The K-301 build

[Gregor 4,846]

I have read about cylinder leak down tests, but have never seen it done. I watched a video, and that confused me more than it taught me. I got a tester, read the instructions word for word, and went to it. I found my TDC, and turned on the air. I could hear a LOT of air coming out of the muffler. I must be doing something wrong.   I took the valve cover off, which is more work than you might think on a 321. I checked for clearance from the exhaust valve to tappet, ~ .015. Clearance on the intake valve, ~ .005. I don't know what spec is, but irregardless there is clearance. Hooked my tester up again. Still a LOT of air coming from the muffler. The dial on the left shows how much air I am putting into the cylinder. The dial on the right shows how much air is staying in the cylinder. That's not good. At least a valve job is in order. Tomorrow I will get my bore gauges out and check the cylinder.

 

Sorry.. It's a K301.  12 HP

Edited May 5, 2021 by Gregor

[pfrederi 17,741]

Exhaust valve is burned and leaks...ACR has failed and is keeping it open???

[Achto 27,604]

At low RPMs or not running the ACR should keep the exhaust valve palatially open at TDC. This is why a compression test is inconclusive on a Kohler K model. A leak down test can be preformed but the piston can not be at TDC.

[Gregor 4,846]

25 minutes ago, pfrederi said:

ACR has failed and is keeping it open???

I mentioned I had .015 clearance on my tappet. exhaust valve had to be closed. But, curiosity got the better of me. I had to pull the exhaust valve. I expected to see it badly burnt, or even a chunk missiing, but there wasn't. At first glance, it didn't look that bad. Then I looked closer. The valve is warped. I know you can't tell it in the pic, but there is a .010 feeler gauge under one side, and a .009 feeler gauge on the other side. The middle is firmly touch the paper on this marble tile. It's very obvious when you look at it close.A while back there was a discussion about what harm can be done, by running a motor with no muffler. Someone mentioned a warped valve as a possible result. I questioned that at the time. I may have to re-think that theory.

[Gregor 4,846]

I think you can actually see it in this pic.

[Gregor 4,846]

5 hours ago, Achto said:

but the piston can not be at TDC.

Where should the piston be?

[ebinmaine 67,612]

7 hours ago, Gregor said:

see it in this pic

WOW

[Achto 27,604]

2 hours ago, Gregor said:

Where should the piston be?

 

The exhaust valve should close again a few degrees past TDC. 

[Gregor 4,846]

I was going to do a valve job on this motor, and let it go at that. Then I checked the cylinder bore. Max is 3.378. Mine is 3.381. Of course as always, these are not Starett gauges. I decided to do a complete rebuild, and remove the balance gears. I've never done a big block. This will probably have to be done on the floor, as there is no way I can get it on my work bench.

 

P.S.  If someone could change the title of this thread to "The K-301 build" I would appreciate it.

[ebinmaine 67,612]

6 minutes ago, Gregor said:

change the title

You can change it yourself if you go back and edit the first post. Just scroll up and fix the title.

 

 

[ebinmaine 67,612]

11 minutes ago, Gregor said:

This will probably have to be done on the floor, as there is no way I can get it on my work bench

Do you have a place to consider adding a small light-duty chain falls or similar setup using rope?

[Gregor 4,846]

24 minutes ago, ebinmaine said:

You can change it yourself if you go back and edit the first post. Just scroll up and fix the title.

 

 

Learn something new every day.

Edited May 5, 2021 by Gregor

[Gregor 4,846]

20 minutes ago, ebinmaine said:

Do you have a place to consider adding a small light-duty chain falls or similar setup using rope?

Not really I have an electric hoist in the middle of the garage, but that doesn't do much good.

[953 nut 55,317]

35 minutes ago, Gregor said:

This will probably have to be done on the floor, as there is no way I can get it on my work bench

You may want to buy a lift table, it is a real back saver and can double as a work area.  https://www.harborfreight.com/500-lbs-capacity-hydraulic-table-cart-61405.html

[ebinmaine 67,612]

1 minute ago, Gregor said:

Not really I have an electric hoist in the middle of the garage, but that doesn't do much good.

Maybe a small roll around table that's the same height as your workbench?

 

Lift engine to table. Roll table to workbench. Slide engine to workbench.

 

Tell the commandant it's for arts and crafts usage of the household but always conveniently have something on top of it so it can't be incongruously commandeered. 

[squonk 41,155]

I have a 1/2 ton Harbor Fright chain hoist to lift Kohlers off of tractors on to my Harbor Fright lift table. The table can lift 2 thumpers at once. I have also modified a Harbor Fright engine stand to hold 1. 

 

 

[ebinmaine 67,612]

10 minutes ago, squonk said:

modified a Harbor Fright engine stand

That's the one piece of the puzzle I don't have here and I wouldn't mind having an engine OFF of the rolling table.

 

What did you have to do to the engine stand specifically?

 

 

[squonk 41,155]

21 minutes ago, ebinmaine said:

That's the one piece of the puzzle I don't have here and I wouldn't mind having an engine OFF of the rolling table.

 

What did you have to do to the engine stand specifically?

 

 

Had to drill a couple of 7/16" holes in the plate and get some 7/16" x 6 1/2 bolts with some pipe nipples. I have another thumper to tear into so I can take a pic. a lot of guys use just the 2 starter holes but I like the extra security of 4 bolts.

[Gregor 4,846]

16 minutes ago, squonk said:

 but I like the extra security of 4 bolts.

So would I !

[pfrederi 17,741]

11 hours ago, Achto said:

At low RPMs or not running the ACR should keep the exhaust valve palatially open at TDC. This is why a compression test is inconclusive on a Kohler K model. A leak down test can be preformed but the piston can not be at TDC.

At low RPM the acr will open the exhaust valve just a bit for a brief time as the piston comes up.  By the time it is at TDC the valve is completely closed.  It is closed a bit before other wise you would have a problem as the plug fires just before TDC

[Gregor 4,846]

The motor is all disassembled. The cylinder and piston look excellent. The rod journal measures 1.4985. The max wear limit is 1.499. I am guessing the shop will tell me, 10 over on the piston, and 10 on the crank. We shall see..

[Gregor 4,846]

8 minutes ago, pfrederi said:

At low RPM the acr will open the exhaust valve just a bit for a brief time as the piston comes up.

I wonder if you could get an accurate compression test, if you could some how spin the motor at 800 RPM.

[pfrederi 17,741]

4 minutes ago, Gregor said:

I wonder if you could get an accurate compression test, if you could some how spin the motor at 800 RPM.

I would think so.  Maybe yuo could hook up an electric motor to the PTO pulley and spin it fast enough. Some say you can get an accurate test if you can crank the engine over backwards. To me not worth the effort.  A leakdown test is better as it gives you a clues as to the cause of the lack of compression.. 

[MikMacMike 479]

2 hours ago, squonk said:

I have a 1/2 ton Harbor Fright chain hoist to lift Kohlers off of tractors on to my Harbor Fright lift table. The table can lift 2 thumpers at once. I have also modified a Harbor Fright engine stand to hold 1. 

 

 

Ahhhhhhhhh Ive got 2 engine stands that Ive used for all the car engines, and after all these years Squonk I never thought of doing what you did there, You smarty pants hahahaha. rest assured my next K plant will be married to my stand next time. Wicked.

[ebinmaine 67,612]

Anyone have any info about these?

 

From Kirk...

 

Have you removed balance gears from your K-series engine and discovered that it now vibrates with newfound gusto? Or have you thought about buying a newer, twin-cylinder tractor just to get rid of the single-cylinder shakes? This modification will greatly reduce transmitted vibration, making your K-series engine run noticeably smoother, restoring both your faith in Kohler and the feeling in your hands and feet.

A 50% RBF (Reciprocating Balance Factor) is a good compromise in reducing transmitted vibrations from a single-cylinder engine. For reasons unknown, Kohler engineers under-balanced these engines (only 29% RBF on the K301) such that they transmit unnecessarily high unresolved reciprocating forces about the vertical axis. Installing the Crankshaft Balance Plate Kit restores a 50% RBF to the engine, making for a much reduced vibration signature. The improvement in crankshaft balance yields lower main bearing loads contributing to longer engine life, reduced transmitted vibrations, and greater operator comfort.

This inexpensive kit requires simple and straight-forward machining of your crankshaft which can be done at a local machine shop in usually less than one hour. Or, if your personal shop is equipped with a mill and drill press, you can easily do it yourself. No further balancing of the crankshaft assembly is required if installed per the instructions. The kit consists of a precision formed, high-quality steel Balance Plate, two grade 8 mounting screws, and detailed instructions. This modification is for Kohler K301, K321, and K341 single-cylinder engines only.