Looking for engine solutions for 701

[Sailman 1,299]

I scored a mostly original 701 last December and am just now getting around to working on it. Turning the engine over by hand it turns what would seem to be a full revolution then stops. Pulled the plug and no movement on the piston so sounds like broken rod, etc. Of course it was sold as "ran when we parked it".

I don't have the space or expertise to tackle a rebuild job like that.

Any chance there might be a good usable one at the BS? Anyone have a rebuilt K161 engine? What would it take to have someone rebuild mine?

I also have a 704 with a K161 with pull cord start that appears to have compression. Best option to get it running and move that to the 701?

Just trying to see what my options are short of selling it as is.

Open to all suggestions. Since many of you are at the BS maybe there is an option there.

Thanks.

[ri702bill 8,968]

That original K161 is somewhat of an orphan - a one year design. It did not come with an ACR - automatic compression release, therefore the double belts from the S/G. It also has a smaller bore, like the K161 in a 702. Standard size piston and ring sets are almost impossible to find. You COULD use a later K161-S and dress it as an original until yours is straightened out.

Your 704 has a K161-T; similar but with magneto ignition that would need to be changed to battery ignition..

[kpinnc 13,728]

2 hours ago, ri702bill said:

That original K161 is somewhat of an orphan - a one year design. It did not come with an ACR - automatic compression release,

 

Is the rod the same size as later versions with the ACR cam?

 

I have no dog in the race of course, but am curious. My 701 engine seems ok initially, though I haven't run it. Just curious if rebuilding one is any different than later versions internally other than the cam and bore.

 

Kinda wondering if it could be bored as a normal 161, and use an ACR cam. 

Edited June 22, 2023 by kpinnc

[oliver2-44 10,367]

I think The k161 can be bored to use a K181 oversize piston. But the crank is smaller diameter than a K181 crank.so you would need to find a k161 rod.  They show up on Ebay from time to time.   Send  @richmondred01 a message and discuss that with him.  He has many years of rebuilding engines and is in North Carolina, not close, but not terrible far considering how hard it is to find someone to work on these old engines

[ri702bill 8,968]

6 minutes ago, kpinnc said:

 

Is the rod the same size as later versions with the ACR cam?

 

I have no dog in the race of course, but am curious. My 701 engine seems ok initially, though I haven't run it. Just curious if rebuilding one is any different than later versions internally other than the cam and bore.

 

Kinda wondering if it could be bored as a normal 161, and use an ACR cam. 

Oliver types faster than I do - yes, two folks come to mind to answer your question  - with actual experience. @richmondred01 and @squonk have dealt with early K-161's before...

[Sailman 1,299]

Thanks for the response. I have reached out to @richmondred01 but he is not doing K161 anymore. I knew the 701 was a 1 off but I didn't anticipate the difficulty sourcing engine parts. Thought it was just a standard K161. Might have to just "frankenhorse" it I guess...or sell it to someone who has the connections, ability and desire to keep it original.

[oliver2-44 10,367]

Parts for k161's have been scarce in the past, but this Ebay seller has 0.010, 0.020, 0.030 undersize rods and oversize pistons for the K161. @richmondred01

https://www.ebay.com/itm/385400040543?hash=item59bba1ec5f:g:coQAAOSwww1j01d~&amdata=enc%3AAQAIAAABACIYirB%2BsAijK4IU951Oi%2FgmNXlqqaKTYPhJ453%2FMKRIZ0XwsVrT6cHe9LQNAJ7FbqJvYnpE8tGn2N8m9IAJ4vyfPygzKK0kMFbol6YDe6UEAe88UJtJUWwvBbBB%2F7dWczot8b9%2Bg1q9I9drU7sgfSZrCHFcVfoZzTFhbeSL%2BXK1zYCWMBThfUqgRNg%2FNmBuZXVDqxiN6upcMb83yL17CmP4igoGMC4yjfdhLuronOyQQQJ3SycG%2BG8t5qwJGJoNLEIOFbIfn%2FBrkgomZO16s9fMxKfqJfqzbHZfYxs3Z6ezec3eLBIUu7A9FL9hCfFfjkoBu4g%2FY1p5aSTqfxQsano%3D|tkp%3ABk9SR_jS0dmcYg

[WHX?? 50,716]

9 hours ago, kpinnc said:

have no dog in the race of course, but am curious.

Here too as I have a parts 701 161 I was hashing around rebuilding as a drop in replace for a spare for a 701, 702 or any tractor using one. 

My half @$$ed purist side says try and save it. 

I have been told small block innards are getting rare.

@Achto

[Achto 28,777]

I Save Tractors has kits for K161 engines.

https://isavetractors.com/ultimate-engine-rebuild-kit-for-kohler-k161-7hp/

 

 

[WHX?? 50,716]

Ther you have it @Sailman.

I save is usually a good guy to deal with too. 

Now to find a machine shop in your area that you can trust...That might be the kicker. 

[Jon Paulsen 291]

Rebuild it @WHX?? 

 

I see he even has a full gasket set for my opposed twin. That one is next on the list. 

Edited June 23, 2023 by Jon Paulsen

[rmaynard 15,915]

18 hours ago, kpinnc said:

Kinda wondering if it could be bored as a normal 161, and use an ACR cam. 

I did just that on my 701 K161. Bored to standard size, and fitted with an ACR cam from a K181. Works great.

[Sailman 1,299]

22 hours ago, Achto said:

I Save Tractors has kits for K161 engines.

https://isavetractors.com/ultimate-engine-rebuild-kit-for-kohler-k161-7hp/

 

 

I have used Norman for carb kits, gaskets, etc so that's a great source. Now I would prefer to rebuild but need some help getting it done. I assume first thing is to pull it apart to see whats broken and what can be fixed. Then assuming block and crank are good need to measure cylinder to determine piston size? I understand oversized piston (.010, .020) if cylinder is worn but how does one determine "undersize" or standard rod?

[Sailman 1,299]

14 hours ago, rmaynard said:

I did just that on my 701 K161. Bored to standard size, and fitted with an ACR cam from a K181. Works great.

 

What would be the purpose of an ACR cam from a K 181? Would the cam that's in the current motor work if its not damaged?

[Achto 28,777]

3 minutes ago, Sailman said:

I understand oversized piston (.010, .020) if cylinder is worn but how does one determine "undersize" or standard rod?

 

If you don't have the tools to measure yourself. Find a reputable machinist & have them measure the crank & bore before ordering parts. The manual will give you the specs that you need to fall in to.

[ri702bill 8,968]

If you opt to go to the larger K181 bore, you most likely can go with the STD size. That still leaves meat to bore .010 over later.....

Either way - the Machine Shops NEEDS the piston and rod you intend to use before they attempt to finish size it. A GOOD shop adjusts the actual size of the bore to give optimum piston skirt to wall clearance on the low side of the tolerance to allow for wear without piston slap.... Same goes for the fit of the rod on the journal... A sub-par shop just gets a fit within the specified range and calls it good enough.

Edited June 24, 2023 by ri702bill

[kpinnc 13,728]

23 minutes ago, ri702bill said:

A GOOD shop adjusts the actual size of the bore to give optimum piston skirt to wall clearance on the low side of the tolerance to allow for wear without piston slap.... Same goes for the fit of the rod on the journal...

 

So true! Even more so when aftermarket parts are in common use. Back when you could buy OEM, it wasn't as bad because the parts were made in spec by the same manufacturer. 

[WHX?? 50,716]

11 hours ago, Sailman said:

 

What would be the purpose of an ACR cam from a K 181? Would the cam that's in the current motor work if its not damaged?

It lets the motor turn over easier making for easier starts. 

You can use use the stock non ACR cam no problem but stay with the double belts on a 701. 

Both my 1045 & 1055 have non ACR cams but do labor to start. Good compression on rebuilt motors. 

[Jon Paulsen 291]

11 hours ago, Achto said:

 

If you don't have the tools to measure yourself. Find a reputable machinist & have them measure the crank & bore before ordering parts. The manual will give you the specs that you need to fall in to.

I would just add cheap measuring tools get very expensive if they result in short engine life. To measure the crank journal, you'll want it out on the bench and very clean. 

[ri702bill 8,968]

There are procedures to throughly check the bore for actual size, top, midway, and the bottom of the piston travel to determine actual size AND taper. Taper is inherent from the power stroke down when combustion occurs. Some engines use an offset wrist pin to give more torque (the 4 cylinder GM Iron Duke was one) - with the downside of increased sideload and taper....

The crank journal needs to be checked at at least 80 degree intervals - center, left and right. Forget using a dial caliper for this - you NEED to use a CALIBRATED micrometer for this. And a consistant pressure on the anvil when measuring. Remember - the rod clearance is .0015 to .0020 inches. No room for measuring error.

I am a believer in using Plastigage to verify the final rod clearance at assembly. It tells you both the actual gap and if it even across the journal.... The last step prior to assembly.

Piston rings usually require hand filing to get the endgap "correct" - that spec is rather wide. Too much gap increases blowby, insufficient gap the ends can butt, that breaks the ring...

All this is covered in detail in the Kohler Engine Manual. As Jon said - clean is absolutely required.

Bill

[Jon Paulsen 291]

I wholeheartedly 2nd the plastigage. It's cheap, easy to use, accurate and about any parts shop stocks it. And it never lies. 

[ri702bill 8,968]

47 minutes ago, Jon Paulsen said:

I wholeheartedly 2nd the plastigage. It's cheap, easy to use, accurate and about any parts shop stocks it. And it never lies. 

And - it confirms that all the effort and money spent will be worth it - unless you assemble the connecting rod with the oil hole facing that WRONG way... that gets expensive quick.... all TOO easy to do that!

Edited June 24, 2023 by ri702bill

[Wheel-N-It 2,971]

Just my 2cents, but  I would reach out to Paul @oldredrider, and see what he recommends.

Again, this is just my 2cents. I'm certainly not trying to minimize what anyone else here has recommended. Its getting late (my eyes are getting tired) and I have been standing in the rain at the big show this week lol

[Wheel-N-It 2,971]

@Sailman , so what have you come up with for the 701 ?

[Sailman 1,299]

I am still sorting out what to do. I appreciate all the input and guidance from the folks on this forum concerning the rebuild. I unfortunately don't have the space or the skill set to do the rebuild and probably pretty costly to have a shop do the work. Debating on putting a predator motor in to get it running or just offer it for sale to one of the guys here that would be able to restore it correctly. Its pretty complete and being a 701 its a unique one.