Kubota 125s begins to lose power after warm up.

[doc craker]

ok. fairly certain I have located the proper tool.
on the way. Be here tommorrow.

thanks

 

[Auto Doc's]

ok auto doc's.

all I have is the bulb type. You attach it to the plug and then the plug wire. Not reliable?
OK . I will order the other one. Do happen to have a link or good description of the tester?

Oregon Small Engine Spark Tester for Briggs 19051 19368 Kohler Honda Tecumseh | eBay

Works with Briggs and Stratton, Kohler, Honda, and Tecumseh 2 and 4 cycle engines. Includes 1 in line spark tester as picturedItem Specifications Test while engine is running or cranking.

www.ebay.com

 

[Auto Doc's]

Just to explain the bulb type: It does not have an open air gap to stress the coil to "jump" a spark. The bulb design is a fluorescent light basically and does not create the need stress to test the coil properly.

When you test, look for consistent spark. The engine will at least run on one cylinder, so check both by placing the tester inline between the plug and the wire. Be careful not to get shocked.

This may be a situation where a plug or coil as simply quit working when hot, so make sure to test both when cold and hot.

Also be sure to check at both idle and at high RPM.

 

[slomo]

One of the cylinders is not firing. Hard to believe that a 2 cylinder engine would still run smooth after dropping a cylinder.

One of those FLIR infra red cameras was exactly what you needed to SHOW you which one was or was not firing. Perfect tool for the job.

ok auto doc's.

all I have is the bulb type. You attach it to the plug and then the plug wire. Not reliable?
OK .

No not accurate is a better word. An open gap style, one can make the gap larger or smaller to stress out the coil. Also testing while running, you will see low revs might be ok. Then possibly fail at mid and high revs, coil giving up the beans.

Throw the Christmas bulb type tester in the trash. Doesn't take hardly any spark energy to light off one of those bulbs. It doesn't stress out the coil confirming strong spark.

This is what you need. I just picked up another one off fleabay for like 2 bucks shipped. The best one is a PET-4000. Cadillac top of the line testing tool.

Quick & Simple Way to Check for Ignition Spark Using An Adjustable Spa

The ignition spark tester provides an easy way to eliminate the ignition coil as a cause of problems when you're having a no-start with no fire situation. You can download a PDF manual for repeatedly check.

www.hipastore.com

In Line Spark Plug Tester High Energy Ignition Coil Engine Auto Diagnostic Tool | eBay

Advantage of ignition spark tester： Determine the quality of the coil based on the color of the sparks and the flashes in the distance Intuitive and easy to understand the operation of the ignition coil Alligator clip securely fixed to the ground Screw assembly allows quick and easy adjustment...

www.ebay.com

 

[Tiger Small Engine]

One of those FLIR infra red cameras was exactly what you needed to SHOW you which one was or was not firing. Perfect tool for the job.

No not accurate is a better word. An open gap style, one can make the gap larger or smaller to stress out the coil. Also testing while running, you will see low revs might be ok. Then possibly fail at mid and high revs, coil giving up the beans.

Throw the Christmas bulb type tester in the trash. Doesn't take hardly any spark energy to light off one of those bulbs. It doesn't stress out the coil confirming strong spark.

This is what you need. I just picked up another one off fleabay for like 2 bucks shipped. The best one is a PET-4000. Cadillac top of the line testing tool.

Quick & Simple Way to Check for Ignition Spark Using An Adjustable Spa

The ignition spark tester provides an easy way to eliminate the ignition coil as a cause of problems when you're having a no-start with no fire situation. You can download a PDF manual for repeatedly check.

www.hipastore.com

In Line Spark Plug Tester High Energy Ignition Coil Engine Auto Diagnostic Tool | eBay

Advantage of ignition spark tester： Determine the quality of the coil based on the color of the sparks and the flashes in the distance Intuitive and easy to understand the operation of the ignition coil Alligator clip securely fixed to the ground Screw assembly allows quick and easy adjustment...

www.ebay.com

View attachment 73036

I use the spark tester that lights up with orange light all the time. I also have the other type that jumps the gap.

A less technical, yet very effective way to test that both cylinders are firing on twin cylinder engine:
Use a spray bottle with water to spray the exhaust pipe and watch how quickly it disappears. The other way is to simply put your hand on the valve cover and check for heat.

 

[doc craker]

@ Tiger Small Engine, your idea worked perfect. It was how I determined the cylinder that was not working.

 

[doc craker]

This is what I discovered today. The tester came in the mail a day late.

The right side cylinder is the one that is not firing. I placed the tester on the wire as instructed and there was no spark at all.
To double check my ground, I checked the other cylinder. There was good spark on that one.
I noticed the ignition module on the right side, the not firing one, was very close to the flywheel contact point compared to the other side.

I measured the distance on both for comparison. the right side was at .004 and the left side is .008.
I was wondering what the proper space is?
Should I adjust the right side? Should I just replace it?
I have a little time this afternoon to mess with it.

Thanks

Doc

 

[slomo]

Most are 0.008" but check YOUR engine manual for proper specs.

 

[doc craker]

Most are 0.008" but check YOUR engine manual for proper specs.

Thanks slomo. If the one side is too close will it prevent it from producing spark?

 

[slomo]

Thanks slomo. If the one side is too close will it prevent it from producing spark?

No.

When things warm up they tend to expand. Being that close of 0.004", might scrape the flywheel. Keep both sides at 0.008".