cmetalbend
ArboristSite Operative
With all the mods we discuss on a daily basis, does anybody but me just check the plug after an adjustment. I mean it truly tells the story, IMO better than the sound (which I use to get close).
opcorn:
opcorn:
Does anybody just check the plug?
- Thread starter cmetalbend
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Cadenhill
ArboristSite Member
You are right. I checked the plugs on 2 saws yesterday. Its a good indicator of being to lean, most people know when their saw is to rich. I make sure that I am not leaned out to much. Never blown one up yet in a lot of years of cutting, and I like to hear my saws scream.
cmetalbend
ArboristSite Operative
I agree Screeeeeeeeeeeeeeeeeeeam, I just tested one a few minutes ago, One thing I might mention, I believe to get a good reading, Run it at wot in a cut and shut it off just as the cut is completed, don't let it idle. I think the idle (if set alittle rich) can scue the result.
Cadenhill
ArboristSite Member
Good Point!!!!!!
timberwolf
Addicted to ArboristSite
Need to look beyond just the tip of the ground strap. Found too that oil and fuel will play with appearance, running alcohol heavy with castor oil turns reading plug on it's ear if comparing against a gas plug run at 40 or 50 to 1.
I've seen plug runs on 100LL and they seem to be a lot lighter than I'm used to.
cmetalbend
ArboristSite Operative
ah ya, I'm gonna stay away from those odd fuel/oil mixes.
John D
Addicted to ArboristSite
All my saws are stock,but I let one of my guys "adjust" the high speed mixture when i was busy.It was a very hot day,and the tree was a huge oak,about 30" at the base.The saw my old trusty homelite super XL. It stuck the piston,seized it right up,when i pulled the plug it was dark golden brown.I still dont know why it stuck other than the heat,as oil mix was right on. Plug seemed fine. I was expecting a white plug tip.I do check my plugs,but only after making a carb adjustment or change. I have quite abit of experience with small engines,as most of you know you can feel how rich or lean a saw is after youve run it long enough.By the how cold blooded it is,how crisp the throttle response,how clean it revs,and the smoke, you can usually tell how its running.
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ned coed
ArboristSite Member
the plug was dark golden brown.....hummm.? what colour was the top of the piston and check on the colour of the combustion chamber that might give you a better idea what was happening just before lockup.
or just could be that the rings snapped and locked it up so it might not have been a carb adjustment fault??
or just could be that the rings snapped and locked it up so it might not have been a carb adjustment fault??
lovetheoutdoors
Addicted to ArboristSite
yep if im gonna tune on a saw i deffinatly check the plug to see how lean or rich it is...but if the saw is running well and no adjustments are being made i dont check it that much :jawdrop: .
RiverRat2
Serio Tree Freak
Yeppp!!!!!
some good post here,,,, cannot just depend on the plug alone!!!! especially
if yer spinning it harder(modified moto's) and using exotic fuels must look @ the big picture,,,
LOLOL!!!!!! :agree2:
some good post here,,,, cannot just depend on the plug alone!!!! especially
if yer spinning it harder(modified moto's) and using exotic fuels must look @ the big picture,,,
LOLOL!!!!!! :agree2:
"plug chops" can be very deceiving when you aren't using a new one!
John D
Addicted to ArboristSite
top of piston was brown as well,rings were worn,but not broken.The port edges were smooth.I freed it up,ran a small hone down it,and reassembled it after lightly sanding with piston skirt with emery paper.I havent been able to find piston/rings for it locally,my dealer says parts arent available.It runs,but it doesnt make full power anymore,as compression is barely 100psi,but its a good backup saw. I ran that saw hard,I liked that saw better than the old 041 AV Stihl,it had more power,started better and faster,and was lighter.
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I was just playing with the carb settings yesterday. I was trying to use the rest of the tank of mix to get it ready to be stored for the winter (Some just empty it, I like to play a little). It was quite educational to slowly tweak the settings and see the difference it made in cutting. I learned a lot from it. Now I think I'll go check on that plug....
Tzed250
Addicted to ArboristSite
Plug reading is not accurate unless you are very intimate with the engine and are experienced at seeing what changes have what effects on plug appearance. The ring on the insulator is what you are after and the only way to see it clearly is with an illuminated coddington magnifier.
I trust the exhaust note much more than a plug chop, but if you tune the saw by timed cuts, then do a plug chop and take note of what the plug looks like you will have a backup tuning method for that saw with that fuel and oil mix.
I trust the exhaust note much more than a plug chop, but if you tune the saw by timed cuts, then do a plug chop and take note of what the plug looks like you will have a backup tuning method for that saw with that fuel and oil mix.
cmetalbend
ArboristSite Operative
Those things are neat, we used them When I was running alot of nitrous oxide in my car . Except we were looking for tiny particals of Aluminum, well I guess it really isn't that different.Plug reading is not accurate unless you are very intimate with the engine and are experienced at seeing what changes have what effects on plug appearance. The ring on the insulator is what you are after and the only way to see it clearly is with an illuminated coddington magnifier.
I trust the exhaust note much more than a plug chop, but if you tune the saw by timed cuts, then do a plug chop and take note of what the plug looks like you will have a backup tuning method for that saw with that fuel and oil mix.
opcorn:yukiginger
ArboristSite Member
Plug checking
I am no small engine guy, that's for sure. Could you guys elaborate a little on exactly what you are checking or seeing when you examine the plug and what you mean by telling how you are tuned or running by looking at the plug?
MarkG
I am no small engine guy, that's for sure. Could you guys elaborate a little on exactly what you are checking or seeing when you examine the plug and what you mean by telling how you are tuned or running by looking at the plug?
MarkG
Octane
ArboristSite Operative
Looking at the spark plug electrode can give you a good idea or whether or mixture is too rich or too lean.
Its not the end-all, be-all; but in addition to how the exhaust note sounds, the idle rpm and just the overall running quality of the engine; reading the plugs is a good indicator of how close your mixture screw settings are.
Its not the end-all, be-all; but in addition to how the exhaust note sounds, the idle rpm and just the overall running quality of the engine; reading the plugs is a good indicator of how close your mixture screw settings are.
Octane
ArboristSite Operative
I look at the electrode. You want it to be a chocolate brown to tan color. If its white you are too lean. If its darker than a chocolate brown or has carbon built up on it, you are too rich.
wkpoor
Addicted to ArboristSite
Here is the plug out of my 395XP after many hours of use this summer. This typical of what I see. However one that I pulled at Eric's GTG from My 681 had some deposits on it. I think that saw might be running rich. I richened up my 395 last time I ran it as it was turning 13.5K and that is a bit quick for a stock one. All my saws run on AvGas only.
