Spark plug

[arborworks1]

660 took to running odd on the last take down. Dumped fuel and refilled with fresh. Same result. Pulled plug and to my surprise the electrode had actually broken and was grounding out on idle.

This was my first experience with this. Anyone run across this before?

 

[squisher]

I've never had a plug fail like that. I've had them stop producing spark, but look fine still.

 

[sawinredneck]

It was a Champion wasn't it?

 

[Mr. Sir]

Check your anti-vibration mounts. Sometimes one will break and if you bear down on a big cut the plug can hit the case and break off.

 

[Al Smith]

I've never had a plug go bad on a saw ,never ever .

 

[gf beranek]

Once had the entire electrode ceramic come loose of the plug screw base. The saw run just fine, but the plug would act like a compression release if you pushed down on it while running. Funny.

 

[Underwor]

I can't remember the last time I changed a plug in a saw. When I started with Davey we used to carry a box of them in the truck all the time. Of course we ran the saws at 1/2 pint of oil to the gallon of gas. Could explain a little of the fouling. Also the old breaker point ignition systems were not as hot as the newer electronics I am sure. About all you see now is a loose plug wire or a broken plug. So much for the good old days.

 

[Tree Reb]

I had the ceramic come loose on a couple of Champions, it was a bit hard to figure out what was going on.

I changed to NKG for a while, Bosch if I could get them. Back to Champion now for a couple of years and no problem with them so far.

 

[CurSedVoyce]

My FS 250s will cook plugs every year or so.... But I put way more hours on them in that time than most will on a saw. That and you figure they run almost continuous at 12500-13000 RPM 6-8 hours a day. That my friends is a lot of heat in 100 degree temperatures during the day. On the chain saws.. couple of cracked insulators... probably from rolling down a slope except one, and that was me being pissy getting a boot off

 

[Magnus]

I seen that on NGK, Champion Bosch and no namers, so I doubt it is brand related.
Lower electrode break, fall out, center electrode burn up, cracked isolators...
It happens...

 

[Al Smith]

You have different heat ranges on saw plugs just like automobile plugs .Hot short time run saws like 200T would most likely do better on the hot range and big long run like perhaps a 660 or larger most likely a colder range .

When I ran the antique pulling tractors I ran a set of aviation plugs which cost 18 bucks a pop back then 25-30 years ago .That was only for a 200 foot run .Switched to colder when it ran doing standard tractor stuff .

 

[Burnham]

I've had it happen on a snowmobile...never a saw.

 

[sawinredneck]

I asked because I've had noting but problems with Champion plugs of late. Plug looks good, fires in the air, but wont under compression.
The electrode drops out.
The center of the ceramic drops out.
Someone brings me a mower any more the first thing I do is look at the plug, if it's a Champion it comes out and gets replaced with an NGK, regardless of what I or the customer think is wrong with it. Seems 85% of what I see in mowers and OPE anymore is bad plugs and fuel issues, the rest is just flat carnage!

 

[woodworkingboy]

Speaking about plug aesthetics, since I know it is important to everyone here, the old Bosch were the nicest looking, imo. Plugs now are too generic in appearance, rather boring, sadly.

 

[Bermy]

 

[Magnus]

I asked because I've had noting but problems with Champion plugs of late. Plug looks good, fires in the air, but wont under compression.
The electrode drops out.
The center of the ceramic drops out.
Someone brings me a mower any more the first thing I do is look at the plug, if it's a Champion it comes out and gets replaced with an NGK, regardless of what I or the customer think is wrong with it. Seems 85% of what I see in mowers and OPE anymore is bad plugs and fuel issues, the rest is just flat carnage!

You will find those problems with NGK too.
Bosch was a tad better IMO but still not bullet proof. No plug is.
Just make sure plugs are the same if you switch, changing from factory plug can affect warranty and system.
Did you look why the center fell out or bottom electrode is bent?

 

[woodworkingboy]

If I remove a plug for any reason, I usually wire brush off the carbon. i don't know if it accomplishes anything, but it feels nice.

 

[Al Smith]

It's not a bad idea to replace them every so often .Most people including myself don't though .Say though while on the subject keep in mind there are two types of mounting for want of a better word .Some have a gasket and some use a taper .Best to keep with the same .A gasket might work on a taper but not vica versa .

 

[Magnus]

If you ran it 50hrs a week you would.

 

[Magnus]

You mean the sealing washer under the plug?
Most are the compress type, once compressed the are just washer. Hence the reason to replace when removed.
On the bench I have some aluminum washers I use when needed.

Some saws have cone shape too. These plugs fit in nothing else and vice versa.

 

[arborworks1]

I have been running the 200t for 3 years on the same plug. I bet it sees 25-30 hours a week.

 

[sawinredneck]

I didn't analyze them Magnus, just common failures I've come to expect with Champion, I've yet to have a singe problem with the NGK's in the states, Bosch seem harder to come buy here, they like to sell the multi-electrode version though.

 

[Cobleskill]

The hotter ignition and lower oil amounts seem to give plugs a longer life than they used to years ago. I ran a Husky for over 10 years on the same plug. It started getting hard to start and finally wouldn't. It had built up enough brown deposit to short it out. Once every 10 years isn't bad.

 

[Magnus]

Plug's is not a thing you can save money on not replacing now and then.
It is cheep and not worth the risks to keep them unless it is out of curiosity.
For money making machines I see no reason to not change now and then.

Analyzing the plug is like looking at a printed history of runtime on the saw.
It tells a good story.
There are bad batches of plug's in all brands I think. I had a few boxes here I thrown away as they were not working or defect in both NGK and Champion.
Not from Bosch now that I think of it, just random plugs.

Plug's are good today. I use NGK and Champion mostly. Champion a bit more I guess as it is the preferred brand by HVA.

The importance of using correct plug in a modern saw can not be described well enough.
Using wrong plug have great risks and often high costs as result.

 

[HolmenTree]

When logged with a saw I changed the plug every 2 weeks [80hrs] whether it needed it or not, cheap insurance when your on a piecework rate.
I have always had great success with the Bosch plugs made in Germany, but not the ones from Brazil or India so much.