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Spark Plug

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Hi Folk, 

Me again, what number spark plug do you use on your K181 engine. I have searched the service manual and can only find the Kohler part number!

 

I am still having problems with it, a bit of smoke I may have to have a rebore.

 

Anyone going to Wiston next weekend, perhaps I could have a chat with? 

 

Thanks

Terry

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Manual reccommends Champion RCJ8 0.025" gap (unless running on propane etc). Not sure if modern ones are as good as the old ones, so here is a cross reference for loads of alternatives 

grabbed from the net-

RCJ8.JPG.ff31401a527ba4c398d286e25ac8c557.JPG

 

 

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In most of my gas engine I use Autolite plugs, but in the chainsaw NGK or Bosch seem to work better. Champion plugs don't seem to be the same quality as they were years ago

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  As to the bit of smoke. Does it use much oil? After a couple of hours running, My C-125 needed an oil top up. A deglaze and new rings and now it uses none.

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Stormin

Thanks for your reply I didnt get back sooner been away at a steam rally only just got home.

I did used a new set of ring from Cox & Turner with the scraper ring being a one piece as apposed to the three split type I thought they were gapped correctly but I am now thinking that is where my problem is.

This weekend I had to top up the oil by 300 ml didnt smoke much only on start up,  comlete strip down now, and start again.

Thanks Terry

 

 

 

 

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 Just make sure, if you don't know, to stagger the ring gaps. When I removed the piston from my C-125, I found the gaps were in line.

It may not have needed new rings. :rolleyes:

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21 hours ago, Stormin said:

 Just make sure, if you don't know, to stagger the ring gaps. When I removed the piston from my C-125, I found the gaps were in line.

It may not have needed new rings. :rolleyes:

It’s certainly good practice to stagger ring gaps when assembling an engine; wherever possible I try to avoid having a gap on the thrust side of the piston. It’s generally accepted that rings rotate during use, known I believe as cyclic rotation, so all the gaps ending up in line is strange indeed. 

 

 

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Curiosity got the better of me I couldn’t wait until the winter, now stripped the engine down and could find only one possible problem causing excessive oil consumption, it used 300ml in 2/3 hours use, and the oil ring gap was only about 20 degree away from the middle ring gap and should have been 120 degree a third apart, do you thing the close proximity could be the problem?

 

The manual quotes a maximum of .027 ring gap I have less than .015 on all the new rings.

 

All other measurements are within manual specifications.

Terry

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With the older Cat diesel engines, sometimes to help "break 'em in" a small teaspoon of Bon Ami cleaner was slowly fed into the air intake. In a Honda portable generator that was burning oil after an overhaul I used the Bon Ami treatment, but less than half a teaspoon very slowly fed in after I'd taken the air filter off. That seemed to cure the problem.

 

Just an idea

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8 hours ago, 857 said:

Curiosity got the better of me I couldn’t wait until the winter, now stripped the engine down and could find only one possible problem causing excessive oil consumption, it used 300ml in 2/3 hours use, and the oil ring gap was only about 20 degree away from the middle ring gap and should have been 120 degree a third apart, do you thing the close proximity could be the problem?

 

The manual quotes a maximum of .027 ring gap I have less than .015 on all the new rings.

 

All other measurements are within manual specifications.

Terry

As far as I can see, you dont mention glaze busting / honing the bore before fitting the new rings. If that has not been done it is almost certainly the cause of the higher than expected oil consumption.  

Also, did you check that the cylinder dimensions were within spec for re-ringing - both diameter and out of round ?  It would be normal practice to check those measurments at three positions covered by the piston  movement in the bore - top middle and bottom.  They would be the deciding factor when considering whether the engine is suitable for re-ringing or is in need of a rebore..

Finally, I know that for some engines Kohler do a "service ring set" specifically to take up wear within the prescribed limitations.  Also, the Cords piston ring company can supply special ring sets for worn engines and I see that they list sets for Kohlers.. 

 

image.png.9ae6fd7af8cc5fe5a1134b932e3b0d6b.png

 

 

 

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Yes I did hone the bore but maybe not enough.

 

I decided to phone a rebore company of 35 years experience in high performance  motor bike engines and I can see them tomorrow, they are prepared to check the engine over including  measurements  while I wait, I may have something to report back tomorrow.

Thanks for all your comments.

Terry 

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There are several possible reasons for excessive oil consumption in these older 'K' engines, so I'm not sure if you have covered all of them off yet?.

Use of correct Oil. It is often experienced that use of modern synthetic blends etc in these engines can cause high consumption. They were designed for Mineral based Oils.

A good 30 wt oil of spec as specified in the manual for air cooled, splash lubrication will always serve well.

It is also possible that fitting new rings to a worn/used bore will not improve it's current condition very much. It may be worn 'out of round' , of which there is a limit quoted.

As mentioned, deglazing a cylinder can work wonders for a tired engine, but it needs to be done correctly to resemble the finish of a newly honed engine.

Kohler recommend the honing marks should intersect at approx 30degrees, and if these marks are either too steep or shallow, the oil consumption/friction can increase.

Here is an example of the correct honing finish (after a rebore)-

DSC00628.JPG.ce86cf664ecaebc007b3fbd264f5ba64.JPG

 

There is another area to check, if not already done so.

The valve guides are a possible cause and can have the same affect as worn rings on Oil use and by causing the crankcase to be pressurised, instead of running

with a partial vacuum.

These are good engines and are readily able to be rebuilt, so I for one am pleased with your clear determination to get this one back up to spec.

I hope your potential engine rebore service is local to you.

It's a few years since I had a K301 fully worked by Sutton Rebore Services and I was so impressed by their standards and prices.

The sound of an almost 'back to new' engine running as it should is payment enough. 

Regards        

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Quote. "The valve guides are a possible cause and can have the same affect as worn rings on Oil use and by causing the crankcase to be pressurised, instead of running

with a partial vacuum."

 

Also, it's as well to check the operation of the crankcase breather valve which is incorporated into the valve chest cover. Its  correct operation is essential for maintaining negative pressure in the crankcase to assist in keeping it oil tight.

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