Bobcat M731 Kohler 14hp engine issues

[chesterspal]

Bought this Bobcar M731 a few weeks ago. It has a Kohler K321 14hp engine,

Fellow said he messed with the (aftermarket) carb because it was running rich. Then, he never got it to run again, so he sold it.

The carb was rusted shut, so I replaced with another aftermarket from Amazon. I also found it running rich from the get-go.

So far I have also replaced the fuel, oil and air filter, the plug (H10C), points and condensor and added a see-through fuel filter as there was none..

There is plenty of compression. It is a bear to move the pullys on by hand and the OEM starter is having a hard time turning it over. I have a new one coming tomorrow.

I have the manual for it and I have checked the two lifter gaps (they were fine), the spack plug gap (set to .025), the new points set to .020.

To get it to even start, I set the choke to full on and the throttle fully out. Turn the key and push in the throttle and adjust the choke to about half way after it kicks over.

Adjusting the idle screw seems to do little but stop the engine at some point. I get no real speed increase to back off from. I own a half dozen bikes so I know what to listen for and I do not get that with this engine.

I have cleaned the (new) carb twice so far but it is clean every time I open it.

No matter what I have tried after three days I get a fully blackened plug avery time. I cannot seem to get this engine to run leaner no matter what I try. It chokes and stumbles when I even try to give it more fuel.

It has the OEM fuel pump on the engine. The metal version with the primer lever underneath. I have tested it and it's fine. Although a lack of gas does not seem to be my issue, here.

Suggestions?

Thanks for any help you can provide.

 

[foton]

I would guess that your float height is wrong and overfueling the engine , or the needle and seat are not shutting off the fuel like it is designed to do. k321 engines are long lasting all iron engines will take alot of use. A new carb might be the answer if you can not correct the problem. Check your oil and make sure that you have not gassed up the engine oil.

 

[chesterspal]

Hey thanks.

The more I ponder this problem, the more I now think it has to do with the ignition verses the fuel.

Tested the resistance of the 16" ignition wire that leads from the coil to the plug. Came back around 10,000 ohms. That just seems way too high to produce a decent spark and may be the reason I'm getting carboned up plugs after just a few minutes of running and then engine failure.

They make ignition wire with a solid copper core that has 0 ohms resistance. I ordered a short piece off Ebay and will give that a try.

I now think this may be the issue. Will report back in a few.

 

[foton]

I agree solid copper wire for those, not carbon resistor wire.

 

[foton]

and really a non resistor spark plug too.

 

[chesterspal]

The plug I'm using is the recommended Champion H10C, which has no resistor. I will also try the Autolite 216 version that some feel is a better made plug.

Interestly, I also purchased a new ignition coil ($15.00 on Amazon) that arrived yesterday evening, and clearly stamped on the casing is "Requires No External Resistor".

 

[foton]

I believe that reference to a resistor on the coil is refering to a resistor placed on the 12 volts feeding the coil, it was supposed to make the points last longer. so that coil has a internal resistor placed in the winding as most are these days. I remember chrysler had a external resistor and they would get hot and would crack and breakdown and go open ,as a temp fix you could put the two wires together and go down the road.

 

[chesterspal]

I see. Thanks.

 

[Chris 8603]

The plug I'm using is the recommended Champion H10C, which has no resistor. I will also try the Autolite 216 version that some feel is a better made plug.

Interestly, I also purchased a new ignition coil ($15.00 on Amazon) that arrived yesterday evening, and clearly stamped on the casing is "Requires No External Resistor".

That just means the coil doesn't need the step down power resistor. Solid core wire will put more power to the plugs

 

[Firefighter]

You say you have plenty of compression would be curious to know how much it actually has

 

[chesterspal]

You say you have plenty of compression would be curious to know how much it actually has

What should it be?

Does this Kholer K321 have compression release?

Usually, if you are not seeing smoke, the rings should be fine.

 

[oiu789]

Make sure the after market carb is jetted correctly for your engine.

 

[Firefighter]

compression should be from 110 to 120 psi with throttle at full travel, much less than 100 will cause problems
i dont believe they have a compression release, but i may be wrong

 

[chesterspal]

I think I have it, now.

Until I was able, through trial and error, get the correct gaps for the points and plug I could not get this engine to run worth a damn.

Shooting soot out the muffler as it sputtered and popped then died

Plugs were blackened from too rich a mixture and nothing I tried messing with the carb would correct for that.

I finally hit on what got me a decent running engine with no soot and no pops.

For this engine…

Points: .022 (book said .020)

Plug: .023 (book said .025)

Got me running strong. Fine tune as needed as I run this in the yard for a bit.

Then, I'll install a virgin Autolite 216 plug.

 

[oiu789]

Check float level and that the needle and seat are not leaking by.

 

[oiu789]

The 731 has a deutz f2L511 32 hp diesel engine. I think you must have a 371.

 

[chesterspal]

m371, correct. My bad.

Carb is fine. Issue was ignition timing.

I'm all set, thanks