K241 initial measurements for rebuild/fix

[rsshallop]

Hello, My progress on rebuilding the K241 for my cub 108 is coming along at full turtle speed. Well, At least there is some progress. And, this is one of the first posts I have made since joining this website that isn't a shout out for help. So, I feel good about that. After cleaning the valve guide on the exhaust side both guides appear to be withing usable specs (measured with a mic).

Exhaust guide: mid-point between .312 and .313
Intake guide: mid-point between .312 and .313

(ol'George, you were right. The reamer did clean up a considerable amount of carbon. I'm sorry I didn't that a picture of the carbon on the end of the reamer to document)

Next is the cylinder bore (taken several times with my mic and telescoping gauge)

A axis top center and bottom: 3.252, 3.251, 3.251
B axis top center and bottom: 3.253, 3.252, 3.252

(I'm pretty sure that these measurements fall will within the max wear limit 3.2545, max out of round .005 and max allowable taper .0015)

Next, the crankpin. These measurements were very difficult to take

A axis left middle and right: mid-point between 1.50 and 1.499
B axis left middle and right: mid-point between 1.50 and 1.499

( I think I will be OK here too with a max out of round of .0005 and a max taper of .001)

Next, camshaft end play: .013 (taken with a feeler gauge)

******************

Using these measurements I plan to take the block to someone in town that I met who does small engine repairs. He has some hand tools to hone the cylinder wall with a new cross hatch and cut the valve seat to 45 degree angle. Then, I will re-measure the cylinder bore to see if it is still within specs. If all is good, I will the order new parts to put it back together.

- new exhaust and intake valves
- new STD piston, rings and connecting rod.
- shim kit for camshaft end play
- new governor gear

Also, the pully/PTO end of the crankshaft needs a new key path cut into it. I will have to have that done at a machine shop.

Hope this posting finds everyone well,

Ross

[ol'George]

Originally Posted by rsshallop

Hello, My progress on rebuilding the K241 for my cub 108 is coming along at full turtle speed. Well, At least there is some progress. And, this is one of the first posts I have made since joining this website that isn't a shout out for help. So, I feel good about that. After cleaning the valve guide on the exhaust side both guides appear to be withing usable specs (measured with a mic).

Exhaust guide: mid-point between .312 and .313
Intake guide: mid-point between .312 and .313

(ol'George, you were right. The reamer did clean up a considerable amount of carbon. I'm sorry I didn't that a picture of the carbon on the end of the reamer to document)

Next is the cylinder bore (taken several times with my mic and telescoping gauge)

A axis top center and bottom: 3.252, 3.251, 3.251
B axis top center and bottom: 3.253, 3.252, 3.252

(I'm pretty sure that these measurements fall will within the max wear limit 3.2545, max out of round .005 and max allowable taper .0015)

Next, the crankpin. These measurements were very difficult to take

A axis left middle and right: mid-point between 1.50 and 1.499
B axis left middle and right: mid-point between 1.50 and 1.499

( I think I will be OK here too with a max out of round of .0005 and a max taper of .001)

Next, camshaft end play: .013 (taken with a feeler gauge)

******************

Using these measurements I plan to take the block to someone in town that I met who does small engine repairs. He has some hand tools to hone the cylinder wall with a new cross hatch and cut the valve seat to 45 degree angle. Then, I will re-measure the cylinder bore to see if it is still within specs. If all is good, I will the order new parts to put it back together.

- new exhaust and intake valves
- new STD piston, rings and connecting rod.
- shim kit for camshaft end play
- new governor gear

Also, the pully/PTO end of the crankshaft needs a new key path cut into it. I will have to have that done at a machine shop.

Hope this posting finds everyone well,

Ross

Check that the crankshaft, where the keyway is wallowed out, that it is not worn undersize,
if not, then put the new keyway *90 to the old one.

Just use a dingle-berry/ ball hone to de-glaze the bore for new rings.
You don't want to remove any material, making an already worn bore larger.

When measuring the crank, the most worn part is where the piston is at the top of the stroke, and the least, 1/2 way down, (*90) that is your comparison to be read.
Also check in the same position to see if the crank pin is tapered about it's length, in-other-words on the surface that would see if the rod was rocking side to side, causing a taper on the crankpin.
In an ideal situation, the crankpin would show no wear or taper.
An out of round crankpin will knock during usage as will a worn pin.

Your combined cyl taper is .002 top to bottom max.
It will work, but it will use just a tad of oil as the piston rings will be expanding/contracting as they go up/down and you have an out of round condition where the wall contact will be lost.
---- But oil usage will use less than it does now.
The right way would be to bore/hone to first oversize, but an economical fix is re ring as you plan.
Don't know how long you plan on keeping it or how many hours you are going to use it.

[rsshallop]

Yes, ol'George, I do have a lot to consider before I proceed any further. The tractor doesn't even have a PTO or mowing deck, and it needs a lot more than just engine work to get up to a good standard. If I proceed as I have planned, then I have put a lot of new parts into a engine rebuild, that as you have pointed out, may not run as well for as long as I would like. Furthermore, what am I going to do with this tractor when I am finished the project? I want to work it for sure and that will require attachments. The only benefit I have derived from buying this tractor so far is the pleasure of working on it and learning a little bit about the history of the IH company (which is all pretty cool in itself). Maybe all I end up with this summer is a rebuilt engine that I can deploy at some future point? Yes, lots for me to think about. Thanks for your feedback.

[rsshallop]

In the meantime, I will recheck the crankshaft as you have indicated.

[dodge trucker]

Kohler makes (well, made) an 0.003" over (yes 0.003" besides an 0.030") piston for those engines, the K301 before the last one that I did, I used one. I lucked out and found one cheap on Ebay. the machinist said it would be fine as it came out at between 0.025 to 0.003 over standard when honed, max is 0.0035". It would be bored "next time". I had gotten a Ebay kit, which I still have most of here…. as yet unused. I miked the kit piston and the NOS 0.003 piston and the 0.003 piston was actually 0.005 bigger than the kit piston.
The kit piston was at the low end of piston diameter tolerance, cyl was at the high end of max diameter allowed before overbore.
so with the 0.003 OS piston in a bore that came out straight and true at 0.0025" over standard, I would up with an engine that had perfect bore to pist0n clearance.
This piston used STD rings and end gap was in the middle of spec range.


Scout around Ebay, don't buy the 1st one you see, anything I buy there I find the same part with a W-I-D-E range of prices. The piston I got for that 301 came with rings (some don't) and the wrist pin (again some don't) was OEM Kohler, still had 1/2" layer of dust on the box even after shipping/ handling, and cost me $40 shipped. while others wanted $200 for the same exact piston and rings.
I try to use OEM parts for internal engine stuff as much as possible.
I just put together a K321 for another machine, and with this engine is the very 1st time for me using a "kit" piston rings and rod. I'm very leery of that 1st startup as a result/
not a fan of parts from "across the pond" and never have been

[REO Clinton]

Mahle is located where?

[rsshallop]

Thanks Dodge Trucker. I'm probably going to bore it out .010 over as ol'George recommended. What he said about the rings losing contact from the cylinder wall because of the taper pretty much made up my mind for the better. I've been down to Lindsey last week and the auto supply shop there offers machine shop services at what I am guessing would be a reasonable rate (probably around $80.00 for the bore out and to cut the valve seats). I've also ordered a new governor gear kit off ebay and am looking around for a new piston, wrist pin, clips, rings, connecting rod and valves. I'm trying to determine that middle ground between good quality and reasonable pricing (with good quality having the upper hand). At any rate, I need the piston before I take the block to the machinist as that is what he recommended. I'll let you know how it is coming along once I get all the parts assembled.

[ol'George]

Check out 'bat4kids" on ebay.
He sells a lot of rebuild kits reasonable.
Personally I haven't used them, but others have, and have good things to say about the stuff he sells.
Ask us if you have questions.