K181 Build

[RED-Z06 2,144]

1 hour ago, WHX?? said:

 

I'll let @Achto elaborate but it comes from building Harley motors in that if the piston leaves the jug it gets new rings.  Something about they won't reseat I think... worn to the shape of the bore? 

I don't subscribe to the theory that rings  spin on the piston.  If they do why bother  to stagger end gaps? 

Piston rings on 4 strokes must spin to keep the grooves free of carbon, staggering ring gaps is good practice but the gaps will overlap from time to time.  Rotation cam vary by engine speed, and load, the rings can rotate slowly, quickly, or even in opposite directions.  A study was done and a report published on the phenomenon.

 

https://digital.library.unt.edu/ark:/67531/metadc60141/

[RED-Z06 2,144]

51 minutes ago, WHX?? said:

I guess I have seen that on chain saws. 

2 stroke rings are pinned because the rings move past the ports, ring gaps will typically be pinned to straddle either side of the intake port.  You'll also see on some 2 strokes, a protrusion down the center of the port called a tonsil, it provides support to the ring, if a ring catches on a port its game over.

[wallfish 15,972]

5 hours ago, RED-Z06 said:

2 stroke rings are pinned because the rings move past the ports, ring gaps will typically be pinned to straddle either side of the intake port.  You'll also see on some 2 strokes, a protrusion down the center of the port called a tonsil, it provides support to the ring, if a ring catches on a port its game over.

Interesting! That makes perfect sense too

I haven't seen that on the Homelite XL-12 chainsaw motors or the little O&R engines. Just rebuilt 7 little O&Rs since Jan 1 and did 3 or 4 Homelites over the past few years. Just normal rings

[WHX?? 46,961]

Speaking of things rotating in a motor. 

This little doodad was the keeper on this 181. Guessing it's a valve rotator? Asked @Achto if he had it on his 8 he went thru... no. 

On the exhaust valve. 

Did not see it in the parts manuals I have. 

All the engines i have been in never saw it before. 

Edited February 22 by WHX??

[RED-Z06 2,144]

34 minutes ago, WHX?? said:

Speaking of things rotating in a motor. 

This little doodad was the keeper on this 181. Guessing it's a valve rotator? Asked @Achto if he had it on his 8 he went thru... no. 

On the exhaust valve. 

Did not see it in the parts manuals I have. 

All the engines i have been in never saw it before. 

Part number 52 413 01-S.  Ive seen some without them, mine had it, a troy bilt tiller i tore down didnt.  Theory is that the exhaust valve rotating prevents hot spots and carbon buildup, which reduces the likelihood of valve/seat burning.

[squonk 39,046]

Yup 1 K181 I had 2 years ago had one and the other one didn't.

[WHX?? 46,961]

This was a service motor. Maybe they were trying to cover all the spec bases for replacements. 

[Sailman 1,134]

Looking in the Kohler service manual it shows that as the valve rotator on the exhaust valve. Also stated there may be one on the intake valve as well.

[Sailman 1,134]

I have an update on my 704 work. Checked the bore and it appears to be a k-141 with all measurements at 2.875 inches. Taper varied only .0004 and Out of Round .0007 so I think I am good to go there.

Pulled the valves and here are pictures of them after good cleaning on the wire wheel and some 1000 polishing on the exhaust valve. Do you think they are good to go? The exhaust valve has an indented part (see pics). Is that normal? They both fit quite snug in the valve guides so hope I can use them as they are.

Also I have hardly any valve lash at the tappets. Is that OK on the K-141? Kohler manual doesn't give any data on the K-141 or is same as 161 except for bore size? Thoughts all you re builders???

Having some fun now!!

[squonk 39,046]

If that valve stem is worn that much the guide isn't too far behind. 

[RED-Z06 2,144]

3 hours ago, Sailman said:

I have an update on my 704 work. Checked the bore and it appears to be a k-141 with all measurements at 2.875 inches. Taper varied only .0004 and Out of Round .0007 so I think I am good to go there.

Pulled the valves and here are pictures of them after good cleaning on the wire wheel and some 1000 polishing on the exhaust valve. Do you think they are good to go? The exhaust valve has an indented part (see pics). Is that normal? They both fit quite snug in the valve guides so hope I can use them as they are.

Also I have hardly any valve lash at the tappets. Is that OK on the K-141? Kohler manual doesn't give any data on the K-141 or is same as 161 except for bore size? Thoughts all you re builders???

Having some fun now!!

Looks like factory undercut on the valve 

[WHX?? 46,961]

I'll second that Red. Don't listen to Sqounky those are normal. Both of mine have it. 

Intake valve looks good both seats look good. Exhaust valve looks like it could use a little shining up by way of some lapping. I would give both a quick lapping. 

2 hours ago, RED-Z06 said:

 Kohler manual doesn't give any data on the K-141 or is same as 161 except for bore size? 

All small blocks are the same. We'll maybe not the 91.  Exhaust is larger due to hotter valve. 

Mine were just a silky one larger than spec but I'll live with it. Some guys like to go-to the tighter side on the adjustable ones less valve tick they claim. 

 

Otherwise looking good Saildude. 

Edited February 22 by WHX??

[WHX?? 46,961]

Mine is starting to look like a motor. Head tin  stays off until bench running and torque check. 

[squonk 39,046]

Haven't seen that on any Kohler valve I've run across. Wonder what the purpose of it was.

[squonk 39,046]

2 minutes ago, WHX?? said:

Mine is starting to look like a motor. Head tin  stays off until bench running and torque check. 

Are those sheet metal screws in that carb?

[WHX?? 46,961]

I never saw it till this 8 Squonky Certainly not on any big blocks. 

Some kind of anti stick Red? Help oiling to the guide?  

Edited February 23 by WHX??

[WHX?? 46,961]

4 minutes ago, squonk said:

Are those sheet metal screws in that carb?

What the ones for the air filter? 

[squonk 39,046]

Yes . The ones that would hold the filter base.

[Sailman 1,134]

59 minutes ago, WHX?? said:

Exhaust valve looks like it could use a little shining up by way of some lapping. I would give both a quick lapping. 

 I did lap both valves already. Think the exhaust needs some more? Don't think the exhaust valve is too burned?

Also, not clear on the valve lash. Lash measure on mine is almost non existent. Is that ok or do I need to take some off the valve stem?

Manual calls for tappet clearance intake .006 / .008. Exhaust .017 / .019

Min lift zero lash intake .2718. Exhaust .2482

Just not sure what all that means? Does it even need any valve lash? The valves lapped with good contact. Advice please from you guru's.

Edited February 23 by Sailman

[RED-Z06 2,144]

12 minutes ago, Sailman said:

 I did lap both valves already. Think the exhaust needs some more? Don't think the exhaust valve is too burned?

Also, not clear on the valve lash. Lash measure on mine is almost non existent. Is that ok or do I need to take some off the valve stem?

Manual calls for tappet clearance intake .006 / .008. Exhaust .017 / .019

Min lift zero lash intake .2718. Exhaust .2482

Just not sure what all that means? Does it even need any valve lash? The valves lapped with good contact. Advice please from you guru's.

In: 0.006-0.008 in.

Ex: 0.017-0.019 in.

 

This is the lash specs 

 

The min lift you are seeing is them measuring the lobe lift, you would use feeler gauges to fill the lash gap then a dial indicator to measure total valve lift.

[Sailman 1,134]

1 minute ago, RED-Z06 said:

In: 0.006-0.008 in.

Ex: 0.017-0.019 in.

 

This is the lash specs 

 

The min lift you are seeing is them measuring the lobe lift, you would use feeler gauges to fill the lash gap then a dial indicator to measure total valve lift.

 

If I understand correctly, just get the lash within specs (with valves closed) and don't worry about the "min lift"? I haven't opened up the bottom end and don't plan to. Thanks.

[WHX?? 46,961]

13 minutes ago, squonk said:

Yes . The ones that would hold the filter base.

No but I think they are metric... forgive me @ebinmaine for  I have sinned again. In my self defense It was on the shelf and it's giterdone.   The old carb is in the box but tagged as f$%&ed. 

 

As far as the exhaust valve I like to see that nice shine around the valve but not a deal breaker if it doesn't.  Make sure the cam lobes are not

trying to lift the valve. 

10 minutes ago, Sailman said:

 

If I understand correctly, just get the lash within specs (with valves closed) and don't worry about the "min lift"? I haven't opened up the bottom end and don't plan to. Thanks.

Correct. 

[oliver2-44 8,898]

6 hours ago, RED-Z06 said:

Looks like factory undercut on the valve 

Yep, the Service engine on my C81 has that undercut. On the exhaust. I itiallyI thought it was worn and bought a new one that was undercut the same. 

[RED-Z06 2,144]

Backcut/undercut valves are supposed to be for added performance, im not sure what the net gains is on a 6.25hp flathead...but its a good thing

[ebinmaine 63,362]

8 hours ago, WHX?? said:

forgive me @ebinmaine for  I have sinned again. In my self defense It was on the shelf and it's giterdone.   The old carb is in the box but tagged as f$%&ed. 

 

You need an intervention???