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C-125 Won't Fire

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Wheel horse c-125 with kohler 301 engine wont fire but turns over. I have made sure there is fuel getting to the engine and there is a strong enough spark to start it. Also we have good enough compression.

So what is the problem?

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Have another spark plug you can try? They will fire out of the engine but can fail when placed under compression.

 

Garry

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We just renewed the spark plug, brand new but didn't help.

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Is the plug wet with gas after cranking?? if you are sure you have spark and the plug is wet and you have compression then we have to look at timing.  You need Fuel, compression and spark (at the right  time) to have an engine work.  Sounds like you have all three but the spark is coming at the wrong time.Do you have access to a timing light, or a multimeter?

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Yes I do have access to a multimeter, what do I need to do?

 

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Remove spark plug.  Can you find a small metal plug on the blower shroud. Probably on the front maybe below the coil. Pry it off then slowly turn the engine over there will be two marks punched on the edge of the flywheel.  One will have a T the other an S.  If you have some paint you may wish to highlight them they can be hard to see.  Disconnect the wire from the coil that goes to the points.Then put red probe form your multi meter on that then connect the black one to a know good ground.  set multimeter to measure ohms lowest setting is good.

 

  The meter will read 1 (open) or show a very low resistance. Then slowly turn the engine over. Hold your finger over the plug hole when you feel compression starting to build your meter should show a very low resistance.  Continue turning very slowly until the meter will suddenly show 1 (open).that is the points opening and when they would fire the plug. Now look in the hole ans see if you can see the S mark.  If you can then you are timed correctly.  However if you can't see it slowly move the engine forward or back a bit until you should only have to move it a fraction of a turn to reveal the mark.  If you have to go forward Clockwise on the flywheel end then your timing is way to advanced if you have to turn it anti-clockwise then you are too retarded. 

 

To adjust points open the cover   A setting of .020 should get it running and have the S in the center of the hole if not readjust points and remember opening points advances the spark closing them a bit retards it.

Edited by pfrederi
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I looked through the hole at the fly wheel but the edge of it was too rusty to find any marks whilst I turned it slowly.

Screenshot_20170625-182632.png

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First check the point gap with feeler gauge.  Turn motor till points are open and not moving. Check gap should be about .020 (which normally will let them start and run...just maybe not so well).  Did this motor ever work for you?? 

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Alright will have to borrow a feeler gauge, yes this motor worked very well for me for around a year until it suddenly after a month didn't start

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Hopefully setting the points to .020 will get her running.  However to get her runnng her best you will have to get the timing so she fires when the S is in the window.  May have to pull the air shroud and clean up the edge of the fly wheel.  I think Kohler had a 98 pound weakling stamping the flywheels...some are pretty faint.  Whilst you are out borrowing try to borrow a timing light.

Edited by pfrederi
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I just measured the point gap and it was around .015, would this make much of a difference though? Should I change it to .02.

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Never mind I just changed it to match .02 and it still didn't fire. Later I'll try and clean up the fly wheel.

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Curious how are you testing the spark.  from what I have read if you pull the spark plug wire and hold it 1/8"  from the plug (still in the head) it should jump the gap while cranking (obviously insulate your self from the wire for this test.

 

If your coil is weak you may have a spark with the plug laying on the head but not when it is under compression

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Yes we have tested the spark plug in various ways, one of the ways you listed we tried as well 'pull the spark plug wire and hold it 1/8"  from the plug (still in the head) it should jump the gap while cranking'.

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Had the exact same problem.  Found that I wired the condenser to the wrong side of the coil.  everything I read said that it should not make a difference-short term ...but it did.  Put it on the correct side and it fired right up.  Learn something new every day

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IF you have a compression checker or gauge you can also use it to find TDC (top dead center). You can get a little tissue paper also and not plug the spark hole tight . but lightly tight an under compression the tissue paper should pop out this showing your on compression stroke and getting close to TDC to find your fly wheel mark

 

Edited by Tim.0

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13 hours ago, Fin_ said:

I looked through the hole at the fly wheel but the edge of it was too rusty to find any marks whilst I turned it slowly.

Screenshot_20170625-182632.png

Have used a piece of wood dowel to ride on the flat side of the flywheel. Easier done if it will run but have done it with the spark plug removed and cranking the starter. The dowel will polish the rust where it contacts the flywheel and leave the timing mark untouched so it is visible.

 

Garry

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Does removing the spark plug allow one to insert a dowel rod into the cylinder and touch the piston top? If so simply insert a dowel rod and rotate the flywheel until the piston comes to TDC and then take a paint marker to mark where the missing mark is.

Edited by 6bg6ga

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Engine won't fire. Check to see if there is voltage to the ignition coil when in start and in run with your meter. If no voltage make up a jumper wire to go from battery to the coil + and with the plug back in try to start it. If it still will not run swap out the coil and try it again.

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On 6/26/2017 at 2:08 AM, gwest_ca said:

Have used a piece of wood dowel to ride on the flat side of the flywheel. Easier done if it will run but have done it with the spark plug removed and cranking the starter. The dowel will polish the rust where it contacts the flywheel and leave the timing mark untouched so it is visible.

 

Garry

:text-yeahthat:

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Alright will try all of these and get back to you this weekend, thank you for your help.

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On 6/27/2017 at 6:20 AM, 6bg6ga said:

Does removing the spark plug allow one to insert a dowel rod into the cylinder and touch the piston top? If so simply insert a dowel rod and rotate the flywheel until the piston comes to TDC and then take a paint marker to mark where the missing mark is.

That doesn't work on K series Kohlers Plug is not over the piston

 

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12 hours ago, pfrederi said:

That doesn't work on K series Kohlers Plug is not over the piston

 

 

I guess that would be obvious to anyone removing the spark plug. No real need to find TDC anyway. At .015-.020 its going to be close enough for the engine to start anyway. Visual observation of the points alone would supply enough information.

Edited by 6bg6ga

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I just tried getting rid of the rust on the flywheel so I could see the marks on it but couldn't find anything, is this good enough to be able to see the marks?

IMG_20170702_183159444.jpg

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use a bright flashlight and go slow I would think you would be able to see it. Unless it was stamped that bad. I found mine and it had more rust on it than that, then maybe it was just stamped better. use your hand so you know your on the compression stroke and it might help narrow it down some.

The rust may be in the stamp yet you might find the stamp by the outline.

It gets frustrating I have been down this road before just take your time.

 

Also when the points close make sure you have continuity you can use your multi meter for that. Sometimes the points need to be cleaned up some. Had this  happen this spring when I try to start a ford tractor that had sat over a year. I tracked the problem to the points not making contact, but they were closing and gap was correct. I clean to points with  emery cloth. Then rechecked gap,I rechecked with my meter and had continuity when closed, I didn't have continuity before. Put the distributor back together and tractor started right up.

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