Piston

[Howie 899]

Saw something today I had heard about but never seen before. Fellow brought me a K241 this week

to grind the valves on and possibly put in a new set of rings. Cleaned top of piston off and it is marked

.003. Will see where this goes. 

[ebinmaine 72,739]

I don't have enough knowledge of the Small Engine World to say that I've seen one of those...

In big engines however, quite a few times. It was an old trick we used to use many moons ago when we did not want to spend the money or take the time to have an engine bored out.

 

[WHX?? 51,784]

Very common Howie to have factory pistons marked that . Was some kinda factory thing been told.  

Measure things as should and bounce your findings off the specs to see if you can squeak by with a just a re-ring or gotta go 10/20/30  over. Check existing ring end gaps and piston to bore measures. 

Most importantly is the condition of the bore, out of roundness, taper and all that lovely stuff. Also the condition of the piston is of prime considerat ion 

[Howie 899]

I have never seen them listed in the parts manuals, think the factory did this to use a block 

bored a little large. At least that is what I have read before.

[Achto 29,405]

2 minutes ago, Howie said:

I have never seen them listed in the parts manuals, think the factory did this to use a block 

bored a little large. At least that is what I have read before.

 

This is exactly the info that my research has came up with also.

[ebinmaine 72,739]

5 minutes ago, Howie said:

I have never seen them listed in the parts manuals, think the factory did this to use a block 

bored a little large. At least that is what I have read before.

In the v8 car engines if they were worn fairly evenly 6 or 8 thousandths over they would use two or three thousand oversize Pistons, or maybe knurl the skirts.

 

First I've seen of a small engine doing this but it definitely makes sense.

[WHX?? 51,784]

In a nutshell Howie if you see one with a 003 marking consider it factory and measure accordingly.. There is no substitute for accurate measuring.

Edited April 4, 2019 by WHX22

[Howie 899]

I have rebuilt quite a few of these engines but the first one I have ever run

into like this. Had heard of it just never saw one. I have bore gave and all 

I need to check the block. Cylinder looks good will have to see what the piston

looks like. 

 

[WHX?? 51,784]

Same here Howie ... I'm sure other guys will be along to chime in about the 003 business. That's why I am just suggesting measure, those figures tell the truth. 

[Achto 29,405]

Kohler rings from OPE engines.

 

https://www.kohler-engine-parts.opeengines.com/index.php?main_page=product_info&products_id=6108

[953 nut 60,086]

Long and short of it is that in the manufacturing process not all blocks came down the line with a perfect cylinder. Some were re cut at .003 over to save the block, some even left the factory at .010 over. 

[Pullstart 66,843]

1 hour ago, 953 nut said:

Long and short of it is that in the manufacturing process not all blocks came down the line with a perfect cylinder. Some were re cut at .003 over to save the block, some even left the factory at .010 over. 

 

There’s no replacement for displacement!  

[WHX?? 51,784]

11 hours ago, Achto said:

Kohler rings from OPE engines.

 

They ain't exactly given them rings away tho are they? I suppose OEM Kohler!

Wonder if the rings for a std bore were commonly used with the 003 piston?

Keep us informed with what shakes Howie, the number of 241's I have to eventually go through I am more than likely going to run into this.

Next question was a 003 used on the other K series or M blocks? looking at Dan's link to those rings it says they are for a 341 so I'm thinkin so?

 

From the link

Piston Rings Standard & .003 Bore, Fits new style Mahle piston design used in K341 & M16 engines. 45 108 10-S

Edited April 4, 2019 by WHX22

[Achto 29,405]

29 minutes ago, WHX22 said:

Wonder if the rings for a std bore were commonly used with the 003 piston?

 

Dealing with only .003 I would think it would have been common. .003 would be past the wear limits of the piston but still within reach for the rings

[oldredrider 2,553]

It is recommended by Kohler to use standard rings on a .003 over piston.

It's not really uncommon to run across the .003 blocks...but then, I've done "quite a few" Kohlers.

[953 nut 60,086]

8 hours ago, WHX22 said:

They ain't exactly given them rings away tho are they? I suppose OEM Kohler!

Best place is on .  I have sold a lot of NOS Kohler ring sets for $ 25.00 with free shipping. I don't have any K-241/M-10 rings or I would have PMed by now.

Edited April 4, 2019 by 953 nut
fat finger

[WHX?? 51,784]

Agreed Richard, I see them resonable ther in old tattered nos boxes but then I see them for $$$$. Of all the aftermarket stuff to keep these motors running I personally would like to use Kohler rings. Unfortunately this being a hobby and I'm not looking for pulling champion prize money or flying at 33k ft my wallet tells me to settle for Chinese.

[Spareparts 85]

How much are you paying for 341 K-series rings,  ordered Kohler rings and just about died $181.00

 did I get taken????

[Achto 29,405]

8 hours ago, Spareparts said:

did I get taken????

 

Hate to say, but I fear you may have.

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

[953 nut 60,086]

                      Lots of genuine New Old Stock rings on  for $ 35 to $ 40.                 

[Spareparts 85]

I thought so, but the bad part is they are sitting on my bench and I don't think I will build that engine now.