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Here a spark plug, there a sparkplug...

#1

grumpygrizzly

grumpygrizzly

OK, I've picked quite a few weed ceaters, chainsaws, leaf blowers etc from yard sales over the years and I've been trying to get them up and running. First thing is to dump the gas, then check the sparkplug to see if theres any spark left in it..

Here lies my delima: Where ccan I find a good cross reference for what plugs will work for these things.. I've got a bunch of various new sparkplugs I've pickled up through my years of yardsales and I'm hoping some will work in these old motors. Chanpions, NGK, and a few more I don't remember the letters on.

A computer program would be MOST awesome or even an app I could put on my cell phone. Any help would be greatly appreciated. I have a piece of paper around here that mentioned Jacks Small Engine and theres Chicanic but, I don't know if she has anything on her website.

I'm not in this as a business, I just have a HUGE shop in y backyard (14'x60' that's LOADED with tools and I've always liked working on small engines.. Got 3 or 4 books on repairing them but, lookin at the publishing date, they were written before computers came along.. Some of the basics are still applicable but, lets face it, they're almost better off going into my firep[ace in my shop to give me a little heat new and then.

OK, I'll shut up now.. Hope to hear some ideas soon.


#2

Tiger Small Engine

Tiger Small Engine

grumpygrizzly said:
OK, I've picked quite a few weed ceaters, chainsaws, leaf blowers etc from yard sales over the years and I've been trying to get them up and running. First thing is to dump the gas, then check the sparkplug to see if theres any spark left in it..

Here lies my delima: Where ccan I find a good cross reference for what plugs will work for these things.. I've got a bunch of various new sparkplugs I've pickled up through my years of yardsales and I'm hoping some will work in these old motors. Chanpions, NGK, and a few more I don't remember the letters on.

A computer program would be MOST awesome or even an app I could put on my cell phone. Any help would be greatly appreciated. I have a piece of paper around here that mentioned Jacks Small Engine and theres Chicanic but, I don't know if she has anything on her website.

I'm not in this as a business, I just have a HUGE shop in y backyard (14'x60' that's LOADED with tools and I've always liked working on small engines.. Got 3 or 4 books on repairing them but, lookin at the publishing date, they were written before computers came along.. Some of the basics are still applicable but, lets face it, they're almost better off going into my firep[ace in my shop to give me a little heat new and then.

OK, I'll shut up now.. Hope to hear some ideas soon.
Click to expand...
Google “spark plug cross reference”, that’s how I do it. Sites will have the information.


#3

StarTech

StarTech

First you look-up the IPLs to see what the OEM used before attempting to cross reference plugs. But one plug that seems to be a problem is the NGK-CRM6 and 7 plugs which I replace with the Bosch equal. Otherwise nearly everything gets crossed to NGK. Just cuts down the number of different in stock.


#4

Tool_Maker_Tim

Tool_Maker_Tim

grumpygrizzly said:
OK, I've picked quite a few weed ceaters, chainsaws, leaf blowers etc from yard sales over the years and I've been trying to get them up and running. First thing is to dump the gas, then check the sparkplug to see if theres any spark left in it..

Here lies my delima: Where ccan I find a good cross reference for what plugs will work for these things.. I've got a bunch of various new sparkplugs I've pickled up through my years of yardsales and I'm hoping some will work in these old motors. Chanpions, NGK, and a few more I don't remember the letters on.

A computer program would be MOST awesome or even an app I could put on my cell phone. Any help would be greatly appreciated. I have a piece of paper around here that mentioned Jacks Small Engine and theres Chicanic but, I don't know if she has anything on her website.

I'm not in this as a business, I just have a HUGE shop in y backyard (14'x60' that's LOADED with tools and I've always liked working on small engines.. Got 3 or 4 books on repairing them but, lookin at the publishing date, they were written before computers came along.. Some of the basics are still applicable but, lets face it, they're almost better off going into my firep[ace in my shop to give me a little heat new and then.

OK, I'll shut up now.. Hope to hear some ideas soon.
Click to expand...
I also have a yard full of string trimmers that I am repairing to sell. I too dump the old fuel, replace the spark plug, air and fuel filters, and (before I remove and clean the carb) I try and see if they will turn over (hope springs eternal) The main function of a department store string trimmer is to get the user to become winded, frustrated, and dedicated to finding a retailer who deals in reputable equipment and ultimately purchasing one of the products they represent (Stihl, Echo, Shindaiwa, Redmax,etc.) If I can be of any assistance, please contact me via the site's email. As for your Alternate Spark plug crossover info, start with the User Manual for the trimmer. These can be downloaded as .pdfs for free on most manufacturers websites. After determining the manufacturers recommended spark plug from the manual, my goto publication is SPARKPLUG CROSSREFERENCE https://www.sparkplug-crossreference.com. I just googled "an alternative for a NGK BPMR7A spark plug" https://www.sparkplug-crossreference.com/convert/NGK_PN/BPMR7A. Click on the link, and check out the information that this site provides! Not only some alternative plugs but also Specs for your plug such as the hex size.
Good luck, and don't hesitate to reach out to me. My other than keyboard commando name, is Tim.


#5

B

bentrim

After getting the starter cord ripped out of my hand by equipment with NGK plugs, I have decided NGK stands for No Good Kind.
By the way replaced the NGK with any other plug and unit ran perfectly.


#6

R

RevB

NGK is not the cause of "ripping the cord out of your hand" .

As regards plug choice you are looking to be in the same heat range as the OEM plug as well as the obvious physical characteristics. No more, no less. If a two stroke is fouling plugs it's gas/oil ratio, type of oil, plug heat range, lower than normal compression.


#7

B

bentrim

RevB said:
NGK is not the cause of "ripping the cord out of your hand" .

As regards plug choice you are looking to be in the same heat range as the OEM plug as well as the obvious physical characteristics. No more, no less. If a two stroke is fouling plugs it's gas/oil ratio, type of oil, plug heat range, lower than normal compression.
Click to expand...
This was especially Honda push mowers Yes more than one, would be hard to start, pop back thru the carburetor, pop out the muffler, plus pull the cord back. Changed the plug mower would start easily and run good.


#8

R

RevB

NGK is not the cause of "ripping the cord out of your hand" .

As regards plug choice you are looking to be in the same heat range as the OEM plug as well as the obvious physical characteristics. No more, no less. If a two stroke is fouling plugs it's gas/oil ratio, type of oil,
bentrim said:
This was especially Honda push mowers Yes more than one, would be hard to start, pop back thru the carburetor, pop out the muffler, plus pull the cord back. Changed the plug mower would start easily and run good.
Click to expand...
Explain the mechanism that caused this. Spark plugs are extremely dumb. They spark when the points or electronics tell it to, at the advance or retard the points or electronics tell it to. They don't add add or detract power tho the manufacturers try to convince buyers otherwise. The voltage they spark at is determined by the coil or electronics. About the only reason would be the plug was not the same physical spec as the OEM recommended. Electrode gap, porcelain volume, porcelain and center electrode protrusion, plug threaded length, resistor. None of these would advance timing, only retard it very slightly.


#9

B

bentrim

RevB said:
NGK is not the cause of "ripping the cord out of your hand" .

As regards plug choice you are looking to be in the same heat range as the OEM plug as well as the obvious physical characteristics. No more, no less. If a two stroke is fouling plugs it's gas/oil ratio, type of oil,

Explain the mechanism that caused this. Spark plugs are extremely dumb. They spark when the points or electronics tell it to, at the advance or retard the points or electronics tell it to. They don't add add or detract power tho the manufacturers try to convince buyers otherwise. The voltage they spark at is determined by the coil or electronics. About the only reason would be the plug was not the same physical spec as the OEM recommended. Electrode gap, porcelain volume, porcelain and center electrode protrusion, plug threaded length, resistor. Nome of these would advance timing, only retard it very slightly.
Click to expand...
I cannot explain the why. I can only say what was done and how it was fixed. The only explaination I can think of was the plug was partially fouled. Yes I don't understand why the timing was changed, only that it was. And that by changing the plug the issue was corrected. I replaced the plug with a Champion of the correct heat range, the same heat range as the NGK and what was recommended by Honda. Nothing was changed except the spark plug, same fuel, same ignition unit, same carburetor and air filter, even checked the flywheel key, was not sheared even slightly. It was more than one mower that did this and it was different owners. The first one to do this took quite a while to figure out as I blamed it on every thing except the spark plug.


#10

R

RevB

bentrim said:
I cannot explain the why. I can only say what was done and how it was fixed. The only explaination I can think of was the plug was partially fouled. Yes I don't understand why the timing was changed, only that it was. And that by changing the plug the issue was corrected. I replaced the plug with a Champion of the correct heat range, the same heat range as the NGK and what was recommended by Honda. Nothing was changed except the spark plug, same fuel, same ignition unit, same carburetor and air filter, even checked the flywheel key, was not sheared even slightly. It was more than one mower that did this and it was different owners. The first one to do this took quite a while to figure out as I blamed it on every thing except the spark plug.
Click to expand...

"Latest Spark Plug Brand Rankings

According to the latest global automotive spark plug rankings, NGK spark plugs are still firmly at the top of the list, and their excellent ignition performance and excellent durability have been unanimously praised by car owners. Followed closely by Champion Spark Plug and Bosch Spark Plug. These two brands also have a long history and profound technical accumulation in the field of spark plugs. In addition, brands such as Denso Spark Plug, Torch Spark Plug, Deco Spark Plug, Starlight Spark Plug, New Star Spark Plug, and Autolite Spark Plug are also at the forefront by their respective advantages."

NGK owns 58% of all OEM specified sales. 🤫


#11

A

Auto Doc's

bentrim said:
I cannot explain the why. I can only say what was done and how it was fixed. The only explaination I can think of was the plug was partially fouled. Yes I don't understand why the timing was changed, only that it was. And that by changing the plug the issue was corrected. I replaced the plug with a Champion of the correct heat range, the same heat range as the NGK and what was recommended by Honda. Nothing was changed except the spark plug, same fuel, same ignition unit, same carburetor and air filter, even checked the flywheel key, was not sheared even slightly. It was more than one mower that did this and it was different owners. The first one to do this took quite a while to figure out as I blamed it on every thing except the spark plug.
Click to expand...

bentrim said:
I suggest you may have had a bad experience with counterfeit NGK plugs. They are "grey market" imported Amazon garbage mostly, but they find their way to small parts stores struggling to stay in business.
Click to expand...

I have dealt with this in both small engine and automotive applications.

Most modern spark plugs are made with a resistor pellet inside the porcelain segment. The resistor has to be correct for the spark plug to work correctly.

One solution is to make sure you have genuine plugs or use non-resistor designs.


#12

B

bentrim

These were usually OEM Honda installed plugs. As I said I could not explain the why, I can only say what happened and after replaceing the plugs with Champion had no more problems. They only reason I can put on the problem was there was a problem with the resistor in the plugs. By the way the Champions were a resistor plug.

If you haven't seen it here is some interesting information on Champion and AC plugs.

www.hagerty.com

How Albert Champion(ed) Two Major Spark Plug Brands - Hagerty Media

Albert Champion was responsible for two spark plugs companies: Champion, of course, and AC. His story is a remarkable one.
www.hagerty.com www.hagerty.com


#13

A

Auto Doc's

bentrim said:
These were usually OEM Honda installed plugs. As I said I could not explain the why, I can only say what happened and after replaceing the plugs with Champion had no more problems. They only reason I can put on the problem was there was a problem with the resistor in the plugs. By the way the Champions were a resistor plug.

If you haven't seen it here is some interesting information on Champion and AC plugs.

www.hagerty.com

How Albert Champion(ed) Two Major Spark Plug Brands - Hagerty Media

Albert Champion was responsible for two spark plugs companies: Champion, of course, and AC. His story is a remarkable one.
www.hagerty.com www.hagerty.com
Click to expand...
Another issue to consider when buying used plugs (resistor type), even slightly used is risky due to an unknown history or any rough handling. Plugs are rather tough, but if they are dropped on a concrete floor hard or multiple times, there is a high risk that the resistor pellet has been fractured, and they would fail quickly.

Another factor that people often overlook is the "heat range". There are plug manufacturer charts that explain this pretty well.

I have run into incorrect heat range issues a few times over the years. That is usually identified by an engine that misfires and shuts down when hot. Once it cools it restarts until it gets hot again. It is easy to condemn a coil for this problem, so swapping the plug is usually the quickest solution to confirm the problem area.


#14

B

bentrim

Auto Doc's said:
Another issue to consider when buying used plugs (resistor type), even slightly used is risky due to an unknown history or any rough handling. Plugs are rather tough, but if they are dropped on a concrete floor hard or multiple times, there is a high risk that the resistor pellet has been fractured, and they would fail quickly.

Another factor that people often overlook is the "heat range". There are plug manufacturer charts that explain this pretty well.

I have run into incorrect heat range issues a few times over the years. That is usually identified by an engine that misfires and shuts down when hot. Once it cools it restarts until it gets hot again. It is easy to condemn a coil for this problem, so swapping the plug is usually the quickest solution to confirm the problem area.
Click to expand...
As cheap as spark plugs are I never use used sparkplugs unless it is a known good for testing only to be replaced by a new plug.
Yes I agree sometimes people don't respect the spark plug and careless handling especially when dropped on the floor result a damaged plug. I have seen insulators broken and the ground electrode damaged or closed by careless peole.
Also had a NEW plug without a ground electrode installed.

As to heat range Yes it can causes issues including as you explained or even engine damage from the wrong heat range. Usualy too cold fouls plugs and too hot may cause detonation and engine damage.

As for customers doing their own work I have had seen flat head engine that require a RJ19LM come in with a Rc12YC installed and vice versa.


#15

sgkent

sgkent

The timing and the spark voltage are affected by the plug gap, not how beefy the coil is. The electrons do not care what conductor is carrying them, other than some plugs and wires, rotors etc., that have resistors built into them to limit ignition current. The timing change by changing the gap is infinitesimal, but it is there. If the gap is too small, the firing voltage will be too low. If it is too wide, it may exceed the coil's output, or the di-electric inside the coil, wires etc.. If a starter rope pulls backwards, that is not the plug. In fact, if it snapped back, the flywheel / magneto could have been out of time, and the change moved the flywheel back to the correct spot, in which case it will be back. I have only seen one set of bad NGK plugs and that was in my Opel GT over some 50 years ago. I use NGK, Champion, and Denso. All are good brands in my humble opinion. In fact, I often just glass bead the old plug to clean it up, re-gap it, and reuse it the next time I need one. Almost everything I own that runs on gasoline starts on the first or second pull.


#16

B

bentrim

sgkent said:
The timing and the spark voltage are affected by the plug gap, not how beefy the coil is. The electrons do not care what conductor is carrying them, other than some plugs and wires, rotors etc., that have resistors built into them to limit ignition current. The timing change by changing the gap is infinitesimal, but it is there. If the gap is too small, the firing voltage will be too low. If it is too wide, it may exceed the coil's output, or the di-electric inside the coil, wires etc.. If a starter rope pulls backwards, that is not the plug. In fact, if it snapped back, the flywheel / magneto could have been out of time, and the change moved the flywheel back to the correct spot, in which case it will be back. I have only seen one set of bad NGK plugs and that was in my Opel GT over some 50 years ago. I use NGK, Champion, and Denso. All are good brands in my humble opinion. In fact, I often just glass bead the old plug to clean it up, re-gap it, and reuse it the next time I need one. Almost everything I own that runs on gasoline starts on the first or second pull.
Click to expand...
I have no doubt that major spark plug manufacturers are making good products whether it is NGK, Champion, AC, Bosh, Denso or others. I know what happened and had a sore hand for a week. Also as stated before the first one was totally checked out, carb, coil, flywheel key, valve settings, fuel, etc. The only thing that fixed it was replacing the spark plug. The other techs in the shop did not believe me either --- until it happened to them. I wish I had saved some of those plugs so I could prove I wasn't daydreaming. My personal choice is Champion but I have seen them fail too, but not that way.


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