Does the wrong spark plug hurt your saw?

[7oaks]

Every one of the used saws I've purchased recently has had the wrong spark plug (according to the ipl, manual and acres site). I've cross referenced them and some aren't even close and some not even listed!

Has this hurt these saws?

I've searched and found the following thread which answers some questions but it isn't stated if there is damage to a saw if used with the incorrect plug.

http://www.arboristsite.com/showthread.php?t=59867&highlight=wrong+spark+plug

Here is some of the knowledge gleaned from this thread:

"I know guys have used all kinds of other plugs with success as have I, but for the average guy this is the plug (one recommended by shop or sales person checking cross reference). The reason is The "6" in the Bosch number represents the heat range of the plug. And regardless of what "Billie-Bob" at the local parts store tells you, 6 in Bosch is different than a 6 in Champion, or ngk, or Denso, etc. Most foreign plugs the lower the number the hotter the plug. Domestic brands are the opposite.

So I ended up two heat ranges too cold........I wonder why I kept fowling plugs????????? I think this is an easy thing to over-look because spark plugs seem so simple. They can cause a lot of problems." spencer13ca

"In addition to the heat range and physical size, the non-screw top is specified (and needed)." Lakeside53


"I always try and run the same plug that came from the factory, my Polaris snowmobile came new with champion plugs, if I run ngk I will have fouling trouble, even though the cross reference chart says its the correct plug.

I'm thinking sometimes when you cross reference to a different brand, the heat range may not be exactly the same. I don't know how else to explain why else this would happen (assuming the catalog is correct)" yodayoda

I have had problems finding the Bosch plugs so have purchased a couple of the Autolite cross referenced ones to try (I didn't realize until today how many have the incorrect plugs and want to search out and purchase the correct ones from now on).

But back to my original question...Have these saws been damaged by using the wrong plugs and if so what kind of damage (a couple were way off in heat range!

Maybe the answer to this question will help some other members.

 

[MrGiggles]

Too hot of a heat range could make the engine and plug run hot and possibly melt a hole in the piston, and if it's too big (like an OHV plug) the piston could hit it. I don't think there are any major side-affects of running a colder plug other than less performance and it fouling up.

 

[MrGiggles]

Lots of good info in this vid.

http://www.youtube.com/watch?v=jdGdMmmD2YU

 

[djmercer1]

i never had the need to with a chain saw, but with my old yamaha enticer i would change the plug fro 5-6-7 based on the time of the year and what type of work i was doing with her.... if she didnt like to run right, change the plug heat range and voila purring like a kitten...

 

[7oaks]

Lots of good info in this vid.

http://www.youtube.com/watch?v=jdGdMmmD2YU

Thanks for the link. I learned quite a bit from it.

i never had the need to with a chain saw, but with my old yamaha enticer i would change the plug fro 5-6-7 based on the time of the year and what type of work i was doing with her.... if she didnt like to run right, change the plug heat range and voila purring like a kitten...

Interesting concept thanks for sharing.

 

[J.W Younger]

3 most important things-1 clearance, no exposed treads to fill with carbon or contact with piston 2-ability to disapate just enough heat and run hot enuff to keep deposits off 3- resistance, carbon piles and other resistance puts more strain on the coil and reduce spark energy at low speeds. Champion cj7y covers most saws, I,m sure someone will disagree.

 

[buzz sawyer]

Make sure the seat is correct - gasket or tapered. I don't know if any saws require a tapered seat, but the Husky 268 I aquired had one - incorrectly. I'm thinking this caused the lean mixture that scored the piston.

 

[Edge & Engine]

Dolmar did a test with different types of non-approved spark plugs and their effect on coils. According to Dolmar, in the worst case the coil failed within minutes. It's very important to use a resistor plug if that is what the MFG recommends.

 

[CGC4200]

improper spark plugs

Last spring, I was trying to get a small chain saw to run to slice up
all of the ice storms limbs in my yard.
I tried the old Poulan S25 Deluxe and even after I replaced the
rotten fuel lines, it would not turn over real good.
I had installed a lawnmower plug in sometime in the past,
slightly longer threads and it must have been hitting the carbon
buildup on top of piston.

 

[J.W Younger]

Dolmar did a test with different types of non-approved spark plugs and their effect on coils. According to Dolmar, in the worst case the coil failed within minutes. It's very important to use a resistor plug if that is what the MFG recommends.

this is good advice as you don't know what electronics are in place and ther design, rev limiters etc.

 

[7oaks]

Make sure the seat is correct - gasket or tapered. I don't know if any saws require a tapered seat, but the Husky 268 I aquired had one - incorrectly. I'm thinking this caused the lean mixture that scored the piston.

Dolmar did a test with different types of non-approved spark plugs and their effect on coils. According to Dolmar, in the worst case the coil failed within minutes. It's very important to use a resistor plug if that is what the MFG recommends.

Thanks guys...More info I didn't know about. I'm learning more about spark plugs than I thought there was to learn.

 

[Erick]

Dolmar did a test with different types of non-approved spark plugs and their effect on coils. According to Dolmar, in the worst case the coil failed within minutes. It's very important to use a resistor plug if that is what the MFG recommends.

YEP!! it's that way with husky now too. The ole bosch standby of "Number 7's" (WS7F) for the Huskys and "Number 6's" (WSR6F) for Stihls is a thing of the past. More and more of the newer saws are requiring a resister plug now. Best to check the specs, I’d hate to fry a $100.00 module over a $2.00 sparkplug.

 

[buzz sawyer]

YEP!! it's that way with husky now too. The ole bosch standby of "Number 7's" (WS7F) for the Huskys and "Number 6's" (WSR6F) for Stihls is a thing of the past. More and more of the newer saws are requiring a resister plug now. Best to check the specs, I’d hate to fry a $100.00 module over a $2.00 sparkplug.

When resistor plugs first came out in autos, the purpose was to prevent radio static. Had nothing to do with the rest of the ignition system - according to Champion reps. Resistor wires came out at the same time.

Are you saying the resistor is required on these saws to control current flow during coil secondary discharge or to protect against damage from electromagnetic induction? Are you sure it's not just to prevent noise in any radios nearby - i.e. in homeowners saws?

 

[belgian]

Are you sure it's not just to prevent noise in any radios nearby - i.e. in homeowners saws?

I was convinced that's the only thing to it. No influence on the plug itself, so I read somewhere.

 

[motobike]

Spark Plug 101

Let me add my 2 cents; based on 2-stroke motorcycles:
Spark plug reach, seat type, resistor, have already been discussed so let me say many 2-stroke motorcycle pistons have been ruined by incorrect spark plugs. mainly wrong heat range.
The term heat range, refers to the rate at which the spark plugs can transfer or dissapate the heat generated during combustion from the firing end of it's insulator through the cylinder head and cooling system.

There is more to this than I can put in one paragraph; but caution must be used not to get too far out of the engine's intended heat range of plug. GOOGLE spark plug basics or something and study up on this. We are in an era of changing fuels also, EPA regulated, which can affect temperature's.

I've found that you should "READ" your plugs to see what you have actually going on in the combustion chamber. This is critical in a 2-stoke engine.
Hope this helps
Motobike

 

[buzz sawyer]

Let me add my 2 cents; based on 2-stroke motorcycles:
Spark plug reach, seat type, resistor, have already been discussed so let me say many 2-stroke motorcycle pistons have been ruined by incorrect spark plugs. mainly wrong heat range.
The term heat range, refers to the rate at which the spark plugs can transfer or dissapate the heat generated during combustion from the firing end of it's insulator through the cylinder head and cooling system.

There is more to this than I can put in one paragraph; but caution must be used not to get too far out of the engine's intended heat range of plug. GOOGLE spark plug basics or something and study up on this. We are in an era of changing fuels also, EPA regulated, which can affect temperature's.

I've found that you should "READ" your plugs to see what you have actually going on in the combustion chamber. This is critical in a 2-stoke engine.
Hope this helps
Motobike

I totally agree - +1.

 

[WadePatton]

not that we use the a/m dial anymore, but that's where you'll get the interference.*

i was on a/m broadcast or a/m ham one day and this awful popping sound came on and kept getting stronger. glanced out in the field and saw an old farmall tractor in operation...

non-resistor plugs!

*useful for tracking down electric fence problems too. mof, i tracked down a major problem in my mom's electric service supply line once with a/m.

 

[056kid]

My 250r runs like pure ass with a br9es @ .035, but will make you beg for mercy with a br8es @ .022. .

I had a hack of a time trying to replace the plug that was in it when I bought the trike. It was some autolite with nothing but the numbers 404 that looked to be etched with one of thoes little tools ment for tagging your wrenches...


It all makes me think of the loader operator that used to race motorcross, hes the one that got me into the ATC 250rs, but he will toss a plug with less than 3 hours on it, i will run them till they no longer run. I think he is crazy.

 

[WadePatton]

...to race motorcross, hes the one that got me into the ATC 250rs, but he will toss a plug with less than 3 hours on it, i will run them till they no longer run. I think he is crazy.

i'm with you on that. i replace plugs when they don't fire, or look like they shouldn't be able to fire...

 

[teacherman]

Dolmar did a test with different types of non-approved spark plugs and their effect on coils. According to Dolmar, in the worst case the coil failed within minutes. It's very important to use a resistor plug if that is what the MFG recommends.

I had no idea. I just put a non-resistor plug in my 012, and it seemed a bit less powerful. THANK YOU