does the hone and rering deal work very well. Once you are done, you will have a motor that will last quite some time!

[tntatro 171]

14 minutes ago, RandyLittrell said:

You will most likely need to have it bored completely rebuilt.

Does re-boring require a machine shop? I may be able to rebuild it but I don't know anything about re-boring it. I know there are tools that can be purchased to hone a cylinder but what about boring one out? What is the average price on having a cylinder bored?

[tntatro 171]

When I buy a parts chainsaw to rebuild I take it apart and check the specifications and bearings and replace what needs to b replaced. Doing a full rebuild is expensive even for something as simple as a chainsaw. There must be ways to check a Kohler engine for what it needs rather than assuming that it needs to be re bored and completely rebuilt.

[Achto 27,570]

First off down load a Kohler manual, there are free ones on this site. The manual is crucial especially if you have never rebuilt a Kohler.  Before you buy any parts disassemble the engine, measure the bore or take it to a machine shop to have it measured. If it is out of specs ( size / out of round) it will need to be bored. A machine shop should be able to tell you how far they will have to bore it out to get it correct. Judging by your pic I'm almost positive that you will need to have it bored. Also measure or have the crank measured at the rod pin. If the crank is worn you may have to have the crank turned and go with an under sized rod. Once you have your measurements then you can order your parts. Take your piston with when you have your parts machined so that they have it to size the cylinder correctly.

 

Here is one source for rebuild kits. Kits go from $420 and under for OEM and $90 and under for aftermarket.

http://www.psep.biz/store/kohler_rebuild_kits.htm

[Howie 886]

The overbore is going to depend upon cylinder wear and to a degree the machine shop. At one time around here it seems like one didn't like to go .010 with a boring bar but if they use like a Sunnen CK 10 type machine it is very doable. I have opened my own to .010 over with what is called a rigid hone by starting at the bottom where it is still round an working to the top. Frequent checking with bore gave I required not for everyone though. Best left to the machinist though.

[tntatro 171]

Thanks a lot for the replies. Now I have a better idea of what I'm getting into. It looks like I'll probably have to find a good machine shop. This will likely be a winter project. I have a transmission that I want to work on as soon as I can and a bunch of summer projects. 

 

It looks like the cost can vary quite  bit. I was originally considering using aftermarket parts but after mowing with my 1973 8hp 4 speed a couple times I hate to put anything less than the best into it. I've never enjoyed mowing a lawn so much and it will mow areas that regular riding mowers couldn't go up and down easily and safely. I guess it will be a matter of budget.

[RandyLittrell 3,877]

11 hours ago, tntatro said:

Thanks a lot for the replies. Now I have a better idea of what I'm getting into. It looks like I'll probably have to find a good machine shop. This will likely be a winter project. I have a transmission that I want to work on as soon as I can and a bunch of summer projects. 

 

It looks like the cost can vary quite  bit. I was originally considering using aftermarket parts but after mowing with my 1973 8hp 4 speed a couple times I hate to put anything less than the best into it. I've never enjoyed mowing a lawn so much and it will mow areas that regular riding mowers couldn't go up and down easily and safely. I guess it will be a matter of budget.

 

 

I am lucky and have not had to rebuild one of my kohlers, but the going word is that the aftermarket is OK. I believe Stens is what most are using and if you take it to a machine shop, they can measure and advise on what it needs. Most shops will want to bore it before you buy parts, that way you get the correct piston. Sometimes it takes more to clean it up than what you think it will. I would have the rod machined for a bearing while your at it. And if it has plastic governor gears, get them too.

 

A machine shop will probably have a preference on what parts work and can help you with that. 

 

I work in a body shop and been doing autoglass for over 30 years. Aftermarket parts have come a long way since the early years, most parts are pretty good. 

 

 

 

 

 

Randy

[RandyLittrell 3,877]

@Achto is right as well, different shops like to do things differently. Some want to finish bore it to match the piston, others the other way. As long as they stand behind their work, it should be all good!!

 

 

 

 

 

 

Randy

[oldredrider 2,548]

Nowadays with the aftermarket pistons, ALWAYS have the machine shop tell you what size piston to buy. NEVER let a shop bore your cylinder without the piston. While the quality of the pistons is still good, sizing has lost a bit in the quality control department. Recently had one come in that was .0025 undersized from where it should be. Fortunately,  I have a top notch engine machinist who knows what he is doing and always relays to me anything out if spec. and compensates appropriately.

Do some homework and find a GOOD machine shop. It pays in the end. 

[tntatro 171]

There is a shop that rebuilds Kohler engines a couple hours drive from me. They are called Kustom Lawn and Garden. I don't know anything about them, just found them online but they sound pretty good. The website doesn't say they do re-boring though. They sell kits, parts and do rebuilding. I'm assuming they would do it. 

 

It's good ti know the aftermarket stuff is acceptable. It's unlikely I'll be able to afford original stuff from Kohler if I have to completely rebuild it. Aftermarket parts are the same with chainsaws, as long as the specifications are good then they generally will be fine. I think a lot of people have problems when they don't check the specifications and assume everything is good to run. I've got a piston before that wouldn't even fit in the bore.

[richmondred01 2,237]

I’ve been building these engines for 40 years.

Get it bored by a reputable machine shop. Chances are you will also need the crank ground.

PM me if you need the specs.

you want your cylinder to look like this

[richmondred01 2,237]

[tntatro 171]

Just giving an update on the K241. There is a good local machine shop in town and they bored the cylinder to .020" over, turned the crankshaft to .030" under and installed a bearing on a new rod and they also did the valve seats. I bought most of the parts from them and they were all aftermarket. It came out to about $330 I think. I also bought new valves off eBay and I think some other parts that I forget now. I probably had over $400 in it. It now has close to 70 hours on it and runs great. It is on a Wheel Horse with a mid mount grader blade and being used to smooth out a long gravel driveway. I used it to mow with for part of a season also.